Hypersensitivity reactions with antiepileptic drugs (AEDs) are generally associated with aromatic AEDs. We present a case of hypersensitivity reactions followed by administration of phenytoin with diazepam and ranitidine in a patient with generalized tonicâclonic seizures. Antigenâantibody reactions or decreased levels of epoxide hydrolase are well known with phenytoin. Increased level of serum phenytoin causing toxicities due to competitive inhibition with diazepam on coâadministration was also reported in the literature. Prevention of the adverse effects with AEDs is a multiâstage process, which requires implementation of preventive measures through careful monitoring and prompts interventions.