Donepezil: an unusual therapy for acute diphenhydramine overdose.

An elderly man presented with the history of diphenhydramine hydrochloride overdose as a suicidal attempt. At presentation, he was in an acute confusional state with several anticholinergic features and had to be managed in intensive care unit. As an antidote for diphenhydramine hydrochloride, donepezil was used instead of physostigmine due to the unavailability of physostigmine in Bangladesh. The patient improved within the next 24 hours; his level of consciousness improved and the anticholinergic features regressed.