Immediate whealing urticaria in red light exposed areas during photodynamic therapy.

One of the recommended first-line treatments for basal cell carcinomas, actinic keratoses and Bowen's disease is photodynamic therapy. Commonly associated side- effects include pain and phototoxicity. Histamine release is a part of this reaction, but whealing urticaria follow noting photodynamic therapy has only been reported by the manufacturer. The aim of this study was to investigate the prevalence of immediate whealing urticaria in exposed areas during photodynamic therapy with topical methylester aminolevulinate and red light. Patients who developed immediate whealing urticaria during photodynamic therapy were prospectively registered in the period from 1 March 2002 to 14 May 2007. Twelve out of 1353 patients (0.9%) treated with photodynamic therapy developed immediate whealing urticaria and itch during red light illumination, which had not been experienced during previous sessions. Urticaria occurred in 3.8% of patients who had received more than 7 sessions of photodynamic therapy. Prophylactic use of systemic antihistamines reduced itch and whealing, permitting photodynamic therapy sessions to be continued.