Fixed-Drug Eruption due to Dextromethorphan

To the Editor.—  Fixed-drug eruption (FDE) is a common cutaneous reaction caused by a variety of drugs.^1-2 In many cases, the causative agent is confirmed by the patient's history; however, in some uncertain cases, oral challenge² or topical testing³ is useful.Dextromethorphan (dextromethorphan hydrobromide; D-3-methoxymorphinan) acts centrally by elevating the threshold for coughing. It is widely used, both alone and in combination with other compounds. As far as we know, no FDE or other skin reactions to dextromethorphan have been reported.

Report of a Case.—  Since 1985, a healthy 45-year-old woman had been using antitussive drugs containing dextromethorphan (Extuson and Resilar) for two or three periods of 2 to 3 weeks a year. In March 1989, after taking dextromethorphan (Extuson [30 mg]) she developed an erythematous patch, 3 cm in diameter, on her right upper arm. In the center of the patch there was a blister, 2