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Salicylate sensitivity

Salicylate sensitivity, also known as salicylate intolerance, is a non-immunological adverse to salicylates—naturally occurring chemicals found in many fruits, , spices, and , as well as synthetic compounds in medications like aspirin—characterized by pseudo-allergic responses rather than true IgE-mediated allergies. This condition arises from the inhibition of enzymes, leading to disrupted metabolism and the overproduction of pro-inflammatory leukotrienes, which triggers symptoms in susceptible individuals. It is estimated to affect 0.3–2.5% of the general population, with prevalence up to 7–20% among adults with (as of the 2020s). Symptoms primarily affect the respiratory, dermatological, and gastrointestinal systems and often overlap with (AERD), or Samter's triad (, nasal polyps, and aspirin sensitivity). Diagnosis involves clinical and provocation tests, while management emphasizes avoidance of salicylates, though dietary interventions have limited and debated efficacy; for AERD, aspirin desensitization is a key therapy.

Definition and Terminology

Definition

Salicylate sensitivity, also referred to as salicylate intolerance, is defined as a non-immunological adverse reaction to normal therapeutic or dietary amounts of salicylates, resulting in symptoms such as respiratory, cutaneous, or gastrointestinal disturbances. Unlike true allergies, which involve IgE-mediated immune responses, salicylate sensitivity operates through pseudo-allergic or pharmacological pathways, often linked to altered metabolism. It is also distinct from salicylism, the syndrome caused by excessive doses of salicylates like aspirin, which affects individuals regardless of predisposition and leads to severe systemic effects such as , , and . Salicylates are chemical compounds derived from , a naturally occurring substance found in various , including the bark of willow trees (Salix species), where it serves as a defense mechanism against pathogens. In modern contexts, salicylates appear in high concentrations in everyday foods such as fruits (e.g., berries, apples), vegetables (e.g., , tomatoes), spices (e.g., , ), and herbs, as well as in synthetic forms within medications (e.g., aspirin and other nonsteroidal anti-inflammatory drugs), food preservatives, and like perfumes and treatments. This sensitivity typically manifests as a pseudo-allergic response, where exposure triggers the release of inflammatory mediators like leukotrienes due to inhibition of enzymes, mimicking allergic symptoms without involving antigen-specific immunity.

Terminology and Classification

Salicylate sensitivity, also referred to interchangeably as salicylate intolerance or aspirin sensitivity, describes a non-immunological adverse reaction to salicylates, compounds found in certain medications like aspirin and in various foods. This condition is distinct from aspirin , which involves IgE-mediated immunological mechanisms, and from salicylism, a form of toxicity resulting from acute overdose of salicylates leading to symptoms such as , , and . Instead, salicylate sensitivity arises from pharmacological effects, primarily the inhibition of cyclooxygenase-1 (COX-1) enzymes, disrupting metabolism and balance without involvement. The classification of salicylate sensitivity encompasses several subtypes based on predominant clinical manifestations, often cross-reactive with other nonsteroidal anti-inflammatory drugs (NSAIDs) that inhibit COX-1. One major subtype is (AERD), characterized by the triad of , chronic with nasal polyps, and to aspirin or other COX-1 inhibitors, also known as Samter's triad. Another subtype involves cutaneous reactions, such as urticaria or , where exposure triggers hive-like rashes or swelling through increased production. A third subtype manifests as gastrointestinal intolerance, featuring symptoms like diarrhea or chronic inflammation due to altered synthesis in the gut. Historically, the terminology for these reactions evolved from early descriptions as "pseudo-allergy" or "pseudoimmunopathy" in the mid-, reflecting their mimicry of allergic responses without immunological basis, to more precise terms like "pharmacological intolerance" by the late , emphasizing the drug's direct biochemical effects. This shift, prominent by the 1970s in , aligned with growing understanding of inhibition pathways and distinguished these reactions from true hypersensitivities. Salicylate sensitivity falls within the broader category of non-allergic reactions, where pharmacological or metabolic disruptions cause symptoms resembling allergies, and it overlaps with intolerances, as dietary salicylates from sources like fruits and spices can provoke similar responses through the same imbalances.

Pathophysiology and Etiology

Pathophysiological Mechanisms

Salicylate sensitivity primarily arises from the inhibition of (COX-1 and COX-2) enzymes by salicylates, such as aspirin, which disrupts the metabolic pathway. This inhibition reduces the synthesis of protective prostaglandins, particularly (PGE2), leading to a metabolic shunt of toward the 5-lipoxygenase (5-LO) pathway and subsequent overproduction of cysteinyl leukotrienes (CysLTs). The elevated CysLTs, including leukotriene C4 (LTC4) and D4 (LTD4), play a central role in the inflammatory response characteristic of salicylate sensitivity, particularly in (AERD). These mediators promote , , and mucosal by binding to CysLT1 and CysLT2 receptors on airway cells, , and mast cells. In sensitive individuals, baseline overproduction of CysLTs is further amplified by salicylate exposure, exacerbating inflammatory cascades. Mast cell activation contributes significantly to the pseudo-allergic response in salicylate , occurring independently of IgE-mediated mechanisms. Salicylates trigger the release of , , and additional CysLTs from s and , amplifying without involving classical allergic pathways. Genetic factors, such as polymorphisms in leukotriene pathway genes including LTC4S (−444A>C), ALOX5, and CYSLTR1/CYSLTR2, predispose individuals to heightened CysLT production and receptor , influencing disease susceptibility. Differences in salicylate underlie the accumulation of these compounds in sensitive individuals, leading to prolonged and intensified pseudo-allergic reactions. Impaired detoxification pathways result in altered profiles, with elevated levels of pro-inflammatory metabolites like 15-hydroxyeicosatetraenoic acid (15-HETE) and eoxins, compared to non-sensitive populations. This metabolic dysregulation sustains the inflammatory imbalance triggered by inhibition.

Causes and Risk Factors

Salicylate sensitivity arises from a combination of genetic predispositions and environmental exposures that impair the body's ability to tolerate salicylates, compounds found in certain medications and foods. Genetic factors play a significant role, with variants in genes involved in metabolism, such as polymorphisms in the 5-lipoxygenase gene (ALOX5) and C4 synthase gene (LTC4S), increasing susceptibility to salicylate-induced reactions, particularly in (AERD). Additionally, variants in the gene (FLG), which affects epithelial barrier integrity, have been identified in approximately 5% of AERD patients, contributing to heightened through compromised and mucosal barriers. Other genetic associations include polymorphisms in HLA-DPB1, which may influence immune responses to salicylates. Environmental exposures represent primary non-genetic causes, primarily through ingestion of salicylates from dietary sources like fruits, , spices, and teas, as well as medications such as aspirin and other nonsteroidal drugs (NSAIDs). Cumulative exposure from diets rich in salicylate-containing plant-based foods—such as currants (up to 66 mg/kg) or (up to 2 mg/g)—can exacerbate sensitivity in predisposed individuals by overwhelming metabolic pathways. Key risk factors include coexisting atopic and inflammatory conditions that amplify salicylate intolerance. AERD, a subtype of salicylate sensitivity, occurs in 2-25% of asthmatic adults, with higher rates (up to 9%) in those with severe asthma. It is strongly linked to chronic rhinosinusitis with nasal polyps, where nearly all AERD cases feature this comorbidity, driven by shared eosinophilic inflammation. Atopic dermatitis increases risk, with meta-analyses indicating salicylate intolerance in up to 53% of affected individuals (95% CI 44-62%). Inflammatory bowel disease (IBD) patients face elevated risks due to intolerance to aminosalicylate therapies like mesalamine, which can worsen disease control and necessitate alternative treatments. Frequent NSAID use heightens risk by mimicking salicylate effects on pathways. Non-genetic triggers such as infectious agents can precipitate sensitivity in at-risk individuals by temporarily disrupting immune .

Clinical Presentation

Symptoms and Signs

Salicylate sensitivity manifests through a range of observable symptoms primarily affecting the respiratory, dermatological, and gastrointestinal systems, with additional effects possible in other areas. These signs typically arise following exposure to salicylates in foods, medications, or environmental sources, and their severity can vary among individuals. Respiratory symptoms are among the most common, particularly in individuals with (AERD), where they form a core component of the condition. These include , , , sneezing, runny or stuffy nose, coughing, wheezing, chest tightness, and exacerbation of leading to . In AERD, such reactions often occur in a significant proportion of cases, with reported in 5–10% and bronchial in 10% of affected patients. Dermatological signs present as skin reactions such as (urticaria), (Quincke's edema), flushing, itching, redness, or rashes, which may flare in sensitive individuals. These manifestations affect approximately 20–30% of cases and can appear as if exposure persists. Gastrointestinal effects encompass , , , , , gas, , or chronic intestinal irritation such as . These symptoms occur in 2-7% of reported cases and may contribute to ongoing discomfort with repeated exposure. Other symptoms can include headaches and, in some instances, tinnitus (ringing in the ears), though these are more commonly associated with higher-dose exposures. In children, behavioral changes such as hyperactivity have been anecdotally reported but remain controversial with limited supporting evidence. Fatigue may also occur as a general sign. Symptoms generally onset within minutes to one hour after exposure and can last for hours, resolving upon removal of the trigger, though chronic signs like nasal polyps may persist or recur.

Associated Conditions

Salicylate sensitivity is strongly associated with aspirin-exacerbated respiratory disease (AERD), also known as Samter's triad, which comprises asthma, chronic rhinosinusitis with nasal polyps, and hypersensitivity to aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs). AERD affects approximately 7-10% of adult patients with asthma, with higher rates observed in those with severe asthma or nasal polyposis. In individuals with salicylate sensitivity, exposure can exacerbate respiratory symptoms and contribute to the persistence of nasal polyps, which often prove refractory to standard treatments without dietary salicylate avoidance. Elevated rates of salicylate sensitivity are also noted in chronic urticaria, where aspirin and NSAIDs can induce or worsen cutaneous symptoms in up to 20% of affected patients. Gastrointestinal disorders show notable links, including (IBS) and (IBD), with dietary salicylates implicated in symptom induction in a subset of cases; for instance, sensitivity occurs in up to 7% of patients with . Other comorbidities include , where recent meta-analyses indicate salicylate intolerance in up to 53% of individuals, potentially triggering flares. Migraines are frequently exacerbated by salicylate exposure in sensitive individuals, with dietary triggers like certain fruits and herbs contributing to onset. Salicylate sensitivity also overlaps with (MCAS), where altered metabolism leads to predominance and heightened responses upon exposure. These associations often exhibit bidirectional influences, wherein salicylate sensitivity can intensify underlying conditions—such as worsening nasal polyposis or urticarial flares—while the presence of comorbidities like AERD or MCAS may amplify susceptibility to salicylates. In rare cases, particularly among children, high-salicylate diets have been linked to behavioral issues resembling ADHD symptoms, including hyperactivity and irritability, though evidence remains limited to observational reports.

Diagnosis and Assessment

Clinical Evaluation and History

The clinical evaluation of suspected salicylate sensitivity begins with a comprehensive patient history to establish potential links between exposures and symptom onset, as this non-invasive approach is foundational for guiding further assessment. A detailed dietary history is essential, focusing on consumption of high-salicylate foods such as berries, spices like (containing up to 2180 mg/kg), and fruits like (23 mg/kg), alongside medications including aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs). Clinicians correlate these exposures with reported symptoms, such as respiratory distress or gastrointestinal upset, noting the timing—often immediate or within hours—to differentiate patterns suggestive of intolerance. Patients are routinely advised to maintain a symptom for 2-4 weeks, logging daily intake of potential triggers and any ensuing reactions to identify consistent patterns. This tool helps quantify exposure-response relationships, such as worsening after spice consumption, and supports the exclusion of unrelated factors by documenting variability in symptom severity. During physical examination, clinicians look for indicative signs including nasal polyps (present in up to 30% of cases), wheezing indicative of , and skin manifestations like rashes or urticaria, which may appear during acute episodes. These findings, often confirmed via nasal revealing bilateral polyps or detecting wheezing, provide objective correlates to the history. Inquiry into family history plays a role in assessing genetic predisposition, with approximately 6% of affected individuals reporting familial aspirin hypersensitivity, suggesting heritable factors in arachidonic acid metabolism. To exclude confounders like true IgE-mediated allergies, evaluation emphasizes the absence of antigen-antibody responses; salicylate sensitivity manifests as a pseudoallergic reaction driven by eicosanoid imbalances rather than immunoglobulin E involvement.

Diagnostic Tests and Challenges

Diagnosing salicylate sensitivity relies primarily on provocative testing methods, as no definitive biomarkers exist. The gold standard for confirming dietary salicylate intolerance involves an elimination diet trial, typically following the Royal Prince Alfred Hospital (RPAH) protocol, which restricts high-salicylate foods, amines, and additives for 2-6 weeks to achieve symptom stabilization before controlled reintroduction to provoke reactions. During reintroduction, incremental challenges with salicylate-containing foods (e.g., starting with low doses like pears or golden delicious apples) are monitored for recurrence of symptoms such as , gastrointestinal distress, or respiratory issues, confirming sensitivity if reactions align with prior patterns. For (AERD), a subtype of salicylate sensitivity, an oral aspirin challenge serves as a confirmatory test in a supervised clinical setting. This involves incremental dosing starting at 20-40 mg, escalating to 325 mg over 1-2 days while monitoring forced expiratory volume in 1 second (FEV1) for drops exceeding 20%, alongside symptoms like or ; nasal or bronchial provocation variants may be used for patients unable to tolerate . Challenges require baseline FEV1 ≥70% predicted and are performed under specialist oversight with rescue medications (e.g., albuterol) available. No reliable biomarkers, such as specific tests, exist for salicylate sensitivity, limiting objective to clinical provocation. Urinary leukotriene levels may elevate post-challenge in AERD cases but lack diagnostic specificity and are not routinely used. Diagnostic challenges include the risk of severe anaphylactoid reactions during challenges, necessitating specialist facilities and contraindications like unstable or pregnancy. False negatives can occur in mild or intermittent cases due to variable symptom expression, while the absence of biomarkers complicates verification without provocation. Differential diagnosis requires ruling out overlapping sensitivities, such as to sulfites (common in wines and preservatives, provoking at doses as low as 4.6 mg in highly sensitive individuals) or (a yellow dye triggering similar reactions at 3.4 mg thresholds), through targeted exclusion or separate challenges. These distinctions are critical, as salicylate reactions involve inhibition and overproduction, unlike the direct pseudoallergic mechanisms of sulfites or tartrazine.

Management and Treatment

Dietary Interventions

The primary dietary intervention for managing salicylate sensitivity involves adopting a low-salicylate diet, which restricts intake of foods high in naturally occurring salicylates while permitting those with negligible or low levels. This approach is based on quantitative assessments of salicylate content in over 300 food items, revealing high concentrations in certain fruits like oranges (approximately 2.39 mg/100 g), berries such as raspberries (5.14 mg/100 g), and nuts including almonds (3.0 mg/100 g), as well as beverages like (4.78 mg/100 mL) and spices such as (218 mg/100 g). In contrast, allowable foods include pears (0.27 mg/100 g with skin), (negligible at 0.39 mg/kg), , , and (all 0 mg/100 g), enabling a balanced intake without complete elimination of plant-based foods. The , introduced in the 1970s, provides a structured protocol originally aimed at reducing hyperactivity but applicable to salicylate sensitivity by eliminating salicylates alongside artificial flavors, colors, and preservatives. This diet categorizes foods into phases, starting with strict avoidance of high-salicylate items and progressing to reintroduction for tolerance testing. Modified versions, such as the Failsafe Diet developed by the Royal Prince Alfred Hospital, extend this by also limiting amines and flavor enhancers while emphasizing "safe" low-salicylate options like white potatoes and to support long-term adherence. Practical implementation requires careful meal planning, such as preparing simple dishes with permitted staples like plain meats, eggs, and low-salicylate grains, while scrutinizing labels for hidden sources including mint flavorings in gums or herbal teas and curry spices in prepared sauces. Supplementation may be necessary to address potential gaps, using low-salicylate forms like ascorbic acid for or plain multivitamins without fruit-derived additives. The diet typically begins with a strict elimination phase lasting 4-6 weeks, followed by gradual reintroduction and ongoing monitoring of symptoms through food diaries to identify personal thresholds. Clinical studies indicate that adherence to a personalized low-salicylate can reduce symptom severity in sensitive individuals, with one trial reporting significant improvements in , , and urticaria for 73% of participants after 2-4 weeks. However, challenges include maintaining nutritional balance due to restricted fruits and , which may lead to deficiencies in vitamins and fiber if not managed with substitutes like or supplementation, as well as social difficulties from dining out or family meals. Long-term compliance demands professional guidance from dietitians to mitigate these risks and ensure .

Pharmacological and Other Therapies

Leukotriene modifiers, including and , are commonly prescribed to inhibit the overproduction of , which play a central role in the inflammatory response of salicylate sensitivity, especially in (AERD). These receptor antagonists reduce , improve control, and attenuate reactions to aspirin exposure by blocking cysteinyl leukotriene pathways. Clinical studies indicate they are effective in managing symptoms for a substantial portion of AERD patients, with demonstrating reductions in upper airway symptoms during aspirin challenges. Zafirlukast similarly contributes to symptom relief, though evidence is more limited compared to . For pain management in patients with salicylate sensitivity, alternatives to traditional nonsteroidal anti-inflammatory drugs (NSAIDs) are essential to avoid exacerbations. Selective (COX-2) inhibitors like celecoxib are generally safer in AERD, as they exhibit minimal with aspirin and do not typically provoke respiratory symptoms. However, caution is advised due to potential variability in individual responses, and celecoxib should be used at the lowest effective dose. Acetaminophen serves as a first-line option for mild to moderate pain, with most AERD patients tolerating doses up to 500 mg without adverse effects. Aspirin desensitization protocols represent a for AERD-associated salicylate sensitivity, involving supervised gradual escalation of aspirin doses to induce . Standard protocols administer escalating doses over hours to days, culminating in of 325–650 mg twice daily, which stabilizes upper and lower respiratory symptoms in the majority of patients. This approach achieves long-term in approximately 80% of cases, reducing burden and exacerbations while improving . Desensitization is performed in specialized centers with for reactions, often preceded by modifier pretreatment. Adjunctive therapies address specific manifestations of salicylate sensitivity beyond core . Antihistamines, such as or loratadine, are effective for controlling urticaria and triggered by salicylates, providing symptomatic relief by blocking histamine-mediated responses. In refractory AERD with persistent nasal s, biologics like , an interleukin-4 and interleukin-13 inhibitor, serve as an adjunct to or standard care, significantly reducing polyp size and improving outcomes. has demonstrated rapid efficacy in AERD cohorts, preventing polyp recurrence post-endoscopic . Emerging pharmacological options include 5-lipoxygenase inhibitors like zileuton, which directly suppress synthesis upstream of receptor antagonists, offering additive benefits in AERD symptom control and potentially reducing the need for sinus surgeries. Preliminary research explores modulation as a novel adjunct, investigating how gut or sinonasal microbial alterations might influence inflammatory pathways in salicylate-sensitive conditions, though clinical applications remain investigational.

Epidemiology

Prevalence and Incidence

Salicylate sensitivity affects an estimated 1-2.5% of the general worldwide, with data primarily derived from European studies indicating up to 2.5% in that region. This rate is higher in specific at-risk groups, such as those with , where incidence ranges from 2-22%, and in (AERD), affecting 5-20% of asthmatics depending on diagnostic methods like oral provocation testing. Up to 20-40% of patients with chronic urticaria may experience exacerbations from salicylates or related non-steroidal anti-inflammatory drugs. Recent analyses highlight elevated rates in other conditions: a 2025 meta-analysis reported a pooled of 53% for salicylate intolerance among individuals with , based on low-certainty evidence from clinical trials. In (IBS), is estimated at 2-7%, while 15-20% of patients with chronic rhinitis or nasal polyps show sensitivity, often linked to pseudo-allergic reactions. These figures underscore the condition's association with inflammatory and allergic disorders, though exact incidence varies by diagnostic criteria. Salicylate sensitivity is likely underdiagnosed due to the absence of standardized tests, relying instead on tests or elimination diets that are not routinely performed. Incidence appears stable over time, but recognition has increased since the through expanded research on food chemicals and intolerance mechanisms. Reports are more frequent in developed countries, potentially attributable to diets rich in processed foods containing added salicylates and greater clinical awareness.

Demographic and Geographic Patterns

Salicylate sensitivity exhibits distinct patterns across groups and es, with the majority of cases manifesting in adulthood. The condition peaks between 30 and 50 years of , as evidenced by mean ages around 46 years in cohorts with related respiratory symptoms like chronic rhinosinusitis with nasal polyps. Pediatric cases, though less common, are frequently associated with behavioral symptoms such as hyperactivity, , and inappropriate , often prompting elimination diets for . Regarding , overall reports indicate a slight male predominance in certain populations, such as in , where affected individuals are marginally more likely to be men. However, in (AERD), a subset of salicylate sensitivity, females comprise the majority, often comprising 68% or more of diagnosed cases. Geographic and ethnic variations highlight higher recognition of salicylate sensitivity in Western populations, particularly in and , where dietary exposures to salicylate-rich are more commonly implicated in symptoms. In contrast, reports from Asian regions, such as , appear lower, potentially attributable to dietary differences with reduced intake of high-salicylate or underdiagnosis due to differing clinical on other pseudoallergens. Ethnic patterns are less well-documented, but variations in food production and cultural diets influence exposure levels, with plant-based salicylates more prominent in regions favoring fruits, vegetables, and spices. Socioeconomic factors contribute to observed disparities, with higher rates in settings linked to greater of processed foods that may contain added salicylates or related compounds. Access to low-salicylate diets is uneven, as maintaining such restrictions can be challenging for lower-income groups due to limited availability of suitable foods and nutritional guidance. Comorbidity patterns underscore elevated salicylate sensitivity among atopics, where up to 53% of individuals with experience flares linked to salicylate intake, often manifesting as food-induced rashes. In (IBD) cohorts, overlap occurs in approximately 2-7% of cases, complicating symptom management in those with gastrointestinal hypersensitivity. Recent data from the 2020s indicate rising awareness, particularly in (MCAS) patients, where salicylates are increasingly recognized as triggers exacerbating multisystem symptoms.

Historical Development

Early Discoveries

The use of bark, a natural source of salicylates, dates back thousands of years in various ancient cultures for alleviating pain and inflammation. In , around 1550 BCE, the documented willow leaves as a remedy for treating inflammatory conditions and wounds. Similarly, clay tablets from approximately 4000 years ago referenced willow for pain relief. In , , often regarded as the father of medicine, prescribed willow bark tea around 400 BCE to ease childbirth pains and reduce fever in women. Native American tribes also employed willow bark infusions for centuries to treat headaches, fever, and rheumatic pains, recognizing its properties through traditional herbal practices. Advances in the marked the scientific isolation of salicylate compounds from willow bark. In 1828, German pharmacologist Johann Andreas Buchner successfully extracted a bitter, crystalline substance from willow bark, naming it after the Latin term for willow, Salix. This glucoside was further refined by French pharmacist Henri Leroux in 1829, who isolated it in purer form for potential therapeutic use. Building on this, Italian chemist Raffaele Piria, working in , hydrolyzed in 1838 to yield , a more potent acidic derivative responsible for the bark's effects. These isolations laid the groundwork for understanding salicylates' pharmacological potential, though early applications were limited by the compounds' irritancy to the stomach. The development of aspirin represented a pivotal refinement in salicylate utilization. In 1897, German chemist at Laboratories synthesized acetylsalicylic acid by acetylating with , creating a more stable and tolerable form that reduced gastric side effects. This compound was patented and marketed by in 1899 as Aspirin, rapidly gaining popularity as an over-the-counter and . Early observations of adverse reactions to salicylates emerged shortly after aspirin's introduction. In 1902, German physician Viktor G. S. Hirschberg reported the first documented case of an idiosyncratic hypersensitivity reaction, describing acute urticaria and occurring within hours of aspirin ingestion in a . Such reports, termed "idiosyncratic" at the time, highlighted rare but severe cutaneous responses, prompting initial medical caution regarding individual variability in salicylate tolerance.

Modern Recognition and Research

In the early 20th century, respiratory reactions to aspirin were first described. In 1922, physicians Maurice Widal, P. Abrami, and J. Lermoyez reported cases of severe asthma exacerbations in patients with and nasal polyps following aspirin intake, marking an initial recognition of respiratory hypersensitivity. However, these observations remained sporadic until the mid-20th century. In the 1960s and 1970s, salicylate sensitivity gained recognition primarily through its association with aspirin intolerance in patients with and nasal polyps. Early clinical observations linked aspirin ingestion to acute respiratory exacerbations in asthmatics, with a 1967 study by Samter and Beers characterizing the condition as a distinct triad involving , nasal polyposis, and to aspirin, now known as Samter's triad. Subsequent research in 1975 by Szczeklik et al. demonstrated that aspirin-induced attacks resulted from inhibition of biosynthesis, establishing the reaction as non-allergic in nature and involving altered metabolism rather than IgE-mediated mechanisms. This period marked a shift from viewing the sensitivity as idiosyncratic to understanding it as a pseudoallergic response driven by biochemical imbalances. The 1980s brought advancements in quantifying dietary salicylates and exploring their role beyond pharmaceuticals. Anne Swain and colleagues published a seminal 1985 analysis measuring salicylate levels in 333 food items using , revealing high concentrations in fruits (e.g., berries and dried fruits), herbs (e.g., and ), and beverages like , while cereals, meats, and showed negligible amounts. This work facilitated the development of low-salicylate diets. Concurrently, the , initially proposed in the 1970s for hyperactivity, gained popularity in the 1980s by eliminating salicylates alongside artificial additives, though subsequent reviews highlighted its controversial efficacy, with limited evidence supporting salicylate elimination as a primary intervention for behavioral disorders. During the 1990s and , the condition was more precisely defined, and mechanistic insights deepened. In 1999, Szczeklik's review formalized (AERD) as the clinical triad of , chronic with nasal polyps, and respiratory reactions to COX-1 inhibitors like aspirin. Building on this, Szczeklik's research in the elucidated the COX inhibition pathway, showing that aspirin selectively blocks COX-1, reducing protective prostaglandins (e.g., PGE₂) and shunting toward overproduction of pro-inflammatory cysteinyl leukotrienes via the 5-lipoxygenase pathway, with urinary LTE₄ levels elevated 2- to 10-fold in affected patients. A 2009 review further outlined the , emphasizing dysregulation and pseudoallergic activation of inflammatory cells without immunological specificity. From the to 2025, research expanded into , standardization, and broader intolerances. Genetic studies polymorphisms in leukotriene-related genes, such as LTC₄ and CYSLTR2, increasing AERD and FEV₁ decline post-aspirin , with a 2016 highlighting thromboxane A₂ receptor variants as risk factors. Desensitization protocols were standardized in the , evolving to efficient one-day regimens (e.g., 90-minute oral escalations starting at 40.5 mg aspirin) that safely induce tolerance in stable AERD patients with FEV₁ ≥70%, reducing burden and use. A 2025 meta-analysis of four studies (n=188) reported a 53% of salicylate intolerance in flares (95% CI: 44–62%), providing low-certainty evidence of atopic links and calling for refined dietary s. Ongoing microbiome research post-2020 explores gut in food chemical intolerances, including salicylates, with cohort studies linking microbial profiles to symptom persistence, though causal mechanisms remain under investigation. Increased focus on food intolerances since 2020 has integrated these findings into nutritional concerns, emphasizing non-immune reactions in chronic conditions.

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