Fever seizures (sometimes called fever convulsions) are uncontrolled muscle spasms that can occur in children who have a rapid increase in body temperature. You may not even know your child has a fever. The rapid increase in body temperature in a short period of time is the cause of the fever seizure. Once a fever has reached a high temperature, the risk of a seizure is probably over. Most children who have a fever seizure have temperatures above 102F.

Fever seizures can be frightening but they are not usually harmful to the child and do not cause long-term problems, such as brain damage, mental retardation, or learning problems.

Fever seizures affect 2% to 4% of children. About 30% of children who have a fever seizure will have another one, usually within a year of the first seizure. These seizures are not a form of epilepsy.

A child who is having a seizure often loses consciousness and shakes, moving his or her arms and legs on both sides of the body. The child's eyes may roll back. The child may stop breathing for a few seconds and might also vomit, urinate, or pass stools. It is important to protect the child from injury during a seizure.

Fever seizures usually last 1 to 3 minutes. After the seizure, the child may be sleepy. You can let the child sleep, but check the child frequently for changes in color or breathing, or twitching arms or legs. The child also may seem confused after the seizure, but normal behavior and activity level should return within 60 minutes of the seizure.

A seizure is more likely to have been caused by a fever if the seizure occurred within 24 hours of the start of a fever. Fever seizures usually affect the whole body, not just one side. Most children have never had a fever seizure before and they also do not have other nervous system (neurologic) problems.

Review the Emergencies and Check Your Symptoms sections to determine if and when your child needs to see a health professional.