Phenytoin toxicity: an easily missed cause of cerebellar syndrome

We present a series of cases of phenytoin toxicity where the diagnosis was initially missed. These patients all suffered unnecessary morbidity or investigations. The side-effects and unusual pharmacokinetics of phenytoin are discussed, as well as the array of potential drug interactions. We remind clinicians that phenytoin toxicity can easily mimic a cerebellar lesion or alcohol intoxication, and suggest that in accordance with National Institute for Clinical Excellence (NICE) guidelines phenytoin should no longer be used as a first-line treatment for epilepsy.