Photoallergic reaction to cyamemazine.

A 50-year-old man presented with a scaly erythema of the face, upper chest, forearms, and dorsum of the hands. He has been treated with cyamemazine for 6 months. Photopatch tests were performed and the patient was diagnosed with photoallergic reaction to cyamemazine. The drug was discontinued and a course of oral steroids was prescribed. The patient was advised to avoid light exposure. There has been no evidence of recurrence during a six-month follow-up period. Photoallergic reactions are much less frequent than phototoxic disorders. It is well known that several drugs including neuroleptics of the phenothiazine family may produce a skin eruption on light-exposed areas by dose-dependent (phototoxic) or photoallergic mechanisms. It is believed that photopatch testing, which is the clinical investigation of choice for suspected photoallergic reactions, is significantly underused in Europe and probably world-wide.