Idiosyncratic reactions to phenytoin.

We present a detailed case report of an idiosyncratic reaction to phenytoin and review the manifestations in 16 additional pediatric patients (2.5-21 years of age) described in the literature. These cases illustrate the frequency of fever (82%), rash (94%), lymphadenopathy (94%), hepatitis (94%), and eosinophilia (76%). This constellation of signs and symptoms will frequently mimic common pediatric illnesses so the pediatrician responsible for the care of the seizure patient being treated with phenytoin should be aware of the possibility of an idiosyncratic reaction. Delay in discontinuation of the drug may be life-threatening.