Contents
What Are Salicylates?
Salicylates are a family of naturally occurring phenolic compounds produced by plants as part of their defence systems against pathogens, pests, and environmental stress. The most well-known is salicylic acid, first identified in willow bark and myrtle — and later chemically modified to create acetylsalicylic acid (aspirin), one of the world’s most widely used medicines.
Salicylates exist in two broad forms relevant to human health:
1. Naturally Occurring Dietary Salicylates
Found in many fruits, vegetables, herbs, spices, nuts, teas, and plant-based foods. In the UK, major dietary sources include tomato-based sauces, fruit and fruit juices, wine, tea, and culinary herbs and spices. Concentrations vary widely depending on plant variety, growing conditions, and food processing.
2. Pharmaceutical & Manufactured Salicylates
Aspirin (acetylsalicylic acid) and other NSAIDs that inhibit the COX-1 enzyme; topical salicylates in skin products and cosmetics (salicylic acid in acne preparations, shampoos); methyl salicylate in liniments and muscle rubs; some food preservatives and flavourings (e.g. benzoates, tartrazine azo dyes).
Important distinction: “Salicylate sensitivity” as a popular concept often conflates two clinically distinct phenomena: (1) reactions to dietary salicylates (a poorly characterised pharmacological intolerance), and (2) NSAID/aspirin hypersensitivity (a well-defined clinical syndrome). These have different mechanisms, different diagnostic approaches, and different treatments. A specialist assessment is needed to clarify which is relevant for any individual patient.
Types of Salicylate / NSAID Reaction
Clinicians now recognise several distinct clinical phenotypes of NSAID and salicylate hypersensitivity. These are non-IgE-mediated (not true allergy in the immunological sense) but are recognised hypersensitivity reactions that cause real and sometimes severe symptoms. Understanding which phenotype applies to you is essential for correct management.
AERD / NSAID-ERD
(Aspirin-Exacerbated Respiratory Disease)
The respiratory phenotype. Also known as Samter’s Triad: the combination of chronic rhinosinusitis with nasal polyps, eosinophilic asthma, and respiratory reactions to aspirin and all COX-1 inhibiting NSAIDs. The most clinically significant form, affecting an estimated 10–15% of patients with nasal polyps and/or asthma. Reactions cause bronchoconstriction and/or nasal symptoms within 30–180 minutes of NSAID ingestion.
NECD
(NSAID-Exacerbated Cutaneous Disease)
Worsening of pre-existing chronic spontaneous urticaria (CSU) or angioedema triggered by aspirin or NSAIDs. The patient has underlying CSU and NSAID exposure causes a flare. Dietary salicylates, azo dyes, and benzoate preservatives may also aggravate urticaria in this group.
NIUA
(NSAID-Induced Urticaria / Angioedema)
Urticaria or angioedema in an individual who does not have underlying chronic urticaria. Caused by COX-1 inhibition. These patients often cross-react to multiple NSAIDs. No underlying chronic skin disease is present.
Single-NSAID Hypersensitivity
(Possible IgE-Mediated)
Reactions limited to a single specific NSAID, with other NSAIDs well tolerated. This pattern suggests a true IgE-mediated or T-cell-mediated immunological drug allergy to that particular molecule, rather than a pharmacological COX-1 mechanism. Requires specific drug allergy investigation.
Dietary Salicylate Intolerance
(Food-Derived Pharmacological Intolerance)
A poorly characterised but clinically recognised phenomenon where high dietary salicylate intake appears to aggravate urticaria, rhinitis, or other symptoms in susceptible individuals. Distinct from NSAID hypersensitivity in mechanism — dietary salicylates do not significantly inhibit COX-1. There is no validated diagnostic test; diagnosis relies on supervised elimination and re-challenge.
AERD / Samter’s Triad — The Most Important Salicylate Syndrome
Aspirin-exacerbated respiratory disease (AERD), also known as Samter’s Triad or NSAID-exacerbated respiratory disease (NSAID-ERD), is a chronic inflammatory disease of the upper and lower airways. It is estimated to affect as many as 10–15% of patients with chronic rhinosinusitis with nasal polyps and/or asthma, and may be underdiagnosed in patients presenting with recurrent respiratory or nasal symptoms.
The Classic Triad
1
Asthma
Eosinophilic asthma, often severe and poorly controlled by standard inhalers. Symptoms may precede NSAID sensitivity by months to years.
2
Nasal Polyps
Chronic rhinosinusitis with recurrent nasal polyps, often bilateral and recurring after surgery. Anosmia (loss of sense of smell) is common.
3
NSAID Hypersensitivity
Bronchoconstriction, nasal congestion, rhinorrhoea, and/or facial flushing within 30–180 minutes of taking aspirin or any COX-1 inhibiting NSAID.
AERD typically develops in adulthood, most often between the ages of 30 and 50. The pattern of disease development usually follows a recognisable sequence: rhinitis → chronic eosinophilic sinusitis with polyps → asthma → NSAID sensitivity. Even in the complete absence of NSAID exposure, patients with AERD tend to have more severe asthma and rhinosinusitis than the general asthma and nasal polyp population, reflecting the underlying dysregulated arachidonic acid metabolism that drives the disease.
Clinical alert: Clinicians should maintain a high index of suspicion for AERD in any patient presenting with recurrent nasal polyps, poorly controlled asthma, or a history of respiratory reactions to analgesics. AERD is estimated to be underdiagnosed in 21% of adult asthmatics who have aspirin intolerance that has not been formally investigated.
Symptoms of Salicylate Sensitivity & NSAID Hypersensitivity
Symptoms vary considerably depending on which clinical phenotype is present. They typically develop within 30 minutes to 3 hours of ingesting aspirin, NSAIDs, or (in dietary salicylate intolerance) a high-salicylate meal. Not everyone has the full classical triad.
▲ Respiratory
- Chest tightness or wheezing
- Shortness of breath or cough
- Worsening asthma after NSAID ingestion
- Nasal congestion and rhinorrhoea
▲ Nasal & Sinus
- Chronic nasal congestion
- Recurrent nasal polyps
- Anosmia (loss of smell)
- Recurring sinusitis
▲ Skin
- Urticaria (hives) — acute or chronic
- Angioedema (swelling of lips, eyes, throat)
- Facial flushing
- Worsening eczema in some individuals
▲ Gut & General
- Nausea, abdominal cramps, diarrhoea
- Headache
- Fatigue or brain fog (in dietary intolerance)
- In severe NSAID reactions: anaphylaxis (rare)
Severe reactions: Although anaphylaxis from dietary salicylates is rare, severe NSAID reactions — particularly in AERD patients with poorly controlled asthma — can cause life-threatening bronchospasm. Anyone who has experienced a severe respiratory reaction after taking aspirin or NSAIDs must be assessed by an allergy specialist and should carry appropriate emergency medication.
How Salicylate / NSAID Sensitivity Works
NSAID hypersensitivity in AERD and NECD/NIUA is not IgE-mediated — it does not involve the same immune mechanisms as conventional food or drug allergy. Instead, it is driven by dysregulated arachidonic acid (AA) metabolism:
Normal State
Arachidonic acid is metabolised by COX-1 and COX-2 enzymes to produce prostaglandins — including protective prostaglandin E2 (PGE2), which suppresses mast cells and regulates the leukotriene pathway.
In AERD / NSAID Hypersensitivity
COX-1 is constitutionally overexpressed and PGE2 levels are already low at baseline. When aspirin or NSAIDs inhibit COX-1, the residual PGE2 brake is removed, triggering a sudden surge in pro-inflammatory cysteinyl leukotrienes (CysLTs) — causing bronchoconstriction, nasal congestion, and urticaria.
This explains why all COX-1 inhibiting NSAIDs — ibuprofen, naproxen, diclofenac, aspirin, and many others — trigger reactions in AERD patients, even those they have never taken before. The mechanism is pharmacological and class-wide, not specific to a single drug molecule.
Dietary salicylates, by contrast, do not significantly inhibit COX-1 at doses obtainable from food. Their role in aggravating conditions such as chronic urticaria is therefore likely to involve different, less well-characterised mechanisms — possibly related to non-COX pharmacological activity or direct mast cell effects.
Diagnosis of Salicylate & NSAID Hypersensitivity
There is no validated blood test or skin prick test for NSAID hypersensitivity or dietary salicylate intolerance. Diagnosis is primarily clinical, supported by a structured specialist assessment. The gold standard for NSAID-ERD / AERD is a supervised oral aspirin provocation challenge in an appropriately equipped specialist setting.
Step 1: Detailed Clinical History
Nature and timing of all previous NSAID reactions; symptom phenotype (respiratory, cutaneous, or both); presence of asthma, nasal polyps, or chronic urticaria; prior surgical history for nasal polyps; all current medications. This is the most important diagnostic step.
Step 2: Baseline Investigations
Spirometry and reversibility testing (for asthma assessment); CT or nasal endoscopy (for nasal polyp evaluation); blood eosinophil count and IgE; serum tryptase; urinary leukotriene E4 (LTE4) — elevated in AERD even at baseline and useful as a diagnostic marker.
Step 3: Supervised Aspirin Challenge
Gold standard for AERD diagnosis. A graded oral aspirin challenge is performed in clinic with spirometry monitoring and full resuscitation facilities. Graduated aspirin doses are administered at intervals; a fall in FEV1 of ≥15–20% or the development of nasal or respiratory symptoms confirms diagnosis. Requires stable asthma before challenge.
Dietary Salicylate Intolerance
No validated objective test exists. Diagnosis relies on a supervised elimination diet (removing high-salicylate foods for 4–6 weeks) followed by structured food reintroduction, with symptom monitoring. Conducted under the guidance of the allergy consultant and a specialist dietitian.
Before any aspirin challenge: The challenge must not be performed in patients with poorly controlled or unstable asthma (FEV1 <70% predicted), or during an active urticaria flare. Your consultant will assess your clinical stability at a pre-challenge appointment.
Treatment of NSAID Hypersensitivity & AERD
Management of AERD has evolved substantially with the availability of respiratory biologic therapies. Current treatment is multidisciplinary, involving allergy, respiratory medicine, and ENT, and is tailored to phenotype and severity.
NSAID Avoidance
The cornerstone of immediate management. Patients must avoid aspirin and all COX-1-inhibiting NSAIDs (ibuprofen, naproxen, diclofenac, ketorolac, indomethacin, etc.). However, avoidance alone does not control the underlying disease — asthma and nasal polyps persist regardless of NSAID exposure.
Standard Asthma & Rhinosinusitis Management
Inhaled corticosteroids (ICS) and long-acting beta-agonists (LABA) for asthma; intranasal corticosteroids and saline irrigation for rhinosinusitis. Leukotriene receptor antagonists (e.g. montelukast) may provide additional benefit by targeting the CysLT pathway that is central to AERD pathogenesis.
Aspirin Desensitisation
A structured protocol in which aspirin is given in gradually increasing doses in clinic until tolerance is established, followed by daily high-dose aspirin maintenance. Effective for improving both upper and lower respiratory symptoms in motivated patients. Conducted as an inpatient or closely monitored outpatient procedure. Not suitable for patients with aspirin-induced urticaria without underlying chronic urticaria, or those with unstable cardiac disease.
Surgical Management
Functional endoscopic sinus surgery (FESS) for severe or recurrent nasal polyps. In AERD, polyps frequently recur after surgery, making adjunctive medical therapy — including biologics — important for sustained disease control. Our ENT consultants work collaboratively with our allergy team for combined care.
Low-Salicylate Diet — Guidance & Food Lists
Important caveat: A low-salicylate diet is primarily relevant for patients with dietary salicylate intolerance aggravating urticaria or other symptoms, and as an adjunct in some AERD patients. It should be supervised by an allergy consultant and specialist dietitian — not undertaken on the basis of unvalidated test results. Unnecessary restriction of fruits and vegetables carries nutritional risks.
A prospective crossover study (Sommer et al.) found that a 6-week low-salicylate diet in AERD patients produced measurable improvement in both subjective symptom scores and objective endoscopic findings. The effect was modest and should be considered an adjunct rather than a primary treatment. Salicylate content varies considerably by food preparation and cooking method.
Note: Salicylate content of individual foods varies widely depending on variety, ripeness, and cooking method. Cooked and peeled fruits and vegetables generally contain less salicylate than raw. This table provides general guidance only — individual thresholds vary and a personalised plan from a specialist dietitian is strongly recommended. Some sufferers can tolerate small amounts of high-salicylate foods without reaction.
Safe Analgesic Alternatives for Salicylate-Sensitive Patients
Choosing analgesics safely is one of the most important practical challenges for patients with NSAID hypersensitivity. The following guidance is general — your consultant will advise on your specific situation after formal assessment.
✓ Paracetamol (Acetaminophen)
First-line recommended analgesic for salicylate-sensitive patients at standard therapeutic doses (up to 1 g four times daily). Does not inhibit COX-1 at standard doses. Generally well tolerated in AERD, NECD, and NIUA. Use with caution at higher doses in patients with known sensitivity to paracetamol at low doses (rare).
◆ COX-2 Selective NSAIDs
Celecoxib and etoricoxib (COX-2 selective inhibitors) may be tolerated by many NSAID-hypersensitive patients because they spare COX-1 at therapeutic doses. However, they must only be used after formal specialist assessment and supervised provocation testing — they are not automatically safe for all phenotypes. Some AERD patients still react to selective COX-2 inhibitors.
✗ Avoid Without Assessment
All standard NSAIDs — including aspirin, ibuprofen (Nurofen), naproxen, diclofenac, indomethacin, ketorolac, and mefenamic acid — should be avoided until a formal diagnosis and risk assessment is performed. Many over-the-counter cold and flu remedies contain aspirin or ibuprofen — always read the label.
Topical salicylates: Muscle rubs and skin preparations containing methyl salicylate (e.g. Deep Heat) may also cause reactions in sensitive individuals, particularly when applied over large body surface areas. Aspirin and salicylate-containing cosmetics (acne treatments, some shampoos) should similarly be reviewed with your consultant.
Biologic Therapies for AERD & Urticaria — 2025 Updates
The management of AERD and NSAID-related urticaria has been transformed by the availability of targeted biologic therapies. These are now central to the management of patients who fail conventional treatment, and are reshaping the question of whether aspirin desensitisation remains the preferred approach in the era of biologics.
Dupilumab (Dupixent®)
Anti-IL-4Rα monoclonal antibody
Licensed for severe eosinophilic asthma, chronic rhinosinusitis with nasal polyps (CRSwNP), and — as of April 2025 — FDA-approved for chronic spontaneous urticaria (CSU) in patients aged 12 and older uncontrolled on antihistamines. This marks the first new targeted CSU therapy in over a decade. MHRA consideration for the UK is anticipated. Dupilumab targets the IL-4/IL-13 pathway central to type-2 eosinophilic inflammation in AERD and CRSwNP, and has shown substantial benefits for nasal polyp reduction and asthma control.
Reference: FDA approval April 2025; LIBERTY-CSU CUPID Phase 3 trials.
Omalizumab (Xolair®)
Anti-IgE monoclonal antibody
MHRA-licensed for severe allergic asthma, chronic spontaneous urticaria (first-line biologic for CSU in the UK), and as adjunct therapy in chronic rhinosinusitis with nasal polyps. In AERD patients with CSU (NSAID-exacerbated cutaneous disease), omalizumab is the preferred first-line biologic. It substantially reduces urticaria activity and may increase the safety of aspirin desensitisation in selected patients.
Available privately at our clinic. MHRA-licensed in the UK for CSU and allergic asthma.
Mepolizumab / Benralizumab
Anti-IL-5 / Anti-IL-5Rα biologics
Licensed for severe eosinophilic asthma and, in the case of mepolizumab, for CRSwNP. In AERD patients with significant blood eosinophilia and severe asthma, these biologics can substantially reduce asthma exacerbations, steroid requirements, and nasal polyp burden. Suitability assessed by the allergy consultant based on eosinophil count, IgE level, and clinical phenotype.
MHRA-licensed for eligible patients. Discuss at your consultation.
Biologics or aspirin desensitisation? This is now a key clinical decision in AERD management. A 2025 paper in Allergy highlights that biologics and aspirin desensitisation are not mutually exclusive — both approaches have a role, and some patients benefit from combined therapy. The choice depends on disease phenotype, severity, concomitant conditions, and patient preference. Your consultant will discuss the evidence and options fully at your appointment.
Frequently Asked Questions
Important Notice
This page provides general educational information only and is not a substitute for personalised medical advice. Do not stop prescribed medication or undertake dietary elimination without first consulting your doctor. In a medical emergency, call 999.
References
- Elahi S, Peters AT, Kato A, Stevens WW. Clinical and mechanistic advancements in aspirin exacerbated respiratory disease. J Allergy Clin Immunol. 2025;155(5):1411–1419. doi:10.1016/j.jaci.2025.03.006
- Szatkowski W, et al. What is the next step for patients with AERD: biologics with or without aspirin therapy? Allergy. 2025. doi:10.1111/all.16462
- Sanofi / Regeneron. Dupixent (dupilumab) FDA approval for chronic spontaneous urticaria in patients aged 12 and older. April 2025. LIBERTY-CSU CUPID Phase 3 trial data.
- Foerster U, et al. Importance of aspirin challenges in patients with NSAID-exacerbated respiratory disease. HNO. 2024;72(7):494–498. doi:10.1007/s00106-024-01460-9
- Sommer DD, et al. Dietary modification for AERD: a prospective crossover study. Low salicylate diet in patients with AERD. Published in Int Forum Allergy Rhinol.
- Swain AR, Soutter VL, Loblay RH. Food and Chemical Intolerance: A Clinical Guide. Allergy Unit, Royal Prince Alfred Hospital. Regularly updated.
- Magerl M, et al. EAACI/GA²LEN/EDF/WAO Guideline for the Definition, Classification, Diagnosis and Management of Urticaria. Allergy. 2022;77(3):734–766.
- National Institute for Health and Care Excellence (NICE). Anaphylaxis: Assessment and Referral after Emergency Treatment. CG134. 2011 (reviewed 2020).
Page reviewed: June 2026 | London Allergy and Immunology Centre | privateallergy.uk