Isoniazid intoxication clinically mimicking encephalitis with status epilepticus

Tuberculosis remains an important public health problem even in developed countries. Along with an increasing proportion of tuberculosis cases in migrants from high prevalence countries usage of isoniazid [INH] as a first-line antimicrobial agent for prophylaxis and treatment of tuberculosis is currently rising.

We report a case of a female adolescent who, in a suicidal attempt, ingested a toxic dose of INH (about 50mg per kg body weight). This resulted in encephalitis like symptoms with medically refractory epileptic seiures. Pyridoxine (vitamin B6) at a dose equivalent to the amount of isoniazid ingested eventually lead to rapid and complete resolvment of the neurological symptoms. Mechanisms of acute INH-toxicity and recommendations for the management of acute INH toxicity are reviewed.