Diclofenac-Induced Allergic Contact Dermatitis: A Series of Four Patients.

Allergic contact dermatitis is an immune-mediated antigen-specific skin reaction to an allergenic chemical that corresponds to a delayed-type hypersensitivity response (type IV reaction). Allergic contact dermatitis should be suspected when skin lesions are localized to the site of previous applications of the culprit drug. Lesions appear after re-exposure in susceptible persons, with delayed onset (more than 24 h after exposure). The gold standard for diagnosis is patch (epicutaneous) testing; identification and removal of any potential causal agents is crucial. Diclofenac sodium 1% topical gel contains active (diclofenac sodium) and inactive ingredients. It is a widely used non-steroidal anti-inflammatory drug, known to cause allergic contact dermatitis, and especially photoallergic contact reactions. We present four cases of diclofenac-sodium-induced allergic contact dermatitis, diagnosed based on clinical grounds: intensively itchy eczematous lesions on the sites of drug application after several days of treatment. No allergic history and no other drug intake were reported by the patients. The application of diclofenac sodium 1% topical gel was strictly forbidden in all cases; potent topical steroids proved to be effective in all cases within 2 weeks of therapy. Patch tests were performed in all cases with European standard battery, with patients' own diclofenac sodium 1% topical gels and with diclofenac sodium 1% in petrolatum 3 weeks after completion of local steroid therapy. Readings were done after 48 h (Day 2) and 72 h (Day 3) and proved to be positive only to patients' diclofenac sodium 1% topical gel and diclofenac sodium 1% in petrolatum. No sun exposure was allowed during the testing, and any other treatments were forbidden.