Febrile seizures are convulsions brought on by a fever in infants or small children. During a febrile seizure, a child often loses consciousness and shakes. Less commonly, a child becomes rigid or has twitches in only a portion of the body. Most febrile seizures last a minute or two; some can be as brief as a few seconds, while others last for more than 15 minutes. Febrile seizures usually occur in children between the ages of 6 months and 5 years and are particularly common in toddlers. A few factors appear to boost a child's risk of having recurrent febrile seizures, including young age (less than 15 months) during the first seizures, frequent fevers, and having immediate family members with a history of febrile seizures.

A child who has a febrile seizure usually doesn't need to be hospitalized. If the seizure is prolonged or is accompanied by a serious infection, or if the source of the infection cannot be determined, a doctor may recommend that the child be hospitalized for observation. Prolonged daily use of oral anticonvulsants, such as phenobarbital or valproate, to prevent febrile seizures is usually not recommended because of their potential for side effects and questionable effectiveness for preventing such seizures.

The vast majority of febrile seizures are harmless. There is no evidence that febrile seizures cause brain damage. Certain children who have febrile seizures face an increased risk of developing epilepsy. These children include those who have febrile seizures that are lengthy or that recur within 24 hours and who have cerebral palsy, delayed development, or other neurological abnormalities.

Prepared by the National Institutes of Health