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[Immediate hypersensitivity is rarely implicated in drug induced urticaria]
F Cousin1, A Catelain, K Philips
1Unité d'Immunologie Clinique et Allergologie, Centre Hospitalier Lyon Sud, 69495 Pierre-Bénite Cedex.
Annales De Dermatologie Et De Venereologie
|May 15, 2003
Summary
Most drug-induced urticaria cases are pseudo-allergic, not true IgE-mediated allergies. Only 6% of patients showed genuine allergic reactions, often with severe symptoms like anaphylactic shock, while the majority could safely retake the medication.
Area of Science:
- Immunology
- Pharmacology
- Dermatology
Context:
- Drug-induced urticaria presents a diagnostic challenge, differentiating between immediate hypersensitivity and pseudo-allergic reactions.
- Immuno-allergological studies are crucial for evaluating drug intolerance manifesting as urticaria, angioedema, or anaphylaxis.
Purpose:
- To investigate the prevalence of true allergic versus pseudo-allergic urticaria in patients referred for drug intolerance.
- To differentiate IgE-mediated hypersensitivity from pseudo-allergic reactions in drug-induced urticaria.
Summary:
- A prospective study of 350 patients with suspected drug-induced urticaria/angioedema found only 22 (6%) had positive allergy tests for the incriminated drug.
- Genuine allergic reactions, often severe (e.g., anaphylactic shock), were associated with specific drugs like penicillins and cephalosporins.
- The majority of patients (328) exhibited negative tests and could safely resume medication, suggesting pseudo-allergic reactions, often linked to chronic urticaria or dermographism.
Impact:
- This study highlights that most drug-induced urticaria is pseudo-allergic, enabling safe re-administration of medications in the majority of cases.
- Accurate diagnosis differentiates severe allergic reactions from pseudo-allergic responses, guiding appropriate patient management and reducing unnecessary drug avoidance.