RESUMO
Isoniazid is an anti-tuberculosis drug, used commonly for treatment and prophylaxis of tuberculosis. Acute isoniazid intoxication is characterized by a clinical triad consisting of metabolic acidosis resistant to treatment with sodium bicarbonate, seizures which may be fatal and refractory to standard anticonvulsant therapy, and coma. Treatment requires admission to the intensive care unit for ventilatory support, management of seizures and metabolic acidosis. Pyridoxine, in a dose equivalent to the amount of isoniazid ingested, is the only effective antidote. We report the successful treatment of two isoniazid intoxication cases: the case of a child developing an accidental acute isoniazid intoxication and an adult case of isoniazid intoxication with the intent of suicide.