Thiazide diuretic therapy and chronic photosensitivity.

Chronic photosensitivity associated with hydrochlorothiazide ingestion occurred in four patients. These patients developed a debilitating photosensitivity that persisted for months to years even after they stopped taking the diuretic. Their age range was 44 to 66 years. Phototesting with ultraviolet B (UV-B) and ultraviolet A (UV-A) radiation revealed decreased minimal erythemal doses for one or both wave bands in all patients tested. Histologic examination of skin biopsy specimens from the patients' UV-B and UV-A test sites and lesional skin revealed an acute eczematous dermatitis. Treatment with methoxsalen and UV-A radiation successfully cleared the photosensitive eruption in the patients.