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Systemic contact dermatitis to hydroxyzine
1Northwestern University, School of Medicine, Evanston, IL, USA.
Summary
Systemic contact dermatitis, an allergic reaction to oral medications, can cause chronic eczema. Identifying and removing the trigger, like hydroxyzine, often resolves the condition.
Area of Science:
- Dermatology
- Allergy and Immunology
Background:
- Systemic contact dermatitis (SCD) is a delayed hypersensitivity reaction to systemically administered substances.
- Oral medications can cross-react with topical antigens, triggering SCD.
- Chronic, unresponsive eczema may indicate an underlying systemic cause.
Observation:
- A patient presented with eczema unresponsive to treatment.
- Patch testing revealed a positive reaction to ethylenediamine.
- The patient had a history of taking hydroxyzine for pruritus.
Findings:
- Repeated oral provocation with hydroxyzine successfully reproduced the patient's eczema.
- This confirmed hydroxyzine as the causative agent for systemic contact dermatitis.
- Ethylenediamine is a common metabolite or impurity in hydroxyzine.
Implications:
- Systemic contact dermatitis to hydroxyzine should be considered in cases of chronic, recalcitrant eczema.
- Thorough medication history, including oral drugs, is crucial for diagnosing SCD.
- Identifying and eliminating the offending agent can lead to significant clinical improvement.