Toxic dose
A toxic dose has not been clearly defined for tiagabine. Doses above 100 mg can cause toxicity in adults, with documented survival at doses up to 1500 mg.
Drug-naive children who have ingested more than 1 mg/kg of tiagabine require medical assessment and observation (see Potential toxic doses of some antiepileptic drugs in drug-naive children for potential toxic doses of some antiepileptic drugs in drug-naive children). Small doses of tiagabine can provoke seizures in children who are naive to this drug. Doses as low as 8 mg of tiagabine in a child have been associated with drowsiness, and full recovery has been reported in a child who ingested 90 mg.