Febrile convulsions occur in 3.4 percent of children but are rarely a harbinger of epilepsy. However, children who have two or more uncomplicated, noncomplex or "simple" febrile convulsions should receive anticonvulsant therapy. Phenobarbital is recommended for children who have a single febrile convulsion that is unilateral or focal and lasts more than 15 minutes. It is also recommended for cases involving multiple convulsions in one day, a physical or neurologic abnormality or a subnormal or suboptimal developmental history.