Carbamazepine toxicity related to clarithromycin administration in an elderly patient: a case report

Acute vestibular syndrome is a known adverse effect of carbamazepine toxicity. Plasma levels increase to toxic concentrations when combined with drugs that alter its metabolism. Pediatric and elderly populations are particularly vulnerable due to their susceptibility and polypharmacy. We present the case of a 75-year-old woman with a history of primary epilepsy treated with carbamazepine who presented to the emergency department with acute vertigo. She reported taking clarithromycin for an upper respiratory tract infection in the past 48 hours. Laboratory tests revealed supratherapeutic carbamazepine levels (>20 mg/L), and neuroimaging findings were normal. Symptoms are resolved progressively within 24 hours of antibiotic discontinuation. This case highlights the importance of recognizing drug interactions in polymedicated patients. The relevance of clinical suspicion, monitoring, and physician education in preventing and detecting iatrogenesis is discussed.