Toxic dose
A dose of more than 20 mg/kg phenytoin can cause cerebellar toxicity (ataxia, dysarthria, nystagmus). A dose of more than 100 mg/kg phenytoin can cause sedation and possibly coma.
Drug-naive children who have ingested more than 20 mg/kg of phenytoin 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).