Drug-induced photoallergic and phototoxic reactions.

1New York Medical College, Department of Dermatology, Metropolitan Hospital Center, New York, NY 10029, USA, 2Columbia University, Department of Dermatology, Columbia University Medical Center, New York, NY 10032, USA Scheinfeld@earthlink.net.

Drug-induced photosensitivity involves reactions to medication triggered by exposure of the skin to ultraviolet light. Medications that trigger reactions can be topical or oral. Following interaction of ultraviolet radiation with a chemical present in sufficient amounts in the skin, one of the several reactions may occur in susceptible patients, most commonly photoallergy or phototoxicity. These reactions can be diagnosed separately based on pathogenesis, clinical characteristics and histopathology. Phototoxic disorders have a higher incidence than photoallergic disorders. The action spectra for most photoallergens and phototoxins lie in the ultraviolet A range. Subtypes of drug-induced photosensitivity include dyschromia, pseudoporphyria, photo onycholysis, and lichenoid and telangiectatic reactions.