Photosensitivity reaction to methenamine hippurate. A case report.

We describe a 70-year-old woman who in the summer of 1992 presented at our department with an erythematous and blistering rash on the sun-exposed areas of her face, trunk and upper limbs. She had been taking methenamine hippurate for several years to prevent urinary tract infections after an cystopexia operation. Oral photoprovocation with the drug revealed an immediate reaction after 3 J of ultraviolet A not seen before oral photoprovocation.