Aspirin-exacerbated respiratory disease

Lore & Background

AERD affects an estimated 0.3–0.9% of the general population in the US, including around 7% of all asthmatics, about 14% of adults with severe asthma, and ~5-10% of patients with adult onset asthma. It is uncommon among children, with around 2-3% of patients, predominantly female, reporting disease onset during childhood. The disorder typically progresses from rhinitis to asthma, then nasal polyposis, with aspirin sensitivity coming last. Hyposmia or anosmia are reported in more than 90% of patients. Reactions to NSAIDs range in severity and expression, with onset usually within one hour after ingestion. Respiratory reactions are essentially universal, with bronchoconstriction occurring in approximately 80-85% of patients and nasal congestion and rhinorrhea in more than 40%.

Reader's Guide

The cause of AERD is a dysregulation of the arachidonic acid metabolic pathway and of various innate immune cells, though the initial cause is unknown. This dysregulation leads to an imbalance of immune related molecules, including overproduction of inflammatory compounds such as leukotriene E4 and underproduction of anti-inflammatory mediators such as prostaglandin E2. A history of respiratory reactions to aspirin or other NSAIDs is sufficient to diagnose AERD in a patient that has both asthma and nasal polyps. As there is no cure, treatment revolves around managing symptoms with corticosteroids, surgery, diet modifications, monoclonal antibody-based drugs, and paradoxically, daily aspirin therapy after desensitization. AERD is not considered an autoimmune disease but a chronic immune dysregulation, classified by EAACI/WHO as one of five types of NSAID hypersensitivity.

Did You Know?

• More than 90% of AERD patients experience reduction or loss of the ability to smell.
• AERD is more prevalent among women by up to a 2:1 margin.
• Reactions to NSAIDs in AERD are hypersensitivity reactions, not allergic reactions.
• Selective COX-2 inhibitor NSAIDs such as celecoxib are generally regarded as safe, though caution is recommended.

The Triad and the People It Claims

AERD is defined by the simultaneous presence of three conditions: persistent asthma, chronic rhinosinusitis accompanied by nasal polyps, and a documented intolerance to aspirin and related nonsteroidal anti-inflammatory drugs. Patients living with this triad tend to experience noticeably more severe asthma and polyp growth than those with asthma who tolerate aspirin without issue. A striking feature is the near-universal impact on the sense of smell; over ninety percent of affected individuals report either a diminished or completely lost ability to smell, likely because the chronic inflammation within the nasal cavity and sinuses extends to the olfactory receptors. The disease most frequently declares itself during the twenties through the forties, with an average onset around age thirty-five. It is uncommon in childhood, affecting roughly six percent of pediatric cases, and those who do develop it early are predominantly female. Among the general U.S. population, an estimated 0.3 to 0.9 percent will encounter AERD, though the proportion climbs to about seven percent among all asthmatics and as high as fourteen percent among those with severe adult asthma. Women are affected at up to twice the rate of men. The condition has been documented across essentially every ethnicity, though it appears less frequently in certain parts of Asia where type 2 inflammatory nasal polyps are rarer. Crucially, there is no known cure, and simply avoiding NSAIDs does not alter the disease's onset, trajectory, or lifelong course.

The Immune Machinery Gone Awry

At its core, AERD stems from a breakdown in two interlocking systems: the arachidonic acid metabolic cascade and the regulation of innate immune cells. The exact trigger that sets this dysregulation in motion remains unknown. Hypotheses have pointed to a superantigen from Staphylococcus aureus, persistent viral infections, or autoimmune mechanisms, yet none has been confirmed with sufficient evidence. No strong genetic predisposition has been identified, and familial clustering of the disease is rare. Importantly, prior use of NSAIDs does not appear to cause the condition. The metabolic disruption produces a dangerous tilt in the balance of immune-related molecules. Inflammatory compounds such as leukotriene E4 are overproduced, while anti-inflammatory mediators like prostaglandin E2 are underproduced. Reduced PGE2, in turn, fails to adequately suppress the enzyme 5-lipoxygenase, further amplifying leukotriene generation. These two pathological components—metabolic and immunological—feed into one another in a self-reinforcing cycle of escalating inflammation. The net effect is persistent, chronic inflammation of the respiratory tract. AERD is classified not as an autoimmune disorder but as a chronic immune dysregulation, and the EAACI/WHO framework places it among five recognized types of NSAID hypersensitivity.

A Diagnostic Puzzle That Unfolds Over Time

Diagnosing AERD is deceptively difficult in its early stages because the hallmark symptoms rarely arrive together. The most common first sign is rhinitis—sneezing, a runny nose, or congestion—which can easily be mistaken for ordinary allergic or nonallergic rhinitis. Asthma typically follows, and nasal polyposis develops next, with aspirin sensitivity often appearing last. Until all three elements of the triad are present, clinicians may label the patient with adult-onset asthma or chronic sinusitis alone, delaying a correct diagnosis. Once the full picture emerges, however, the diagnostic criteria become straightforward: a documented history of respiratory reactions to aspirin or other NSAIDs, combined with both asthma and nasal polyps, is sufficient to confirm AERD. It is worth emphasizing that the reactions triggered by NSAIDs in these patients are hypersensitivity responses, not classic IgE-mediated allergic reactions of the kind that produce hives or allergen-driven asthma. The symptoms are respiratory in nature and stem from the underlying immune dysregulation rather than from a traditional allergy mechanism. This distinction matters both for patient understanding and for guiding appropriate management strategies.

Managing a Disease Without a Cure

Because no cure exists, clinical management of AERD centers on keeping the three symptom clusters under control. Standard tools include corticosteroids, surgical intervention for polyps, dietary adjustments, and newer monoclonal antibody therapies targeting specific inflammatory pathways. One of the most counterintuitive strategies is daily aspirin desensitization: after a carefully supervised initial challenge, many patients can take low-dose aspirin every day, which paradoxically helps reduce symptoms rather than provoke them. When a patient does react to an NSAID, the response is almost always respiratory and can be life-threatening. The mean onset is roughly one hour after ingestion, though reactions as late as three hours have been recorded. Bronchoconstriction occurs in close to ninety percent of reactions, while nasal congestion and rhinorrhea appear in over forty percent. Additional manifestations include hives, facial flushing, angioedema, and drops in blood pressure. Severity is influenced by the NSAID dose, how well the patient's asthma is controlled, whether leukotriene modifiers are in use, and the current state of the nasal polyps. Selective COX-2 inhibitors and low-dose acetaminophen are generally considered safer alternatives, though recent evidence urges caution with any COX-inhibiting medication. Even small amounts of alcohol can provoke uncomfortable respiratory episodes in many patients.