Introduction: Intoxication caused by anti-tuberculosis drugs is a rare event in the modern era of medicine. However, high doses of isoniazid may cause convulsion, metabolic acidosis, lactic acidosis, rhabdomyolysis, coma, and eventually death.Case Report: Sixteen-year-old female patient of foreign nationality with no history of systemic disease or drug use was admitted to the emergency department with decreased level of consciousness. Glasgow Coma Scale was 6; pupils were isochoric; and pupillary light reflexes were bilaterally equal. Metabolic acidosis with high anion gap was detected. Following this, a generalized tonic–clonic seizure occurred. These clinical signs and symptoms led to orotracheal intubation. Metabolic acidosis was treated using NaHCO3. After 10 mg of intravenous diazepam injection, the seizure was stopped.However, three additional convulsions occurred and midazolam was intravenously administered. And finally invtravenous pyridoxine (50 mg/kg/day) infusion was started. The patient gained consciousness after 30 minutes.Conclusion: Isoniazid intoxication may be successfully treated with early intervention and the administration of pyridoxine, which is the sole treatment modality