A 72-year-old woman developed pruritic erythematous patches on sun-exposed areas for 2 months following treatment with hydrochlorothiazide (Dichlozid) for hypertension. A phototest revealed a decreased minimal erythemal dose to UVA (MED_UVA=2 J/cm²). A photopatch test with 0.5%, 1%, and 5% hydrochlorothiazide ointment revealed no response. Two weeks after discontinuation of hydrochlorothiazide, the skin lesions improved with complete loss of photosensitivity without any therapy. At that time, an oral provocation phototest with hydrochlorothiazide was performed and it showed a decreased MED to UVA (MED_UVA=2 J/cm²).