COMA FROM LONG-TERM OVERINGESTION OF ISONIAZID

Overingestion of isoniazid can cause confusion, slurred speech, seizur es, coma, and death. Most cases of a central nervous system toxic reac tion due to isoniazid use result fi-am sudden intentional or accidenta l overdose. We describe a patient taking 1200 mg of isoniazid daily fo r 6 weeks who presented to the hospital with confusion and lethargy th at progressed to coma. Within 30 minutes of receiving 1 g of intraveno us pyridoxine hydrochloride, the patient was fully alert and lucid. Th e diagnosis of a toxic reaction to isoniazid was delayed by the possib ility of concurrent active neurosyphilis and the failure to initially consider isoniazid poisoning in a patient without a history of sudden isoniazid overdose.