<prompt> Male with erythematous patch over penis after taking an over the counter medicine. Causal drug is:AzithromycinOfloxacinDoxycyclineAceclofenac  <response>: Ans. D. AceclofenacRef: Fitzpatricks Color Atlas and Synopsis of Clinical Dermatology, 7thed p498-99Explanation Findings given in question are suggestive of fixed drug eruptions FDE. Among the given options ofloxacin, doxycycline and azithromycin are prescription only drugs hence most probably the answer is aceclofenac. If in question over the counter has not been mentioned then the answer will be doxycycline. A FDE is an adverse cutaneous reaction to an ingested drug, characterized by the formation of a solitary but at times multiple erythematous patch or plaque. If the patient is rechallenged with the offending drug, the FDE occurs repeatedly at the identical skin site i.e., fixed within hours of ingestion. Usually asymptomatic. May be pruritic, painful, or burning. Time to onset oflesions: Occur from 30 min to 8 h after ingestion of drug in previously sensitized individual. Duration oflesions: Lesions persist if drug is continued. Resolve days to few weeks after drug is discontinued. Tetracyclines tetracycline, doxycycline, minocycline Sulfonamides, other sulfa drugs Metronidazole, nystatin, salicylates, NSAIDs, phenylbutazone, phenacetin Barbiturates Oral contraceptives Quinine including quinine in tonic water, quinidine Phenolphthalein Food coloring yellow: in food or medications 