Fact-checked by Grok 2 weeks ago

Cough

A cough is a sudden, often involuntary, expulsion of air from the lungs through the mouth, serving as a protective reflex mechanism to clear the airways of irritants, excess secretions, mucus, and foreign particles.^[1]^[2] This reflex is triggered by mechanical or chemical stimuli in the respiratory tract, which activate sensory nerves—primarily via the vagus nerve—sending signals to the brainstem to coordinate muscle contractions in the chest, diaphragm, and abdomen, building intrathoracic pressure exceeding 300 mm Hg before a rapid release of air at high speeds, up to 100 miles per hour.^[1] Coughing is a normal and essential function for maintaining airway patency and mucociliary clearance, but persistent or severe episodes can lead to complications such as fatigue, dizziness, rib fractures, or disrupted sleep.^[2]^[1] Coughs are classified by duration into acute (lasting less than 3 weeks), subacute (3 to 8 weeks), and chronic (more than 8 weeks in adults or 4 weeks in children), with the latter often signaling an underlying medical condition rather than a transient response.^[1]^[3] Acute coughs typically arise from self-limiting infections or irritants and resolve without intervention, while chronic coughs may persist due to multifactorial causes and require diagnostic evaluation.^[1] Accompanying symptoms can include production of sputum (wet cough) or absence of it (dry cough), postnasal drip, wheezing, hoarseness, sore throat, or, in rare cases, hemoptysis (coughing up blood).^[3] Common causes of cough vary by type and include viral upper respiratory infections (such as the common cold or acute bronchitis, accounting for about 90% of acute cases), postinfectious airway inflammation, asthma exacerbations, gastroesophageal reflux disease (GERD, implicated in up to 40% of chronic cases), and upper airway cough syndrome from postnasal drip.^[1]^[3] Other etiologies encompass chronic obstructive pulmonary disease (COPD), smoking-related bronchitis, pertussis (whooping cough), medications like ACE inhibitors, and less frequently, malignancies or infections such as tuberculosis.^[1]^[3] Epidemiologically, cough is the most frequent symptom prompting medical consultations, leading to up to 30 million outpatient visits annually in the United States, with a prevalence ranging from 5% to 40% influenced by factors like smoking and environmental exposures.^[1] Medical attention is advised for coughs lasting beyond 3 weeks, those producing bloody or discolored mucus, or accompanied by fever, weight loss, shortness of breath, or chest pain, as these may indicate serious conditions requiring prompt assessment.^[2]^[3]

Presentation

Symptoms and Characteristics

A cough is defined as a sudden, often involuntary, forceful expulsion of air from the lungs through the mouth, serving as a protective mechanism to clear the airways of irritants, mucus, or foreign particles.^[1] This reflex action originates from the stimulation of sensory receptors in the respiratory tract, triggering a coordinated muscular response involving the diaphragm, abdominal muscles, and vocal cords to generate high-velocity airflow.^[4] Coughs are broadly classified by their productivity: a dry or non-productive cough produces no sputum and often feels irritating without relieving congestion, whereas a wet or productive cough expels mucus or phlegm, aiding in clearing secretions from the lower airways.^[5]^[2] Coughs vary in timing and severity, which can provide clues to their nature. Nocturnal coughs predominate at night, often worsening when lying down due to increased mucus drainage or irritation, while postprandial coughs occur after meals, potentially linked to swallowing or reflux-related sensations.^[6] Severity ranges from mild, occasional episodes that minimally disrupt daily activities to paroxysmal coughs characterized by intense, uncontrollable bursts that may cause exhaustion or temporary breathlessness.^[1] These patterns can influence patient comfort and sleep, with paroxysmal forms sometimes leading to repeated hacking spells throughout the day or night.^[7] Coughs are further categorized by duration to guide clinical evaluation. Acute coughs last less than three weeks and are typically self-limiting, subacute coughs persist for three to eight weeks, often following an initial acute phase, and chronic coughs endure beyond eight weeks, requiring more thorough assessment.^[8]^[9] These classifications help distinguish transient responses from ongoing issues without implying specific origins.^[10] Patients often experience associated symptoms alongside the cough itself, such as a sore throat from repeated irritation, chest pain or tightness due to muscular strain, and wheezing indicating narrowed airways.^[11]^[4] Sensorily, coughs are commonly preceded by a tickling or itching sensation in the throat, accompanied by an intense urge to cough that builds until expulsion provides temporary relief.^[12] This urge-to-cough sensation, distinct from pain, can feel like an irritating scratch or paraesthesia localized to the larynx or upper airways.^[13]

Complications

Coughing, particularly when prolonged or forceful, can lead to a variety of complications arising from the mechanical forces generated during the act. These include musculoskeletal injuries such as rib fractures, which occur due to the repetitive stress on the thoracic cage, especially in individuals with osteoporosis or during severe coughing episodes.^[14]^[3] Muscle strains in the chest wall, abdomen, or diaphragm are also common, while hernias—such as inguinal, hiatal, or abdominal wall types—may develop from increased intra-abdominal pressure.^[15]^[14] Cardiovascular effects stem from transient elevations in intrathoracic pressure, which can cause cough syncope—a temporary loss of consciousness due to reduced cerebral blood flow—or arrhythmias like bradyarrhythmias.^[15]^[14] Subconjunctival hemorrhage, presenting as painless red spots in the eyes from ruptured vessels, is another frequent minor complication.^[14]^[15] Respiratory complications often involve worsening of pre-existing conditions, such as asthma exacerbations triggered by the irritative effects of coughing, or more severe issues like pneumothorax in cases of underlying lung fragility.^[4]^[14] Gastrointestinal disturbances include vomiting induced by intense coughing bouts and aggravation of gastroesophageal reflux disease (GERD) due to repeated pressure on the lower esophageal sphincter.^[3]^[4]^[14] Among rarer events, urinary incontinence may result from weakened pelvic floor muscles strained by coughing, particularly in older adults or those with prior incontinence.^[3]^[14] Over the long term, persistent coughing contributes to fatigue and sleep disruption, impairing overall quality of life and leading to psychosocial burdens like anxiety over health.^[3]^[14] Chronic cough lasting more than eight weeks heightens the risk for these complications.^[14]

Pathophysiology

Cough Reflex

The cough reflex is a vital protective mechanism that expels irritants, mucus, and foreign particles from the respiratory tract through coordinated neural and muscular activity.^[16] It involves a reflex arc comprising sensory detection, central processing, and motor response, triggered by stimulation of specialized receptors in the airways.^[17] This reflex ensures airway clearance and prevents aspiration, thereby reducing the risk of complications such as pneumonia.^[18] The reflex proceeds in three distinct phases. The inspiratory phase begins with a deep inhalation, where the glottis opens and the diaphragm along with external intercostal muscles contract to draw air into the lungs, typically reaching about 50% of vital capacity.^[17] This is followed by the compressive phase, during which the epiglottis and vocal cords close, and abdominal, intercostal, and diaphragm muscles contract to build intrathoracic pressure up to 300 mm Hg.^[18] Finally, the expiratory phase involves relaxation of the glottis, allowing forceful expulsion of air at velocities up to 100 km/h (28 m/s), which dislodges and ejects material from the airways.^[18]^[19] Afferent signals initiating the reflex arise from cough receptors, including rapidly adapting receptors, slowly adapting stretch receptors, and C-fibers, located primarily in the pharynx, larynx, trachea, and bronchi.^[17] These receptors detect mechanical irritation, chemical stimuli, or inflammation and transmit impulses via branches of the vagus nerve, such as the superior laryngeal and recurrent laryngeal nerves, to the brainstem.^[18] Central integration occurs in the medulla oblongata, where the nucleus tractus solitarius receives and processes afferent inputs, coordinating with the medullary cough center and adjacent nuclei like the nucleus retroambigualis and nucleus ambiguus.^[17] This processing determines whether the stimulus exceeds the cough threshold, integrating sensory data to generate an appropriate response pattern.^[16] Efferent output from the central cough center travels via the vagus, phrenic, and spinal motor nerves to activate key muscles, including the diaphragm for inspiration, laryngeal muscles for glottis control, and abdominal and internal intercostal muscles for expiration.^[18] This coordinated activation ensures the sequential phases of the reflex unfold efficiently. The threshold and sensitivity of the cough reflex vary; in normal states, it responds to significant irritants, but hypersensitivity can occur in conditions like inflammation, making the reflex more easily triggered, while hyposensitivity impairs clearance.^[18] Women generally exhibit higher sensitivity compared to men.^[18] Overall, the cough reflex plays an essential protective role by clearing excessive secretions, foreign bodies, and pathogens from the airways, thereby maintaining respiratory homeostasis and preventing atelectasis or infection.^[20]

Neural and Mechanical Mechanisms

The neural mechanisms underlying cough involve both peripheral and central sensitization processes that amplify the cough reflex in response to airway irritation. Peripheral sensitization occurs primarily through the activation of transient receptor potential vanilloid 1 (TRPV1) receptors expressed on C-fiber nociceptors in the airway mucosa and vagal afferent nerves. These receptors detect chemical irritants, such as capsaicin or acid, leading to heightened sensitivity and enhanced cough responses by depolarizing sensory neurons and releasing neuropeptides like substance P.^[21] Similarly, adenosine triphosphate (ATP), released from damaged epithelial cells during inflammation, sensitizes airway nerves via P2X3 receptors, which are purinergic ion channels on vagal afferents that facilitate rapid calcium influx and neuronal firing, contributing to tussive hypersensitivity.^[22] These peripheral changes lower the threshold for cough initiation, transforming innocuous stimuli into potent triggers. Central sensitization further modulates cough by altering processing in the brainstem and higher cortical regions, culminating in cough hypersensitivity syndrome (CHS), a condition characterized by exaggerated neural responsivity to diverse stimuli affecting the airways, larynx, and esophagus. In the brainstem, particularly the nucleus tractus solitarius and parabrachial nucleus, incoming vagal signals undergo integration and amplification through synaptic plasticity, including long-term potentiation, which sustains heightened excitability.^[23] Cortical involvement, via areas like the insula and anterior cingulate cortex, adds voluntary control and emotional modulation, where reduced inhibitory activity can perpetuate chronic coughing by failing to dampen reflexive outputs.^[24] This central dysregulation in CHS often persists beyond initial insults, reflecting a shift from protective reflex to maladaptive hypersensitivity. Mechanically, cough generates explosive forces to clear airways, with expiratory airflow velocities reaching up to 60 miles per hour (approximately 27 meters per second) during the expulsion phase, driven by rapid glottal opening and subglottic pressure buildup. These high velocities produce substantial shear stresses on the airway walls, estimated at up to 14 pascals in simulations of peak flows, which dislodge mucus and pathogens by creating turbulent flow and direct mechanical abrasion.^[25] Such biomechanics underscore cough's efficacy as a clearance mechanism but also risk airway trauma in hypersensitive states. Recent research from 2024 and 2025 highlights neuroinflammation and vagal neuropathy as key drivers in refractory chronic cough, where proinflammatory cytokines like IL-1β and TNF-α infiltrate vagal ganglia, promoting demyelination and ectopic firing in afferent nerves. In post-infectious cases, particularly following SARS-CoV-2, viral neurotropism—direct invasion of neural tissues by the virus—exacerbates this through persistent microglial activation and disrupted vagal signaling, leading to prolonged hypersensitivity.^[26] Gender differences influence these pathways, with chronic cough prevalence approximately twice as high in females, attributed to estrogen's enhancement of TRPV1 expression and synaptic plasticity in vagal and cortical circuits during puberty and beyond.^[27]^[28] Inhibitory mechanisms counteract excessive coughing via endogenous opioids and GABAergic neurotransmission in the brainstem. Endogenous opioids, such as enkephalins, bind mu and kappa receptors on cough-related neurons in the nucleus tractus solitarius, hyperpolarizing cells to suppress reflex arcs and reduce central drive.^[29] GABA, acting through GABAB receptors on presynaptic terminals, inhibits neurotransmitter release from excitatory afferents, providing tonic suppression that diminishes in CHS due to receptor downregulation.^[30] These pathways maintain balance, preventing overactivation while preserving defensive coughing.

Causes

Infectious Causes

Infectious causes of cough primarily involve microbial pathogens that invade the respiratory tract, triggering irritation of the cough reflex through inflammation and mucus production.^[31] These infections range from self-limiting upper respiratory illnesses to severe lower respiratory tract diseases, with viruses accounting for the majority of acute cases.^[32] Viral infections are the most common infectious etiology of cough, often presenting as acute respiratory illnesses. The common cold, primarily caused by rhinoviruses, typically features a dry or productive cough lasting 1-3 weeks, accompanied by nasal congestion and sore throat. Influenza viruses induce a more severe cough, frequently with fever, myalgias, and fatigue, which can persist for several weeks in uncomplicated cases. Respiratory syncytial virus (RSV) is a leading cause of cough in infants and young children, resulting in bronchiolitis with wheezing and respiratory distress, though it can affect adults as well. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for COVID-19, commonly manifests with a dry cough during acute infection, and post-acute sequelae include chronic cough in over 30% of cases, as reported in cohort studies from 2023-2025.^[33]^[34] Bacterial infections contribute to cough in both acute and chronic settings, often following viral predisposition or occurring independently. Pertussis, caused by Bordetella pertussis, produces characteristic paroxysmal coughing fits ending in inspiratory whoops, particularly severe in unvaccinated individuals. Pneumonia due to Streptococcus pneumoniae features productive cough with purulent sputum, chest pain, and fever, representing a major cause of community-acquired lower respiratory infection. Tuberculosis, induced by Mycobacterium tuberculosis, leads to chronic cough lasting over three weeks, often with hemoptysis in advanced pulmonary disease. Fungal infections are less common but significant in immunocompromised hosts, where they can cause invasive disease with prominent cough. Aspergillosis, resulting from Aspergillus species inhalation, manifests as chronic cough with hemoptysis in conditions like neutropenia or HIV/AIDS. Parasitic infections rarely cause cough but can involve the lungs through larval migration. Ascariasis, due to Ascaris lumbricoides, may lead to cough during the pulmonary phase of migration, typically in endemic regions with poor sanitation. Most respiratory infections spread via respiratory droplets from coughing or sneezing, with many exhibiting seasonal peaks in winter due to indoor crowding and lower humidity facilitating viral survival. Post-infectious cough can persist for up to 8 weeks after viral resolution, attributed to heightened airway inflammation and hypersensitivity.

Non-Infectious Causes

Non-infectious causes of cough encompass a range of intrinsic respiratory, systemic, and neurological conditions that trigger the cough reflex without involvement of microbial pathogens. These etiologies often stem from chronic inflammation, mechanical irritation, or structural abnormalities in the airways or related systems, leading to persistent or recurrent coughing that can significantly impact quality of life. Common mechanisms include heightened airway sensitivity or direct stimulation of cough receptors, distinguishing them from acute infectious processes. Reactive airway diseases represent a primary category of non-infectious cough triggers. In cough-variant asthma, patients present with a dry, non-productive cough as the predominant symptom, often worsening at night or with exercise, due to eosinophilic inflammation and bronchial hyperresponsiveness without typical wheezing. Chronic obstructive pulmonary disease (COPD) exacerbations can also manifest as cough, particularly in smokers or those with emphysema, where mucus hypersecretion and airflow limitation irritate the airways, though this is distinct from infectious flares. Gastroesophageal reflux disease (GERD) frequently causes cough through microaspiration of gastric acid into the larynx and upper airways, leading to chemical irritation and reflex coughing, especially in supine positions. This is supported by studies showing improvement with proton pump inhibitors in GERD patients with chronic cough, highlighting the role of laryngopharyngeal reflux. Cardiac conditions, such as congestive heart failure, provoke cough via pulmonary edema that accumulates fluid in the alveoli, stimulating juxtacapillary receptors and often presenting nocturnally as orthopnea-associated coughing. Allergic mechanisms contribute to cough through postnasal drip from allergic rhinitis, where inflammatory mediators cause nasal congestion and mucus drainage that irritates the pharynx and triggers the cough reflex. This is particularly evident in seasonal allergies, with histamine release exacerbating upper airway sensitivity. Neoplastic causes include lung cancer, where tumors directly compress or invade bronchi, eliciting persistent cough often accompanied by hemoptysis, and mediastinal tumors that impinge on the vagus nerve or major airways, leading to irritative symptoms. Habit cough, also known as psychogenic cough, typically occurs in children following a resolved upper respiratory illness and manifests as a repetitive, tic-like barking sound that resolves with distraction but persists during wakefulness. It is linked to psychological factors rather than organic disease, with behavioral therapies proving effective. Neurogenic cough arises from vagus nerve irritation, such as post-surgical complications or tumors affecting the recurrent laryngeal nerve, resulting in chronic, refractory coughing due to aberrant neural signaling. Neural hypersensitivity serves as a common pathway in many of these conditions, amplifying cough responses to otherwise innocuous stimuli.

Environmental and Iatrogenic Causes

Environmental causes of cough encompass exposures to airborne irritants that provoke airway inflammation and reflexive expulsion of foreign material. Air pollution, particularly from particulate matter (PM), smoke, and ozone, directly irritates the respiratory epithelium, leading to acute and chronic cough as a protective response. Fine particulate matter (PM2.5) and ground-level ozone penetrate deep into the lungs, causing oxidative stress and mucus hypersecretion that manifest as persistent coughing, especially in urban environments with high pollution levels. Historical episodes of severe urban smog, such as those involving heavy coal smoke and industrial emissions, have been linked to sharp rises in respiratory irritation and cough prevalence, exacerbating morbidity in vulnerable populations.^[35]^[36]^[37] Occupational exposures represent a significant subset of environmental triggers, where prolonged contact with dust, fumes, and chemicals induces irritant-mediated cough and related conditions. Workers in industries like mining, construction, and manufacturing face elevated risks from inhaling silica dust, metal particles, or volatile organic compounds, which inflame the bronchi and provoke chronic cough as an early symptom. For instance, exposure to cement dust has been associated with increased cough and phlegm production due to mechanical irritation and chemical reactivity in the airways. Irritant-induced occupational asthma often begins with non-productive cough following high-level exposures, progressing to wheezing and dyspnea if unaddressed.^[38]^[39]^[40] Tobacco smoking stands out as a pervasive environmental irritant, driving the development of chronic bronchitis through repeated exposure to tar, nicotine, and combustion byproducts that damage ciliary function and stimulate goblet cell hyperplasia. This results in a productive cough that persists for at least three months annually over two consecutive years, serving as a hallmark of smoker's cough. The irritants in cigarette smoke not only initiate but also perpetuate airway remodeling, making cough a daily occurrence for many long-term smokers.^[41]^[42] Climatic factors, including cold air and seasonal allergens, can trigger cough by altering airway temperature, humidity, or allergen load. Inhalation of cold, dry air during winter months cools and dehydrates the respiratory mucosa, heightening sensitivity to irritants and inducing reflex cough, particularly in individuals with underlying hyperreactivity. Seasonal shifts amplify this through pollen or mold spores, which deposit in the airways and provoke allergic cough during peak bloom periods, often worsening in polluted or changing climates.^[43]^[44] Foreign body aspiration, often from choking on small objects like food or toys, abruptly initiates intense cough as the body's mechanism to clear the obstruction from the trachea or bronchi. This event is predominantly reported in children aged 1 to 3 years, where exploratory behaviors increase aspiration risks, with cough being the most common initial symptom in over 80% of cases. Delayed diagnosis can lead to protracted cough mimicking chronic respiratory issues.^[45]^[46] Iatrogenic causes primarily involve medications that inadvertently stimulate cough pathways. Angiotensin-converting enzyme (ACE) inhibitors, such as lisinopril, commonly prescribed for hypertension and heart failure, elevate bradykinin levels by inhibiting its degradation, resulting in a dry, non-productive cough affecting 5-20% of users, typically emerging within weeks to months of initiation. This side effect arises from bradykinin-induced airway hypersensitivity and is more prevalent in women and nonsmokers. Switching to alternative agents like angiotensin receptor blockers often resolves the cough.^[47]^[48]

Diagnostic Approach

History and Examination

The initial evaluation of cough begins with a detailed medical history to characterize the symptom and identify potential etiologies. Key elements include the onset (sudden or gradual), duration (acute less than 3 weeks, subacute 3 to 8 weeks, or chronic more than 8 weeks in adults), and associated features such as triggers like lying down or bending over, which may suggest gastroesophageal reflux disease (GERD).^[49]^[50] Inquiries should cover sputum characteristics, including color (e.g., purulent suggesting infection) and volume, as well as smoking history, occupational or environmental exposures (e.g., dust, chemicals, or travel to endemic areas), and medication use such as angiotensin-converting enzyme (ACE) inhibitors, which are common iatrogenic causes.^[51]^[49] Red flags in the history warrant urgent evaluation to rule out serious conditions. These include hemoptysis, unintentional weight loss, recurrent pneumonia, night sweats, or symptoms suggestive of malignancy or tuberculosis (TB), such as prolonged cough in smokers or those with immunosuppression.^[49]^[51] Other concerning features encompass progressive dyspnea, chest pain, or hoarseness, which may indicate airway obstruction or laryngeal involvement.^[50] Physical examination complements the history by focusing on non-invasive assessments. Vital signs should be checked for tachycardia, fever, or hypoxia indicating systemic involvement. Lung auscultation may reveal wheezes (suggesting asthma or bronchospasm), crackles (indicating interstitial disease or infection), or diminished breath sounds (possible effusion or consolidation).^[51]^[49] Examination of the ear, nose, and throat (ENT) structures is essential to identify postnasal drip, nasal polyps, or sinus tenderness associated with upper airway cough syndrome. Abdominal palpation can detect epigastric tenderness or hepatomegaly relevant to GERD or other gastrointestinal contributors.^[50]^[51] Validated questionnaires aid in quantifying cough severity and its impact on daily life. The Leicester Cough Questionnaire (LCQ), a 19-item tool assessing physical, psychological, and social domains over the past 2 weeks or 10 days, is widely used to measure cough-related quality of life, with scores ranging from 3 to 21 (lower scores indicating greater impairment).^[51]^[49] Age-specific considerations are crucial, as cough patterns differ between pediatric and adult patients. In children, chronic cough is defined as lasting more than 4 weeks, and history should probe for barking or brassy quality suggestive of croup or tracheomalacia, paroxysmal episodes resembling pertussis, or wet productive cough indicating protracted bacterial bronchitis; red flags include failure to thrive or digital clubbing.^[52] Physical exam in pediatrics emphasizes growth parameters and may reveal chest wall deformities. In adults, cough often relates to hypersensitivity syndromes, with higher prevalence in middle-aged women, and history focuses on chronic irritant exposures.^[51]^[52]

Investigations and Tests

Investigations and tests for cough focus on objective assessments to identify underlying causes, guided by clinical history to prioritize appropriate modalities.^[50] Recent guidelines, including the 2025 WAO-ARIA consensus, emphasize a treatable traits approach for refractory cases, incorporating assessments for cough hypersensitivity alongside traditional tests.^[53] Chest radiography serves as an initial imaging tool, recommended for evaluating persistent cough to detect structural abnormalities such as pneumonia, lung tumors, or aspirated foreign bodies, with guidelines emphasizing its role in excluding serious pathology before further testing.^[9]^[54] Pulmonary function tests, particularly spirometry, are essential for assessing airflow obstruction in suspected cases of asthma or chronic obstructive pulmonary disease (COPD), measuring forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) to quantify obstruction with a FEV1/FVC ratio below 0.7 indicating potential disease.^[50]^[55] Sputum analysis complements this by enabling microbiological culture to identify infectious agents like bacteria or mycobacteria in productive cough, while cytological examination detects malignant cells suggestive of lung cancer, particularly in smokers or those with risk factors.^[54]^[56] For cough linked to gastroesophageal reflux disease (GERD), ambulatory esophageal pH monitoring quantifies acid exposure over 24-48 hours to confirm reflux episodes correlating with symptoms, often combined with esophageal manometry to evaluate motility disorders that may contribute to reflux-induced cough.^[57]^[58] Bronchoscopy provides direct visualization of the airways, allowing biopsy or removal of foreign bodies, tumors, or inflammatory lesions, and is indicated when imaging suggests endobronchial pathology or cough persists despite initial evaluations.^[54]^[59] Allergy testing, such as skin prick tests, identifies IgE-mediated sensitization to aeroallergens in cases of upper airway cough syndrome due to allergic rhinitis, where positive wheal responses greater than 3 mm indicate relevant triggers like pollen or dust mites.^[60]^[61] Emerging protocols for cough hypersensitivity syndrome, a common feature in refractory chronic cough, utilize capsaicin inhalation challenges to measure tussive response thresholds, with 2024 studies standardizing dose-response endpoints to differentiate hypersensitivity from healthy controls, aiding in targeted neuromodulator therapy selection.^[62]^[63]

Classification of Cough

Coughs are classified primarily by duration, productivity, and etiology to facilitate differential diagnosis and management strategies. This taxonomy helps clinicians distinguish between self-resolving episodes and those requiring further evaluation, as the underlying mechanisms and implications vary significantly across categories. Recent 2025 reviews highlight the integration of hypersensitivity assessments in classifications for unexplained cases.^[1]^[64]

By Duration

Cough duration is a foundational classification criterion, dividing cases into acute, subacute, and chronic based on persistence. Acute cough lasts less than 3 weeks and is often associated with viral upper respiratory infections, resolving without specific intervention in most cases.^[1]^[65] Subacute cough persists for 3 to 8 weeks, frequently representing a post-infectious phase following resolution of the initial acute illness, such as after viral bronchitis.^[1]^[8] Chronic cough endures beyond 8 weeks in adults or 4 weeks in children and is typically multifactorial, involving persistent inflammation, neural sensitization, or underlying chronic conditions like asthma or gastroesophageal reflux disease (GERD).^[8]^[65]

By Productivity

Productivity refers to whether the cough produces sputum or mucus, influencing its physiological role and clinical assessment. A productive cough involves expectoration of secretions, which aids in clearing the airways of pathogens, irritants, or excess mucus, commonly seen in infections or chronic obstructive pulmonary disease (COPD).^[66]^[65] In contrast, a non-productive or dry cough lacks noticeable sputum and often feels irritating or tickling, stemming from heightened airway sensitivity without significant secretion buildup, as in early viral infections or allergic responses.^[66]^[65] This distinction guides symptomatic relief, emphasizing suppression for dry coughs while supporting clearance for productive ones.^[65]

By Etiology

Etiological classification localizes the cough to upper airway, lower airway, or non-respiratory origins, reflecting the anatomical site of irritation or dysfunction. Upper airway causes, collectively termed upper airway cough syndrome (UACS), include postnasal drip from rhinitis or sinusitis, where mucus drainage triggers laryngeal irritation.^[1]^[65] Lower airway etiologies involve bronchial or parenchymal issues, such as asthma or chronic bronchitis, where inflammation or bronchoconstriction provokes cough through direct airway stimulation.^[1]^[67] Non-respiratory causes extend beyond the lungs, encompassing GERD, where acid reflux sensitizes esophageal and vagal nerves, or cardiac conditions like congestive heart failure, leading to pulmonary congestion and cough.^[1]^[67]

Special Classifications

Refractory chronic cough, often unexplained after standard evaluations, is increasingly recognized as cough hypersensitivity syndrome (CHS), characterized by exaggerated neural responses to innocuous stimuli like odors or temperature changes, independent of identifiable structural disease.^[68]^[69] This condition highlights a sensory neuropathy in the cough reflex arc, affecting up to 40% of chronic cough patients.^[69]

Prognostic Classifications

Prognostically, coughs are differentiated as self-limiting or progressive to predict outcomes and urgency. Self-limiting coughs, typical of acute viral etiologies, resolve spontaneously within weeks without long-term sequelae.^[1]^[70] Progressive coughs, often chronic and linked to conditions like idiopathic pulmonary fibrosis or untreated asthma, indicate worsening underlying disease and poorer prognosis if unaddressed.^[71]^[70]

Treatment

Acute Cough Management

Acute cough, defined as lasting less than three weeks and frequently caused by viral upper respiratory infections, is generally self-limiting and managed through supportive measures aimed at symptom relief rather than curing the underlying cause.^[1] Maintaining hydration by drinking plenty of fluids helps thin mucus secretions, promoting easier clearance from the airways, while using a humidifier to add moisture to the air can soothe irritated tissues and loosen phlegm for more effective coughing. Cool-mist humidifiers are preferred, especially in households with children, as they reduce the risk of burns and should be maintained at 40-50% humidity with daily cleaning to prevent bacterial growth.^[72] These non-pharmacologic approaches are foundational for managing productive coughs associated with acute conditions. Over-the-counter options include expectorants like guaifenesin for productive coughs, which works by reducing mucus viscosity to enhance expectoration and has shown benefits in decreasing cough frequency and intensity in upper respiratory tract infections. For soothing irritation, particularly in children, honey has demonstrated efficacy; a 2023 systematic review of randomized controlled trials found low-quality evidence that it reduces cough frequency and severity more effectively than placebo or standard cough medications, while also improving sleep, though high-quality trials are needed for confirmation. Antitussives such as dextromethorphan are suitable for suppressing dry, non-productive coughs by blunting the cough reflex, with typical dosing of 10-20 mg every 4-6 hours in adults, but they are not recommended for children under 6 years due to limited efficacy and safety concerns.^[1]^[73]^[1] Avoiding environmental irritants is crucial, including immediate smoking cessation if applicable, as tobacco smoke exacerbates airway inflammation and prolongs symptoms, and removing exposure to allergens or pollutants can prevent worsening of the cough. Antibiotics are not routinely indicated for acute cough, which is predominantly viral, but should be considered only upon confirmation of a bacterial etiology, such as in suspected pertussis cases where macrolides like azithromycin are preferred to reduce transmission and severity if initiated early.^[74]^[75]^[75] Medical evaluation is warranted if the cough persists beyond three weeks, or if accompanied by red flags such as fever above 100.4°F, shortness of breath or dyspnea, bloody mucus, or wheezing, as these may signal complications like pneumonia requiring prompt intervention.^[76]

Chronic Cough Management

Management of chronic cough begins with identifying and treating underlying etiologies, as this forms the cornerstone of a stepwise approach guided by cough classification. For cough-variant asthma, inhaled corticosteroids are recommended to reduce airway inflammation and suppress symptoms, often combined with bronchodilators for optimal control.^[49] In cases linked to gastroesophageal reflux disease (GERD), proton pump inhibitors (PPIs) such as omeprazole are trialed for 2-3 months to alleviate acid-related irritation of the esophagus and airways.^[77] Postnasal drip syndrome, commonly due to rhinitis, is addressed through lifestyle measures including saline nasal irrigation, avoidance of irritants, and intranasal corticosteroids to decrease mucus production and drainage.^[49] When underlying causes are addressed but cough persists, behavioral interventions like speech-language therapy are employed to suppress the cough reflex and reduce hypersensitivity. This therapy involves techniques such as the "sniff-twitch-swallow" method, where patients learn to sniff gently, twitch the soft palate, and swallow to interrupt the urge-to-cough cycle, alongside relaxed breathing exercises to desensitize laryngeal triggers.^[78] Evidence supports its efficacy in refractory cases, with improvements in cough frequency and quality of life observed in clinical trials.^[79] For neuropathic or refractory chronic cough characterized by central sensitization, low-dose neuromodulators are used off-label to modulate aberrant neural pathways. Amitriptyline at 10-25 mg daily or gabapentin at 300-900 mg daily can reduce cough severity by targeting vagal nerve hypersensitivity, with systematic reviews confirming benefits in select patients unresponsive to standard therapies.^[80] These agents are titrated slowly to minimize side effects like drowsiness.^[81] Airway clearance strategies are integrated for productive chronic cough, particularly in those with mucus hypersecretion. Physiotherapy techniques, including postural drainage and breathing exercises, facilitate expectoration, while mucolytics such as N-acetylcysteine (600 mg orally twice daily) help thin secretions to improve clearance, though routine aerosolized use is not universally recommended.^[82] These interventions are tailored based on sputum characteristics and patient tolerance.^[83] Refractory chronic cough warrants multidisciplinary referral to specialized cough clinics, where pulmonologists, otolaryngologists, speech therapists, and gastroenterologists collaborate to refine diagnostics and personalize treatment. These clinics employ comprehensive evaluations to manage complex cases, improving outcomes through integrated care.^[84] Ongoing monitoring is essential to assess treatment response and cough burden. Patients maintain cough diaries to track frequency, triggers, and severity, while validated quality-of-life tools like the Leicester Cough Questionnaire (LCQ) or Severity of Chronic Cough Diary (SCCD) quantify impacts on daily functioning and psychological well-being, guiding adjustments in therapy.^[85]^[86]

Emerging Therapies

Emerging therapies for refractory chronic cough target the neural hypersensitivity underlying the condition, focusing on afferent nerve signaling pathways in the airways and vagus nerve. These interventions aim to interrupt aberrant cough reflexes rather than addressing underlying causes like inflammation or infection. Recent advancements from 2023 to 2025 emphasize selective antagonists and non-pharmacological tools, offering hope for patients unresponsive to conventional treatments.^[87] P2X3 receptor antagonists represent a breakthrough in pharmacological management by blocking purinergic signaling in airway sensory neurons, which contributes to cough hypersensitivity. Gefapixant, the first agent in this class, received European Union approval in September 2023 for treating refractory chronic cough in adults, following positive results from phase 3 trials demonstrating a statistically significant reduction in 24-hour objective cough frequency of approximately 18-20% compared to placebo at 45 mg twice daily. As of November 2025, gefapixant has not received FDA approval in the United States.^[88]^[89] Despite its modest efficacy in objective measures, gefapixant improved patient-reported outcomes in cough severity and urge-to-cough, though common side effects include taste disturbances affecting up to 60% of users.^[90] Camlipixant, a next-generation P2X3 antagonist, is in phase 3 trials, with data from the SOOTHE phase 2b study showing a 34% placebo-adjusted reduction in 24-hour cough frequency at doses of 50 mg and 200 mg twice daily, alongside improvements in cough severity scores and an acceptable safety profile.^[91]^[92] TRPV1 modulators, which target transient receptor potential vanilloid 1 channels on sensory afferents, are under investigation to desensitize cough-evoking nerves in the airways. These agents, including inhaled or oral formulations, aim to reduce hypersensitivity by downregulating TRPV1-mediated responses to irritants, building on preclinical evidence that TRPV1 activation drives chronic cough reflexes.^[93] Although early clinical trials, such as those with XEN-D0501, did not meet efficacy endpoints for refractory cough, ongoing investigational efforts explore combination therapies or novel agonists for sustained desensitization without the side effects of hyperthermia or cardiovascular risks seen in first-generation compounds.^[94] Digital therapeutics have gained traction as accessible, non-invasive options for behavioral modification in chronic cough. Internet-based behavioral cough suppression therapy (IBCST) delivers guided exercises and monitoring via online platforms to retrain cough reflexes and reduce awareness of the urge-to-cough. A 2025 randomized controlled trial showed clinically significant improvements in cough-related quality of life (Leicester Cough Questionnaire scores improved by a mean of 3.74-4.1 points in 72-76% of participants) and trends toward reduced cough severity, with high user adherence due to its remote format.^[95]^[96] Neural signaling inhibitors, including biologics directed at vagal pathways, are in early-stage development to modulate central and peripheral cough circuits. These agents target neuropeptides or cytokines involved in vagal afferent hypersensitivity, with preclinical models showing suppression of cough-like reflexes through inhibition of NTS neurons. Early 2025 trials of monoclonal antibodies against TRPV1-upstream mediators reported preliminary reductions in cough sensitivity, though larger studies are needed to confirm efficacy and safety in humans.^[97]^[98] Genomic studies in 2024 identified variants in neuronal ion channels, such as KCNA10, contributing to cough hypersensitivity in chronic dry cough. Future gene therapy approaches may target such genetic factors, drawing on preclinical advances in inhalation delivery of nucleic acid therapies to silence hypersensitive genes like those in TRP channels for long-term desensitization of cough afferents without systemic effects.^[99]^[100] Despite these innovations, access to emerging therapies remains challenged by high costs and limited availability, as discussed at CHEST 2025, which highlighted digital interventions for broader equity and the need for reimbursement pathways for approved agents like gefapixant in high-income settings.^[96]^[101] Ongoing trials and policy discussions aim to address disparities, particularly in low-resource regions where neural-targeted treatments could transform management of refractory cases.^[101]

Epidemiology

Global Prevalence

Acute cough, typically lasting less than three weeks and often resulting from viral upper respiratory tract infections, affects a substantial portion of the global adult population annually, with prevalence estimates ranging from 10% to 33% in general population studies.^[102] In primary care settings, acute cough accounts for a significant share of visits, representing up to 50% of consultations for respiratory symptoms in some Western countries, predominantly driven by self-limiting viral etiologies.^[103] Chronic cough, defined as persisting for eight weeks or longer in adults, has a global prevalence of approximately 9.6%, with rates varying widely from 2% to 18% across regions and populations.^[104] This condition is more prevalent among women, who comprise about two-thirds of affected individuals, and reaches up to 10-12% in parts of the United States and Europe.^[105]^[106] Geographic variations in cough prevalence reflect environmental and infectious disease burdens, with higher rates observed in developing countries where air pollution and tuberculosis (TB) contribute significantly; for instance, chronic cough prevalence can exceed 15% in certain South Asian areas like Nepal due to these factors.^[107] In contrast, overall rates are lower in East Asia at around 4.4%, though pollution-related exacerbations elevate local incidences.^[104] TB-endemic regions, particularly in Southeast Asia and Africa, show elevated cough reporting linked to pulmonary infections.^[108] Cough incidence peaks in specific age groups and demographics, with children experiencing higher rates from conditions like croup and pertussis, which cause acute barking or whooping cough episodes often requiring medical attention.^[109] In the elderly, prevalence rises due to chronic obstructive pulmonary disease (COPD), with frequent cough reported in up to 9.3% of older adults, compounded by age-related comorbidities.^[110] Gender disparities persist, with chronic forms disproportionately affecting women across age groups.^[105] The economic burden of cough is considerable, encompassing direct healthcare costs for consultations, diagnostics, and treatments, as well as indirect costs from absenteeism and reduced productivity; studies indicate that chronic cough patients incur substantially higher resource utilization, with mean annual costs per individual exceeding £1,600 in high-income settings, contributing to a global estimate in the tens of billions annually prior to 2020 when scaled by prevalence.^[111]^[112]

Post-Pandemic Trends

Following the COVID-19 pandemic, chronic cough has emerged as a significant sequela in recovered patients, with prevalence exceeding 30% in certain cohorts, particularly those with initial severe disease. A 2023 study in the Journal of the American Medical Association (JAMA) highlighted this trend, attributing persistent cough to neurologic dysfunction rather than primary respiratory pathology, as SARS-CoV-2's interaction with vagal nerve pathways and peripheral receptors like P2X2/P2X3 heightens cough reflex sensitivity.^[113] This neurologic basis has led to increased refractory cases, where cough resists standard treatments, driven by neuroinflammation and the virus's neurotropism, as evidenced by 2024 research in Clinical Microbiology Reviews.^[114] In the context of long COVID, cough affects 10-20% of cases, often persisting for 1-2 years post-infection, contributing to subtypes characterized by multisystem involvement. Recent 2025 data from a cohort study in BMC Infectious Diseases reported cough in 41.2% of long COVID patients at follow-up, with durations extending beyond 12 months in hospitalized survivors, where 29.5% still experienced symptoms.^[115]^[33] Emerging variants, such as the 2025 Nimbus strain (NB.1.8.1), have been associated with prolonged respiratory symptoms including cough, alongside hallmark features like severe sore throat, exacerbating persistence in vulnerable populations.^[116] Global epidemiology of cough has shifted post-2020, with heightened respiratory infection rates fueling outbreaks; for instance, 2025 surveillance indicated elevated cough incidence during surges of influenza, RSV, and COVID-19, reaching up to 39% in affected communities per natural history studies.^[117] Risk factors for cough persistence include pre-existing chronic cough and sputum production, which independently predict long-term symptoms in post-COVID cohorts, as identified in a 2024 Respiratory Medicine analysis.^[118] Vaccination has mitigated these trends, with 2025 data showing reduced severe and persistent cough in vaccinated individuals, lowering long COVID risk by up to 32% for airway diseases through attenuated viral neurotropism.^[119]^[120]

Traditional Medicine

Herbal and Folk Remedies

Throughout history, herbal and folk remedies have been employed to alleviate cough symptoms, with ancient texts documenting their use. The Ebers Papyrus, an Egyptian medical document dating to around 1550 BCE, describes honey as a remedy for coughs and throat ailments, often combined with other natural substances for soothing effects.^[121]^[122] Similarly, ancient Egyptian practices utilized honey's healing properties to treat respiratory issues, reflecting early empirical observations of its benefits.^[123] Thyme and ivy leaf extracts are among the most studied herbal remedies for cough relief, valued for their mucolytic and antitussive properties that help thin mucus and reduce coughing frequency. These extracts work by relaxing bronchial smooth muscles and promoting expectoration, as demonstrated in clinical studies showing reduced cough fits by up to 68% compared to placebo.^[124] A 2021 observational study further confirmed their efficacy in acute upper respiratory tract infections, particularly for adults experiencing bronchitis-related cough.^[125] Honey, often mixed with lemon, serves as a traditional soothing remedy for cough, leveraging honey's antibacterial and demulcent qualities to coat the throat and suppress irritation. Systematic reviews of RCTs indicate that honey provides modest relief for acute cough in children over one year old, reducing nighttime coughing and improving sleep more effectively than usual care or over-the-counter options; current accumulating evidence suggests that honey might have a role in treating cough and cold in children, a recommendation made by the World Health Organization.^[126]^[127] Lemon enhances this by providing vitamin C and aiding in mucus clearance, though evidence for the combination specifically remains supportive rather than definitive.^[128] In Ayurvedic traditions, ginger and turmeric are utilized for their anti-inflammatory effects to mitigate cough associated with colds and inflammation. Ginger's active compounds, such as gingerol, exhibit anti-inflammatory and expectorant actions, helping to reduce airway irritation as noted in traditional texts and supported by modern reviews of herbal use in respiratory symptom management.^[129] Turmeric, containing curcumin, is similarly prescribed in Ayurveda for its potent anti-inflammatory properties, which may alleviate cough by inhibiting inflammatory mediators in the respiratory tract.^[130] A 2023 review highlights their combined role in Ayurvedic formulations for common cold symptoms, including cough, with preliminary evidence from RCTs showing reduced inflammation markers.^[129] Overall, systematic reviews of RCTs demonstrate modest efficacy for these herbal remedies in acute cough, with thyme-ivy combinations and honey showing the strongest evidence for symptom reduction, though benefits are generally short-term and vary by individual.^[131] Safety considerations are crucial; while most are well-tolerated, honey poses a significant risk of infant botulism due to Clostridium botulinum spores and is contraindicated for children under one year.^[132] Potential interactions with medications or allergies should be monitored, particularly for ginger and turmeric in those with gastrointestinal sensitivities.^[133]

Cultural Practices

Steam inhalation has been a longstanding practice in European folk medicine to alleviate respiratory congestion associated with coughs. Inhaling warm steam is recommended to clear airways and provide symptomatic relief during colds that often involve coughing. This method involves breathing in steam from hot water, sometimes enhanced with saline, to moisten and soothe irritated mucous membranes. In Traditional Chinese Medicine (TCM), cupping and moxibustion are employed as non-herbal techniques to promote airway clearance and reduce cough symptoms. Cupping therapy, which creates suction on the skin using glass cups, is applied to back points to improve lung function and expel pathogens causing respiratory issues, as evidenced in treatments for severe coughs following infections. Moxibustion, involving the burning of mugwort near acupoints, warms the lungs and resolves phlegm to stop chronic coughs, particularly in children, by enhancing qi flow and reducing inflammation. These practices are often used together to address underlying imbalances leading to persistent coughing. Dietary approaches in various cultures emphasize warm soups to soothe the throat and ease cough irritation. In Jewish traditions, chicken soup, known as "Jewish penicillin," is a folk remedy that provides warmth and hydration to relieve cold symptoms, including coughs, through its steaming vapors and nutrient-rich broth. Similarly, in Asian traditions, particularly Chinese, warming soups like those with ginger and chicken are consumed to moisturize the lungs, soothe throat irritation from excessive coughing, and promote recovery from respiratory illnesses. Certain rituals in indigenous practices involve avoiding cold foods and drinks during respiratory illnesses to prevent exacerbating symptoms. Among Tarascan indigenous communities in Mexico, consuming "cold" foods is believed to cause or worsen gripa (colds with cough), leading to rituals that favor "hot" foods for balance and healing. In Filipino indigenous health beliefs, cold drinks and cooling foods are strictly avoided during illness to maintain body heat and support recovery from conditions like coughs. These cultural practices are increasingly integrated into modern complementary therapies for cough management, with high acceptability reported in recent studies. Such integrations highlight their role in holistic approaches, often alongside brief herbal supports for enhanced symptom relief.

Cough in Other Animals

Veterinary Perspectives

In veterinary medicine, cough in domestic animals, particularly dogs and cats, is a common clinical sign indicating irritation or inflammation of the respiratory tract, often requiring prompt evaluation to identify underlying causes such as infectious or parasitic diseases.^[134] Among dogs, kennel cough, also known as canine infectious respiratory disease complex (CIRDC), is a prevalent condition primarily caused by Bordetella bronchiseptica in combination with viral pathogens like canine parainfluenza virus, leading to acute bronchitis.^[135] Recent outbreaks of atypical CIRDC (aCIRDC) have been reported in the United States and other regions from 2023 to 2025, characterized by severe pneumonia in some cases unresponsive to standard antibiotics; investigations as of 2025 have not identified novel pathogens, but incidence remains elevated in certain areas.^[136]^[137] Heartworm disease, caused by Dirofilaria immitis, is another significant cause in dogs, where adult worms in the pulmonary arteries provoke chronic respiratory inflammation and coughing.^[138] In cats, cough is less frequent but often stems from lower respiratory tract inflammation, such as feline bronchitis or asthma, with Bordetella bronchiseptica occasionally implicated in upper respiratory infections.^[139]^[134] Clinical symptoms vary by species and etiology; in dogs with kennel cough, a characteristic dry, honking cough is typical, often triggered by excitement or pressure on the trachea, while heartworm-associated cough is softer, persistent, and worsens with exercise.^[135]^[140] Cats may exhibit wheezing or a softer, hacking cough, particularly in cases of bronchitis or parasitic migration, accompanied by open-mouth breathing or lethargy if severe.^[141] These signs resemble the human cough reflex in serving as a protective mechanism to clear airways, though veterinary assessment focuses on species-specific patterns.^[142] Diagnosis begins with physical examination, including thoracic auscultation to detect abnormal lung sounds like crackles or wheezes, which can localize the issue to upper or lower airways.^[142] Thoracic radiographs are essential for visualizing pulmonary infiltrates, heart enlargement in heartworm cases, or bronchial patterns in inflammatory disease, often followed by fecal or serologic tests for parasites.^[143] Endoscopy, including bronchoscopy, allows direct visualization of tracheal collapse or foreign bodies, particularly useful in chronic cases unresponsive to initial therapy.^[144] Treatment strategies prioritize supportive care, such as rest, humidified air, and cough suppressants like dextromethorphan to reduce irritation, while addressing the underlying cause.^[145] Antibiotics, such as doxycycline, are indicated for confirmed bacterial infections like Bordetella, typically administered for 7-14 days, but are avoided in viral-predominant cases to prevent resistance.^[146] For heartworm, adulticide therapy with melarsomine is standard, combined with anti-inflammatory agents to manage coughing during treatment.^[147] In cats, bronchodilators like albuterol may be used for wheezing, with antibiotics reserved for secondary infections.^[134] Cough prevalence is notably high in animal shelters, where outbreaks of CIRDC can affect a substantial portion of dogs, with studies reporting up to 48% of asymptomatic dogs carrying pathogens that contribute to disease spread.^[148] Breed predispositions exacerbate risks; brachycephalic dogs, such as Bulldogs and Pugs, experience more frequent coughing from conformational airway obstruction, increasing susceptibility to infections.^[149] Zoonotic concerns arise with certain pathogens, as dogs and cats can transmit avian influenza (H5N1) to humans through close contact, particularly in households with exposure to infected birds.^[150]^[151]

Comparative Physiology

In mammals, the cough reflex is mediated by a conserved vagal afferent pathway, where sensory neurons detect irritants in the airways and trigger explosive expulsion through the glottis to clear secretions and foreign particles.^[152] This mechanism varies in glottis control across species; for instance, horses with recurrent airway obstruction often exhibit frequent coughing to clear mucus-laden airways.^[153] Birds possess a unique unidirectional respiratory system featuring air sacs that connect to the lungs, altering the dynamics of air expulsion compared to mammalian tidal breathing. This structure facilitates rapid clearance of dust and particulates from the respiratory tract, often through sneeze-like behaviors rather than a traditional cough, as the air sacs enable efficient unidirectional airflow to minimize re-inhalation of irritants. In reptiles and amphibians, coughing is less frequent and less developed, with many species relying on buccopharyngeal pumping—a force-pump mechanism using the mouth and throat muscles—for lung ventilation and limited irritant expulsion, rather than a dedicated cough reflex.^[154] This pumping action, inherited from early vertebrates, supports intermittent air breathing but lacks the diaphragmatic support for explosive coughs seen in mammals.^[155] Evolutionarily, the cough reflex serves a conserved role in airway protection across vertebrates, expelling pathogens, allergens, and aspirate to prevent aspiration, though its intensity and form adapt to environmental pressures; in cetaceans like whales, underwater living has led to specialized anatomical adaptations such as valved blowholes and separate nasal and oral pathways, reducing reliance on coughing by minimizing water entry during surfacing breaths.^[156]^[157] Recent evolutionary studies on P2X receptor homologs in fish highlight conserved ATP-sensing mechanisms in sensory neurons, providing insights into the origins of hypersensitivity responses that parallel cough sensitization in higher vertebrates.^[158] A key difference lies in cough control, where humans uniquely possess the ability to initiate voluntary coughs alongside involuntary reflexes, mediated by higher cortical integration of vagal signals, whereas most animals exhibit only involuntary responses triggered by peripheral stimuli.^[159]

References

[1]
Cough - StatPearls - NCBI Bookshelf - NIH
Coughing is a largely uncontrolled, protective reflex mechanism responsible for mucociliary clearance of the airway and excess secretions within the airway.
[2]
Cough - Mayo Clinic
A cough is your body's way of responding when something irritates your throat or airways. An irritant stimulates nerves that send a message to your brain.
[3]
Chronic cough - Symptoms and causes - Mayo Clinic
Oct 29, 2024 · A chronic cough is a cough that lasts eight weeks or longer in adults, or four weeks in children. A chronic cough is more than just annoying.
[4]
Cough: Causes, Types, Diagnosis & Treatment - Cleveland Clinic
A cough is a forceful push of air that your body uses to clear irritants, mucus and germs out of your airways. Common causes include allergies, asthma, ...Missing: reliable | Show results with:reliable
[5]
Learn About Coughing | American Lung Association
Jul 30, 2025 · A cough is a spontaneous reflex. When things such as mucus, germs or dust irritate your throat and airways, your body automatically responds by coughing.Missing: reliable | Show results with:reliable
[6]
An Office Approach to the Diagnosis of Chronic Cough | AAFP
Dec 1, 1998 · Characteristics such as paroxysmal, barking, honking, brassy, self-propagating, loose or productive, and nocturnal, postprandial, or occurring ...
[7]
Diagnosis and Management of Cough Executive Summary - CHEST
1. In every patient with cough, when taking a medical history, ask about occupational and environmental causes. Level of evidence, expert opinion; benefit ...Summary And Recommendations · Cough And The Common Cold · Postinfectious Cough<|control11|><|separator|>
[8]
Chronic Cough - StatPearls - NCBI Bookshelf
Cough is a complex reflex involving coordination between various muscles and neural pathways. Coughing is a protective mechanism for the respiratory system, ...
[9]
Evaluation of the Patient with Chronic Cough | AAFP
Oct 15, 2011 · Acute cough lasts up to three weeks, subacute cough lasts three to eight weeks, and chronic cough lasts longer than eight weeks.
[10]
Classification of Cough as a Symptom in Adults and Management ...
Oct 25, 2017 · 2. For adult patients complaining of cough, we suggest that subacute cough be defined as being between 3 and 8 weeks in duration (Grade 2C).
[11]
Bronchitis - Symptoms and causes - Mayo Clinic
Jul 31, 2024 · Sore throat; Mild headache and body aches; Slight fever and chills; Fatigue; Chest discomfort; Shortness of breath and wheezing. While these ...
[12]
Cough as a neurological sign: What a clinician should know - PMC
INTRODUCTION. Cough is a forced expiratory effort against a closed glottis that opens suddenly with the expulsion of secretion and foreign particles out of the ...Introduction · Vagal Neuropathy · Cough Syncope
[13]
Clinical features of the urge-to-cough in patients with chronic cough
The somatic sensations associated with the urge-to-cough were described as an irritation (86%) or tickle (73%), localised in the neck (75%).
[14]
https://journal.chestnet.org/article/S0012-3692(15)52831-6/fulltext
[15]
Life-Threatening and Non-Life-Threatening Complications ...
On the other hand, coughing can also lead to atrioventricular block and other arrhythmias (Table 1). Table 1. Cough-Associated Complications. System Category ...
[16]
Cough, a vital reflex. Mechanisms, determinants and measurements
Cough is a reflex arc, which acts as a defensive physiological mechanism against the inhalation of foreign bodies and the pathogens of the respiratory tract.
[17]
Cough Reflex TeachMePhysiology
Jul 16, 2023 · The cough reflex is an important defence mechanism which clears the airways of irritants by forcefully expelling air from the respiratory tract.
[18]
Anatomy and neuro-pathophysiology of the cough reflex arc - PMC
The cough center generates an efferent signal that travels down the vagus, phrenic, and spinal motor nerves to expiratory musculature to produce the cough. ...
[19]
Cough Reflex
The cough reflex has 5 components: 1) cough receptors, 2) afferent nerves, 3) a poorly defined cough center, 4) efferent nerves, 5) effector muscles. ... central ...
[20]
Peripheral Neural Circuitry in Cough - PMC - PubMed Central - NIH
The hallmark of C fiber nociceptive afferents is sensitivity to capsaicin due to the expression of TRPV1 in nociceptors [44]. Capsaicin activates airway C ...
[21]
ATP, an attractive target for the treatment of refractory chronic cough
Jun 21, 2022 · The antitussive effects of P2X3 antagonists, which suppress the ATP-mediated sensitization of nociceptors, provide potent evidence for ATP-P2X3 ...
[22]
Peripheral and central mechanisms of cough hypersensitivity - PMC
In this review, we explore the current peripheral and central neural mechanisms that are believed to be involved in altered cough sensitivity.
[23]
The search for the hypersensitivity in chronic cough - ERS Publications
In some patients, central sensitisation and loss of inhibitory cortical activity may be important in the development of CHS [8]. There are a number of ...<|separator|>
[24]
Dynamics of Voluntary Cough Maneuvers: A Theoretical Model
The high-speed airflow can apply a very large shear stress on the mucus layer causing its removal from the lungs. While the above cough components are well ...Missing: velocity mph forces
[25]
Post-COVID Cough Linked to Neurological Dysfunction | MDedge
Feb 14, 2025 · The virus stimulates the vagus nerve, which activates the cough reflex. Research suggests that neurotropism, neuroinflammation, and ...
[26]
Gender Difference in Chronic Cough: Are Women More Likely to ...
Chronic cough is a common complaint for patients to seek medical cares all over the world. Worldwide, about two thirds of chronic cough patients are females.
[27]
Modification of oestrogen signalling pathways influences cough ...
Differences in cough sensitivity between boys and girls appear in mid and late puberty and are very likely associated with increased production of female ...
[28]
Kappa and Mu Opioid Receptors in Chronic Cough
May 13, 2025 · Drugs with a dual-acting mechanism of kappa receptor agonism and mu receptor antagonism may be effective in the management of chronic cough ...
[29]
NMDA and GABA receptors as potential targets in cough ...
Antitussive therapies based on opioid medications are generally not efficacious. Antagonists of N-methyl-d-aspartate receptors in the brain stem and use of GABA ...
[30]
Infections of the Respiratory System - Medical Microbiology - NCBI
Viruses cause most cases of bronchitis and bronchiolitis. In community-acquired pneumonias, the most common bacterial agent is Streptococcus pneumoniae.Missing: parasitic | Show results with:parasitic
[31]
Overview of Viral Respiratory Infections - Infectious Diseases
The majority of cases are caused by rhinoviruses, but some are caused by coronaviruses, influenza viruses, or other viruses. Diagnosis is clinical.
[32]
Long-Term Clinical Outcomes of Adults Hospitalized for COVID-19 ...
May 20, 2025 · At 12 months, 51 (29.5%) participants reported cough, 60 (34.7%) reported dyspnea, 56 (32.4%) had residual lung texture abnormalities on high- ...
[33]
Long COVID-19: a Four-Year prospective cohort study of risk factors ...
Aug 30, 2025 · Fatigue (57.1%), post-exertional malaise (45.8%), cough (41.2%), and cognitive dysfunction (30.7%) were the most common persistent symptoms.
[34]
Environmental and Health Impacts of Air Pollution: A Review - PMC
Feb 20, 2020 · Particulate contaminants include contaminants such as smog, soot, tobacco smoke, oil smoke, fly ash, and cement dust.
[35]
The Respiratory Risks of Ambient/Outdoor Air Pollution - PMC
Several studies have documented the increased risk of respiratory infection associated with air pollution exposure. The odds of acute lower respiratory tract ...Missing: epidemics | Show results with:epidemics
[36]
The Potential Impact of Smog Spell on Humans' Health Amid COVID ...
Some of the major diseases which are harbored by smog are respiratory diseases (asthma, coughing, and bronchiolitis), cardiovascular disease, neurological ...
[37]
Occupational exposure to dust: an underestimated health risk? - NIH
Occupational exposure to dust, even at low doses, is a risk to workers' health because it is significantly associated with respiratory symptoms.
[38]
Effect of Exposure to Cement Dust among the Workers - NIH
A study based on Malaysian population reported the association of total dust exposure and respiratory symptoms such as a cough, phlegm, chest tightness and also ...
[39]
Occupations and exposure events in acute and subacute irritant ...
Mar 31, 2021 · Usually, IIA is work-related and accounts for 5%–18% of all occupational asthma cases. Irritants are less known than sensitisers as causative ...Missing: cough | Show results with:cough
[40]
Chronic Bronchitis - StatPearls - NCBI Bookshelf
Feb 6, 2025 · Chronic bronchitis results from prolonged exposure to irritants that damage the lungs, with smoking being the primary cause. Among current ...
[41]
Chronic Cough Due to Chronic Bronchitis: ACCP Evidence-Based ...
Conclusions: Chronic bronchitis due to cigarette smoking or other exposures to inhaled noxious agents is one of the most common causes of chronic cough in the ...
[42]
The impact of cold on the respiratory tract and its consequences to ...
May 30, 2018 · Cold-induced airway damage is not only due to the direct effect of temperature, but also depends on the hyperventilation. Cooling of the airways ...
[43]
Climate change, air pollution and extreme events leading to ...
The most abundant components of air pollution in urban areas are nitrogen dioxide, ozone and particulate matter. Sulphur dioxide is particularly abundant in ...
[44]
Foreign body aspiration in children: experience from 2624 patients
Results: The children (62.34% males and 37.65% females) were aged 4 months to 18 years with 66% between 1 and 3 years. Choking was related in 65% of cases. The ...Missing: hazards prevalence
[45]
Foreign body aspiration in adult airways: therapeutic approach - PMC
FB aspiration is an uncommon but potentially life-threatening event in adults. Symptoms typically consist of a choking event followed by cough and dyspnea.
[46]
Between two storms, vasoactive peptides or bradykinin underlie ...
Among the most recognized examples of adverse side effects afforded by ACE inhibitors are cough (experienced by 5–20% of patients) and angioedema (experienced ...Missing: prevalence | Show results with:prevalence
[47]
Ace revisited: A new target for structure-based drug design - PMC
Side effects of treatment with ACE inhibitors include cough and angioedema. ... The incidence of cough has been estimated at 5–20% of patients and might ...
[48]
Chronic Cough: Evaluation and Management | AAFP
Nov 1, 2017 · It should also rule out red flags (e.g., fever, weight loss, hemoptysis, hoarseness, excessive dyspnea or sputum production, recurrent ...
[49]
https://www.aafp.org/pubs/afp/issues/2017/1101/p575.html
[50]
Clinical Practice Guidelines for Diagnosis and Management of ...
Acute cough is defined as cough lasting for <3 weeks, subacute cough lasts 3–8 weeks, and chronic cough persists for >8 weeks (6). Cough can also be categorized ...
[51]
Standardization of Spirometry 2019 Update. An Official American ...
It is widely used in the assessment of lung function to provide objective information used in the diagnosis of lung diseases and monitoring lung health. In 2005 ...
[52]
Sputum Analysis - StatPearls - NCBI Bookshelf - NIH
May 4, 2025 · The sputum analysis involves an analytical approach to investigate the cellular and acellular components expelled from the patient's upper respiratory tract.
[53]
Reflux-Cough Syndrome: Guidelines from the ACCP - AAFP
Nov 1, 2017 · Esophageal manometry and pH-metry are recommended for certain adults with chronic cough if the cough is thought to be reflux related.
[54]
Guidelines for the Diagnosis and Management of Gastroesophageal ...
We suggest that upper endoscopy should not be used as the method to establish a diagnosis of GERD-related asthma, chronic cough, or LPR. Low, Conditional. We ...
[55]
Flexible bronchoscopy in the diagnosis of chronic cough causes in ...
Flexible bronchoscopy is a useful tool for diagnosing rare causes of chronic cough in adults, but it should be performed as a second-step investigation.
[56]
Allergic rhinitis | Allergy, Asthma & Clinical Immunology | Full Text
Dec 27, 2024 · Skin-prick testing is considered the primary method for identifying specific allergic triggers of rhinitis. It involves pricking the skin ...
[57]
Role of Skin Prick Test in Allergic Disorders - NIH
Skin prick test (SPT) is the most effective diagnostic test to detect IgE mediated type I allergic reactions like allergic rhinitis, atopic asthma, acute ...
[58]
Novel capsaicin cough endpoints effectively discriminate between ...
Dose-response capsaicin cough challenges are safe, reproducible and tolerable. · Maximum cough response endpoints can discriminate health from chronic cough.
[59]
Comparison of different nebulisation systems for capsaicin cough ...
To the Editor: Cough challenge testing is an established research tool that has been used for many decades to experimentally induce cough in humans [1].
[60]
Cough - PMC - NIH
Based on duration, cough is classified as acute (<3 weeks), subacute (3–8 weeks), and chronic (>8 weeks). Duration of symptoms is key because acute, subacute, ...
[61]
Cough and Sputum Production - Clinical Methods - NCBI Bookshelf
Definition. A cough is a sudden, usually involuntary, expulsion of air from the lungs with a characteristic and easily recognizable sound.
[62]
WAO-ARIA consensus on chronic cough - Part II: Phenotypes and ...
Upper and lower airway etiologies of chronic cough are collectively termed upper airway cough syndrome (UACS) and lower airway cough syndrome (LACS) ...
[63]
Cough-hypersensitivity Syndrome-A New Paradigm in the ...
Definition, irritation/itch/scratchy throat, cough triggered by non-cough stimulant ; Examples, Tickle, Talking, Laughing ; Globus sensation, Singing, Changing ...
[64]
Cough hypersensitivity and chronic cough - PMC - PubMed Central
Jun 30, 2022 · Sensations in the larynx (laryngeal paraesthesia) or chest such as tickle, itch or irritation can trigger coughing and can be more bothersome ...
[65]
The Spectrum of Non-asthmatic Airway Diseases Contributing to ...
Recent Findings. Acute cough syndrome is short-lived and self-limited. Acute bronchitis and diffuse acute infectious bronchiolitis (DAIB) are examples. The ...Acute Bronchitis · Chronic Bronchitis · Bronchiolitis<|control11|><|separator|>
[66]
Cough in idiopathic pulmonary fibrosis - PMC - PubMed Central
Chronic cough in IPF is not only often refractory, but is also an independent predictor of disease progression [5]. Better understanding of the underlying ...Missing: classification | Show results with:classification
[67]
Humidifiers and health: MedlinePlus Medical Encyclopedia
Oct 20, 2024 · Using a humidifier in the home can help relieve a stuffy nose and can help break up mucus so you can cough it up. Humidified air can relieve ...
[68]
Honey for acute cough in children - a systematic review - PubMed
Jun 25, 2023 · We found low quality evidence that honey may be more effective than cough medication or placebo/no treatment in relieving symptoms and improving sleep in ...
[69]
Diagnosing and Treating a Cough | American Lung Association
Jul 30, 2025 · How Cough Is Diagnosed · When did your cough start? · Does your cough bring up mucus? · If there is mucus, what's the consistency and color? · Do ...
[70]
Guidelines for Treating Adults with Acute Cough - AAFP
Feb 15, 2007 · A history, physical examination, and selected diagnostic testing can help physicians accurately diagnose patients who will likely benefit ...<|control11|><|separator|>
[71]
Chest Cold (Acute Bronchitis) Basics - CDC
Apr 17, 2024 · Cough keeping you up at night? Soreness in your chest and feeling tired? You could have a chest cold, often called acute bronchitis.Missing: wheezing | Show results with:wheezing
[72]
ERS guidelines on the diagnosis and treatment of chronic cough in ...
We suggest a short-term anti-leukotriene trial (2-4 weeks) in adult patients with chronic cough, particularly in those with asthmatic cough (conditional ...
[73]
Speech and language therapy for management of chronic cough
The patient is taught to substitute the cough with a competing response (e.g. distraction, cough suppression swallow, relaxed throat breathing, a sip of fluids, ...
[74]
Treatment of Unexplained Chronic Cough: CHEST Guideline and ...
Speech pathology-based cough suppression is suggested as a treatment option for UCC. This guideline presents suggestions for diagnosis and treatment.
[75]
Use of Specific Neuromodulators in the Treatment of Chronic ...
Jan 8, 2013 · Conclusion. Benefit from neuromodulator treatment with amitriptyline, gabapentin, pregabalin, and baclofen in chronic, idiopathic cough patients ...
[76]
An update and systematic review on drug therapies for the treatment ...
Each of the centrally acting neuromodulators (amitriptyline, gabapentin, pregabalin, morphine, and tramadol) that we reviewed had positive effects on cough- ...
[77]
Acetylcysteine for Patients Requiring Secretion Clearance - NCBI
Jul 3, 2019 · The purpose of this report is to review the evidence-based guidelines regarding the use of acetylcysteine for patients requiring mucous secretion clearance.
[78]
AARC Clinical Practice Guideline: Effectiveness of Pharmacologic ...
Dec 17, 2024 · The routine use of aerosolized N-acetylcysteine to improve airway clearance is not recommended. Aerosolized agents to change mucus biophysical ...Assessment Of Evidence · Hospitalized Adult And... · Postoperative Adult And...
[79]
Consensus goals and standards for specialist cough clinics
Nov 20, 2023 · Specialist cough clinics should be established to provide the optimal care for patients with chronic cough and refractory cough. 84.9. 2, Aims ...
[80]
The Severity of Chronic Cough Diary (SCCD) - PubMed Central - NIH
Jul 10, 2023 · In addition to physical effects, RCC can have a substantial impact on patients' health-related quality of life (HRQoL) [3, 4]. Primary endpoints ...
[81]
Evaluating Cough Assessment Tools - CHEST Journal
The LCQ and CQLQ for adults and the Parent Cough-Specific Quality of Life questionnaire for children are valid instruments for assessing cough impact. There is ...
[82]
Chronic cough: is the end nigh? | European Respiratory Society
Gefapixant is the first P2X3 receptor antagonist to successfully complete phase 3 trials and as of late 2023, has been approved for use in the European Union, ...
[83]
Merck Receives Positive European Union CHMP Opinion for ...
Jul 21, 2023 · Both studies met the primary endpoint, demonstrating a statistically significant reduction in 24-hour cough frequency in adults treated with ...
[84]
Merck's Gefapixant for Chronic Refractory Cough | Key Insights
Feb 6, 2023 · While gefapixant 45 mg twice per day showed significant reductions of 18.5% and 14·6% in 24-h cough frequency compared with placebo at week 12 ...<|separator|>
[85]
What role for gefapixant in chronic cough?
In the two main licensing studies, gefapixant produced only a small additional effect over placebo in reducing the number of coughs over 24 hours.
[86]
Camlipixant: A New Hope for Refractory Chronic Cough?
Gefapixant demonstrated statistically significant results in two phase III studies without serious adverse events, although nearly two-thirds of patients ...
[87]
Camlipixant safe, yields improvements in refractory chronic cough
Apr 1, 2025 · Adults with refractory chronic cough who received twice-daily camlipixant had decreases in cough frequency and better scores assessing cough severity.
[88]
Mechanisms and Rationale for Targeted Therapies in Refractory ...
Aug 4, 2020 · In addition to TRPV1 antagonism, the ability of oral capsaicin to induce desensitization of the cough reflex through TRPV1 has also been ...<|separator|>
[89]
XEN-D0501, a Novel Transient Receptor Potential Vanilloid 1 ...
Apr 18, 2017 · This study rules out TRPV1 as an effective therapeutic target in patients with refractory chronic cough.
[90]
Internet-Based Behavioral Cough Suppression Therapy for ...
Purpose:The purpose of this study was to assess the efficacy of internet-based behavioral cough suppression therapy (IBCST) and explore users' experiences.
[91]
CHEST 2025: Improving Access to Chronic Cough Treatment ...
Oct 22, 2025 · Slovarp noted that early findings showed approximately a 40% reduction in cough frequency and significant improvements in quality of life, ...Missing: IBCST | Show results with:IBCST
[92]
A vagal–brainstem interoceptive circuit for cough-like defensive ...
Jul 8, 2024 · We propose that these Tac1 neurons in the NTS are a key component of the airway–vagal–brain neural circuit that controls cough-like defensive ...
[93]
Chronic cough: A review and prospects - Medicine
Oct 10, 2025 · Capsaicin-sensitive vagal neurons have emerged as the key targets of the cough-specific neural circuit.
[94]
Genomics of chronic dry cough unravels neurological pathways - PMC
Sep 25, 2025 · Our findings provide support for neuronal dysfunction underlying cough hypersensitivity in chronic dry cough and ACEi-induced cough, and ...
[95]
Inhalation delivery of nucleic acid gene therapies in preclinical drug ...
Oct 4, 2025 · Respiratory diseases have long been attractive targets for gene therapy due to the relative ease of delivering treatments directly to the lungs ...<|separator|>
[96]
Guidelines & Topic Collections
This CHEST guideline examines the literature on primary treatment of patients with stage I and II non-small cell lung cancer and consists of 17 evidence-based ...Guidelines Overview · Pulmonary Vascular Disease · Critical Care
[97]
The Diagnosis and Treatment of Acute Cough in Adults - PMC
If the patient insists on treatment, general symptom-relieving agents can be recommended (nonsteroidal anti-inflammatory drugs, decongestant nose drops).
[98]
Prevalence, aetiologies and prognosis of the symptom cough in ...
Jul 12, 2021 · Based on population, the prevalence of cough in Europe and the USA is 9–33% [1]. Severe cough can significantly impair health-related quality of ...
[99]
The global epidemiology of chronic cough in adults: a systematic ...
The primary finding was a high global prevalence (9.6%), comparable to that reported for asthma or chronic obstructive pulmonary disease [14, 15].
[100]
A worldwide survey of chronic cough: a manifestation of enhanced ...
Of the 10 032 patients presenting with chronic cough, two-thirds (6591) were female (mean age 55 years). The patient profile was largely uniform across centres.
[101]
Prevalence, clinical characteristics, and disease burden of chronic ...
Jun 20, 2024 · Globally, approximately 10% of adults have chronic cough [1], a protracted and debilitating condition, in which over 40% of affected adults ...
[102]
Burden of asthma, dyspnea, and chronic cough in South Asia
Apr 6, 2017 · Prevalence of asthma was highest in India (6.3%), while Nepal had the highest prevalence of dyspnea (11.3%) and chronic cough (15.3%). Overall ...
[103]
Global, regional and national trends in tuberculosis incidence and ...
Jan 2, 2024 · The spatial distribution of TB incidence exhibits significant regional variations. Southeast Asia and Africa account for nearly 70% of all ...
[104]
Cough: are children really different to adults? - PMC - PubMed Central
Infections such as pertussis and mycoplasma can cause persistent cough not associated with other symptoms [123]. Pertussis should be suspected especially if the ...Missing: elderly | Show results with:elderly
[105]
Cough in the Elderly Population: Relationships with Multiple ...
The prevalence of cough was 9.3% for frequent cough, 4.6% for chronic persistent cough, and 7.3% for nocturnal cough. Female subjects had more frequent ...
[106]
Full article: Healthcare utilization and costs in chronic cough
The mean (SD) total cost per individual for cough-related healthcare utilization was £1,663 (747). Diagnostic investigations were the largest contributor to ...
[107]
Understanding the economic burden of chronic cough: a systematic ...
Oct 31, 2023 · This systematic literature review (SLR) sought to identify evidence on the cost-effectiveness of treatments and the economic burden associated with CC.Missing: pre- | Show results with:pre-
[108]
Development of a Definition of Postacute Sequelae of SARS-CoV-2 ...
May 25, 2023 · This study aims to develop a definition of postacute sequelae of SARS-CoV-2 infection (PASC) based on self-reported symptoms and describe ...
[109]
Neurological complications caused by SARS-CoV-2 - ASM Journals
Sep 18, 2024 · Confronting COVID-19-associated cough and the post-COVID syndrome: role of viral neurotropism, neuroinflammation, and neuroimmune responses.
[110]
Long COVID-19: a Four-Year prospective cohort study of risk factors ...
Aug 30, 2025 · The most frequently reported symptoms among patients with long COVID-19 were fatigue (57.1%), post-exertional malaise (45.8%), cough (41.2%), ...
[111]
https://www.tandfonline.com/doi/full/10.1080/03007995.2022.2065142
[112]
Natural course of post-COVID symptoms in adults and children
Feb 16, 2024 · This study aimed to explore the natural course of post-COVID symptoms and reveal the prevalence and duration of each symptom, both in adults and children.
[113]
Relevant factors associated with the development of chronic cough ...
This study is the first to show that the presence of sputum and chronic cough before contracting COVID-19 are risk factors for chronic cough after recovery.
[114]
Vaccination may reduce elevated risk of airway diseases in COVID ...
Aug 21, 2025 · In contrast, COVID-19 vaccination reduced the risk of asthma by 32.2%, with significant but smaller reductions for allergic rhinitis and chronic ...Missing: post- | Show results with:post-
[115]
The effect of pre-COVID and post-COVID vaccination on long COVID
Our study suggests that 2-dose pre-COVID vaccination and 1-dose post-COVID vaccination are associated with a lower risk of long COVID.
[116]
The Ebers Papyrus: Medico-Magical Beliefs and ... - Ancient Origins
Jul 22, 2019 · The Ebers Papyrus is an ancient medical document that contains over 842 remedies for illnesses and injuries. It specifically focused on the ...<|control11|><|separator|>
[117]
History of medicine - Heart Views
The Ebers Papyrus contains a description on how to make ointment from honey and how to apply it, with a note: "Notice that this is a very good therapy"[6].Honey In Mythology And... · Ancient Writings · Revival Of Honey In Medicine
[118]
Magical honey: some unusual uses in Ancient Egypt - The Past
Aug 8, 2023 · Ancient Egyptians used honey in cooking, especially to sweeten dishes in the absence of sugar, and in medicine, for its healing properties and to soothe coughs.
[119]
Herbal medicine for the treatment of chronic cough - PubMed Central
Oct 17, 2023 · Conclusion: HM may improve cough severity and cough-related quality of life, and lower the cough recurrence rate and incidence of adverse events ...
[120]
Efficacy and tolerability of a fluid extract combination of thyme herb ...
Results: The mean reduction in coughing fits on days 7 to 9 relative to baseline was 68.7% under thyme-ivy combination compared to 47.6 % under placebo (p < ...Missing: antitussive evidence 2023 review<|separator|>
[121]
Effectiveness and tolerability of the thyme/ivy herbal fluid extract ...
A systematic review and meta-analysis confirmed that ivy-, primrose- or thyme-based remedies reduce both frequency and severity of acute coughCitation. Here we ...
[122]
Honey for treatment of cough in children - PMC - PubMed Central
Conclusion. Honey can be recommended as a single dose of 2.5 mL before bedtime for children older that 1 year of age with cough.
[123]
Honey: An effective cough remedy? - Mayo Clinic
Children ages 1 and older can be given 0.5 to 1 teaspoon (2.5 to 5 milliliters) of honey to treat a cough. The honey can be given as is or added to other ...Missing: antibacterial | Show results with:antibacterial
[124]
Coughs and Colds: Medicines or Home Remedies?
Feb 12, 2022 · For children 1 year and older: Consider using honey, 2 to 5 mL, as needed. The honey thins the mucus and loosens the cough. (If you do not have ...Missing: antibacterial | Show results with:antibacterial
[125]
Treatment of the common cold with herbs used in Ayurveda and Jamu
Jun 14, 2023 · The use of four herbs – ginger, liquorice, turmeric and peppermint – for common cold symptom management in Ayurvedic texts, Jamu publications and monographs.
[126]
Turmeric, the Golden Spice - Herbal Medicine - NCBI Bookshelf - NIH
Numerous lines of evidence suggest that turmeric exhibits anti-inflammatory activity. In one study, crude organic extracts of turmeric were found to inhibit ...
[127]
Herbal Medicine for Cough: A Systematic Review and Meta-Analysis
Dec 14, 2015 · Conclusion: This review found strong evidence for A. paniculata and ivy/primrose/thyme-based preparations and moderate evidence for P. sidoides ...
[128]
Botulism Prevention - CDC
May 6, 2024 · We do know that honey is not safe for infants. Honey can contain the bacteria that cause botulism. Do not feed honey to a child who is ...
[129]
Infant botulism following honey ingestion - PMC - NIH
In order to minimise the risk of infantile botulism, it is recommended not to give honey to less than 1 year old. There is a widespread practice of ...
[130]
Coughing in Cats | VCA Animal Hospitals
In cats, coughing is usually a sign of an inflammatory problem affecting the lower respiratory tract, especially some form of bronchitis. This inflammation is ...
[131]
Canine infectious respiratory disease complex (Kennel cough)
The classic sign of CIRDC is a frequent, honking cough that comes on suddenly. This cough has also been described as gagging or retching, and it can involve ...
[132]
Heartworm in Dogs
Signs of heartworm disease may include a mild persistent cough, reluctance to exercise, fatigue after moderate activity, decreased appetite, and weight loss.
[133]
Bordetella Infections in Dogs and Cats: Pathogenesis, Clinical Signs ...
Bordetella bronchiseptica is a common cause of respiratory infection in dogs and cats. The disease has a high morbidity but low mortality and is diagnosed in ...
[134]
Kennel Cough vs. Heartworm Cough: How to Tell the Difference
Apr 9, 2025 · Unlike kennel cough, the cough associated with heartworm disease tends to be softer, more chronic, and often worsens with exercise. It's not an ...
[135]
Cat Coughing: Why It Happens and When To Call Your Vet - PetMD
Aug 13, 2025 · Common causes of cat coughing include bronchitis, heartworm, allergies, asthma, and infections. Seek emergency vet care if coughing is ...
[136]
Coughing in Small Animal Patients - PMC - PubMed Central
Jan 21, 2020 · Coughing is frequently reported in dogs with cardiac disease. However, it is not a common clinical sign in cats with cardiac disease. ...Missing: prevalence | Show results with:prevalence
[137]
Evaluating and Managing Chronic Cough in Dogs
For dogs with brachycephalic syndrome, early surgical correction of obstructive airway lesions is advised. Neoplasia. Chronic cough in middle-aged to older dogs ...
[138]
Coughing in Dogs and Cats - WSAVA2009 - VIN
Tracheitis causes a hard but nonproductive cough. The diagnosis is based on the hard, dry cough and the sensitivity of the trachea to palpation, by which the ...
[139]
Kennel Cough in Dogs: Symptoms, Causes, and Treatment - PetMD
Oct 14, 2025 · Kennel cough in dogs is a contagious respiratory condition. Learn about symptoms, treatments, and prevention tips from a veterinarian.Missing: prevalence | Show results with:prevalence
[140]
Kennel Cough - Respiratory System - Merck Veterinary Manual
The disease is often self-limiting, and antibiotics are usually not needed unless there is evidence of pneumonia.
[141]
Heartworm disease | American Veterinary Medical Association
As the disease progresses, your dog may cough, become lethargic, lose his/her appetite or have difficulty breathing. You may notice that your dog seems to tire ...
[142]
Prevalence of canine infectious respiratory pathogens in ...
Jul 21, 2015 · This study determined that a high percentage of asymptomatic shelter dogs harbor CIRD pathogens, including the newly emerging pathogen M. cynos and the ...
[143]
Brachycephalic Airway Syndrome in Dogs | VCA Animal Hospitals
A dog with BOAS must work harder to breathe, causing increased pressure in the airway, which in turn can cause the laryngeal saccules to evert (turn outwards) ...
[144]
Avian influenza | American Veterinary Medical Association
If pet birds become infected, they may be able to spread the virus. Transmission to other animals. Certain mammalian species—including cats and dogs—may become ...
[145]
Transmission of Avian Influenza Virus (H3N2) to Dogs - PMC
Our data provide evidence that dogs may play a role in interspecies transmission and spread of influenza virus.
[146]
The cough reflex in animals: Relevance to human cough research
The cough reflex protects the airways and lungs from airborne and inhaled pathogens, allergens, aspirate and other irritants (figure 1). Humans that have a ...
[147]
Coughing, Mucus Accumulation, Airway Obstruction, and ... - PubMed
In RAO-affected horses, coughing is an indicator of airway inflammation and obstruction. Corticosteroid treatment reduces cough frequency concurrently with ...
[148]
Evolution of lung breathing from a lungless primitive vertebrate - PMC
Oct 21, 2015 · The irritant receptor mediated activity known as “cough” in mammals (Brooks, 2011; Canning, 2008) is a newly derived and distinct reflex ...Missing: comparative | Show results with:comparative
[149]
Respiratory system - Amphibians, Lungs, Gas Exchange | Britannica
The metabolic rate of most reptiles is one-fifth to one-tenth that of birds or mammals, and constant lung ventilation is unnecessary in most reptiles.
[150]
An overview of the sensory receptors regulating cough
Aug 4, 2005 · The cough reflex represents a primary defensive mechanism for airway protection in a variety of mammalian species.
[151]
an aquatic adaptation that risks protection of the respiratory tract in ...
Cetaceans (whales, dolphins, and porpoises) have developed extensive protective barriers to exclude water or food from the respiratory tract, ...Missing: cough reflex
[152]
P2X receptors | Philosophical Transactions of the Royal Society B
Aug 5, 2016 · Extracellular adenosine 5′-triphosphate (ATP) activates cell surface P2X and P2Y receptors. P2X receptors are membrane ion channels ...
[153]
Perspective on the human cough reflex - PMC - PubMed Central - NIH
Nov 10, 2011 · The chemically-sensitive cough reflex was possibly a co-evolutionary response by different animal and plant species and occurred over hundreds ...