A 44-year-old male presented to the emergency department with altered mental status. He was receiving niacin therapy for hypercholesterolemia, and 16 hours earlier had ingested a large quantity of wine. Past medical history was otherwise unremarkable; physical examination revealed paranoid ideation and asterixis. Laboratory evaluation was significant for metabolic acidosis with a calculated anion gap of 39. Liver enzymes were elevated, and lactic acid level was 9.5 mmol/L (normal: 0.5 to 2.2 mmol/L). White blood cell count was 23,100, but all cultures were negative, and all other diagnostic studies, including bilirubin, prothrombin time, and ammonia were normal. The patient recovered rapidly with hydration and administration of thiamine and magnesium. After psychiatric evaluation, a diagnosis of toxic delirium due to niacin and ethanol coingestion was made. This is the first case reporting toxic delirium and lactic acidosis due to niacin and ethanol coingestion. This occurred in the absence of significant hepatic impairment. Possible mechanisms for the observed derangements are discussed.