ABSTRACT
Reactions caused by photosensitivity, also called photodermatosis, are cutaneous reactions induced or exacerbated by exposure to electromagnetic radiation, including UV radiation, visible light, and infrared radiation. We present the case of a 41-year-old man with no personal history of allergy and who is referred to our Drug Allergy Unit for study. We performed a conventional patch test (non-irradiated) and photopatch (with the application of UVA) with reading at 48 and 96 hours and 24 hours after irradiation with an intensity of 5J/cm2. Drug-induced photosensitivity can manifest itself in two clinically indistinguishable forms: photoallergy and phototoxicity. Photoallergic reactions are due to an immunological response of type IV hypersensitivity (a cell-mediated mechanism). We present a case of photoallergy due to sensitization to naproxen, confirmed by photopatch tests.
