Cutaneous photosensitivity to medications.

Photosensitivity induced by exogenous agents accounts for an increasing portion of the total undesirable effects caused by environmental chemicals. The exponential increase in the number of new drugs each year is responsible for a significant rise in the incidence of and disability caused by these reactions. An extensive drug history must be taken whenever a patient presents with a reaction limited to or accentuated in light-exposed areas. These reactions may present with a wide morphologic spectrum ranging from sunburn-like responses to eczematous, lichenoid, and even bullous lesions resembling porphyria cutanea tarda.