[Delirium in a 73-year-old man after many years of unwise use of betahistine].

A 73-year-old man was admitted because of delirium that had already persisted for 5 days. The physical examination and extensive tests did not reveal any somatic pathology. The only drug he used was betahistine, taken for several years because of supposed Ménière's disease. After withdrawal of betahistine and treatment with haloperidol the patient recovered completely within a few days. A new delirium was induced when, after discharge from the hospital, betahistine was restarted because of dizziness. There was again a complete remission after betahistine was stopped and haloperidol was restarted. Betahistine is not known to induce delirium, but an investigation in side-effects databases did reveal several cases in which delirium might have been present, even though the term was not actually used. In this case, delirium was possibly caused by the combination of an elevated betahistine plasma level and a damaged blood-brain barrier due to cerebral infarctions, which were revealed by CT and MRI.