Adverse reaction to mefloquine associated with ethanol ingestion

A 40-year-old man with no history of neuropsychiatric illness was taking one 250-mg tablet of mefloquine (MFQ) weekly for malaria prophylaxis while in Tanzania. He experienced no adverse reaction in association with his first two doses. Concurrently with both his third and his fourth dose he consumed about half a litre of whisky. On both occasions he experienced hallucinations, paranoid delusions and suicidal ideation. Thereafter he continued taking the MFQ, abstained completely from ethanol ingestion and had no recurrence of psychiatric symptoms. It is hypothesized that the combination of MFQ and ethanol caused the two episodes of severe psychiatric disturbance.