Distigmine bromide is an anticholinesterase used to treat urinary retention. We describe a case of decreased serum cholinesterase caused by a usual oral dose of distigmine bromide for urinary retention. An 84-year-old man, who had been received chemotherapy for carcinoma of the lower gingiva, suddenly decreased serum cholinesterase to 21 IU/L in 7 days of administration of distigmine bromide 5mg without clinical symptoms. Serum cholinesterase improved after stopping the administration of distigmine bromide. This case shows that oral surgeons should be aware of the possibility of decreased serum cholinesterase in patients taking distigmine bromide.
