Drug-induced photosensitivity (DIP) refers to the development of cutaneous disorders caused by the combined effects of different medications and light. The aim of this study was to obtain new information on drug risk comparisons and on DIP onset profiles, including seasonal variations, for clinically used prescription drugs. We analyzed reports of DIP recorded in the Japanese Adverse Drug Event Report (JADER) database using a reporting odds ratio (ROR). We also used Key words photosensitivity; Japanese Adverse Drug Event Report database; seasonal variation; ketoprofen; hydrochlorothiazide Drug-induced photosensitivity (DIP) refers to the development of cutaneous disorders caused by the combined effects of a variety medications (oral, intravenous, and dermal) and light.1) Although the pathogenesis of DIP reactions is not fully understood, they can be classified as phototoxic or photoallergic drug eruptions.2) The clinical manifestation of phototoxicity is an exaggerated sunburn with blistering, desquamation, and hyperpigmentation, while that of photoallergy is dermatitis.3) Many drugs are associated with photosensitivity. The common photosensitizing medications include antibiotics, antifungals, antihistamines, cholesterol-lowering drugs, diuretics, non-steroidal anti-inflammatory drugs (NSAIDs), oral contraceptives and estrogens, phenothiazines, psoralens, retinoids, sulfonamides, sulfonylureas used for type 2 diabetes, and alpha-hydroxy acids used in cosmetics.