Febrile seizures are convulsions or seizures in infants or small children that are brought on by a fever or febrile illness. The seizures may come before the fever. Most often during a febrile seizure, a child loses consciousness and shakes uncontrollably. 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 may last for more than 15 minutes. Approximately one in every 25 children will have at least one febrile seizure. Febrile seizures usually occur in children between the ages of 6 months and 5 years, with the risk peaking in the second year of life. The older a child is when the first febrile seizure occurs, the less likely that child is to have more febrile seizures as they will spend less time in the age group at risk.
A few factors appear to boost a child’s risk of having recurrent febrile seizures, including a family history of febrile seizures in a first- or second-degree relative, a young age (less than 18 months) at the first febrile seizure, having a lower peak temperature during the illness when the febrile seizure occurs, and the febrile seizure occurring within an hour of recognized fever.
The vast majority of febrile seizures are short and harmless. There is no evidence that short febrile seizures cause brain damage. Multiple or prolonged seizures are a risk factor for epilepsy but most children who experience febrile seizures do not go on to develop the reoccurring seizures that are characteristic of epilepsy. Certain children who have febrile seizures face an increased risk of developing epilepsy. These children include those who have a febrile seizure that lasts longer than 10 minutes that affects only one part of the body, or febrile seizures that re-occur within 24 hours.
At particularly high risk for future epilepsy are those with a history of very prolonged (more than 30 minutes) febrile seizures which can cause injury to a part of the brain called the hippocampus.
A child who has a febrile seizure usually doesn’t need to be hospitalized unless the seizure is prolonged or is accompanied by a serious infection. Preventive treatment involving daily use of anti-seizure medicines is not recommended because of their potential for harmful side effects. Children especially prone to febrile seizures may be treated with medication when they have a fever to lower the risk of having another febrile seizure but this lowers the risk only slightly and does not affect long-term prognosis.
For those with a history of prolonged febrile seizures, medications which terminate the seizure can be used at home at time of a seizure.