Phytophotodermatitis due to the application of citrus hystrix as a folk remedy.

We report a case of extensive phytophotodermatitis in a hiker. This was caused by the application of the juice of a member of the Rutaceae family, Citrus hystrix, as a folk remedy to ward off biting insects. Besides the Rutaceae, plants belonging to the families Umbelliferae, Moraceae and Leguminosae also contain psoralens and can cause phytophotodermatitis. In temperate countries, cases are often seen among children playing outdoors during summer, when psoralens are most abundant in wild and garden plants.