Drug-induced photosensitivity (DIP) is a cutaneous adverse event caused by the combined effects of a medication and exposure to light. The article by Nakao et al. evaluated the association between drugs and DIP by using the reporting odds ratio and time-to-onset analysis data from the Japanese Adverse Drug Event Report (JADER) database. More than half of the reports of DIP onset following ketoprofen administration were recorded within 10 days of initiation of treatment. The seasonal variation of DIP was shown to follow an annual sinusoidal pattern with peaks observed in April and May. The results of this study suggest close monitoring of patients taking suspected drugs, especially during the peak season of photosensitivity reactions.