Febrile seizures occur in 3 to 5 percent of children ages 6 months to 6 years, making them the most common known cause of seizures. A febrile seizure is a seizure that is provoked by fever above 100 degrees Fahrenheit. A febrile seizure, or even several febrile seizures, does not usually point to epilepsy. This is because these seizures are not spontaneous, and most children outgrow them by age 6. A febrile seizure is a very frightening experience for parents, partly because the fever may not be recognized until after the seizure occurs. In addition, the seizure often takes the form of a convulsion. Still, febrile seizures are usually harmless, unless the child is injured during the seizure. In fact, two studies of children with febrile seizures showed that the intellectual development of the children was the same as their siblings who did not have seizures. Following a first febrile seizure, a child should be evaluated right away to rule out infectious meningitis and other serious causes of seizures and fever. Meningitis can be ruled out by a spinal tap, or even with clinical observation. Febrile seizures do have a tendency to run in a family. For example, the younger sibling of a child with febrile seizures is three times more likely than normal to experience the condition. Even so, most febrile seizures occur with no family history of seizures. After one febrile seizure, about half of children will have another one sometime in their life, but this doesn't necessarily lead to epilepsy. Several studies have examined the risk for later epilepsy among children with febrile seizures, and found it to be in the range of 2 to 4 percent. This means that about 10 to 20 percent of people with epilepsy have previously had a febrile seizure. Certain complicating factors, though, can increase the risk for later epilepsy after a febrile seizure. Among them are: febrile seizures longer than 15 minutes, febrile seizures in one focal part of the body, multiple febrile seizures within 24 hours; or a family history of non-febrile seizures. It is difficult to notice or treat a rising fever before a febrile seizure occurs. Daily antiepileptic medications might prevent febrile seizures...but there is no good evidence that trying to prevent this condition with antiepileptic medicines reduces the risk that a person will develop epilepsy. This is an important issue, since seizure medications can impair a child's learning and personality. For example, phenobarbital, which is the usual medication used to prevent febrile seizures, can produce hyperactivity and behavioral and learning problems in a significant percentage of children. For these reasons, most pediatric neurologists believe that treatment of febrile seizures is worse than the risk of having one, and advise no therapy. Remember, while 3 to 5 percent of children will experience febrile seizures, they are only a very slight risk marker for later epilepsy, as over 95 percent of the children with febrile seizures will not develop epilepsy!