Fever is also one of the most common causes of seizures, affecting approximately 4% of all children, typically between 6 months and 5 years. Known as febrile seizures, parents will find these convulsions frightening though they are usually harmless. The infections that lead to these seizures are almost always caused by viruses and often mild ones at that. The seizures themselves are usually caused by a rapid increase in body temperature in the early stage of an infection, which can take place before the parents have even realized that their child has a fever.

Febrile seizures typically last a few seconds up to a minute, but can go on for as long as 15 minutes. During this time, the child may begin to look strange, then stiffen, twitch, and roll his eyes. He may also be unresponsive for a short time, and his skin may appear darker than usual. During the seizure, move your child, if necessary, to a safe place like the floor or bed, and away from any sharp objects. Turn his head to the side so that any saliva or vomit can drain.  Do not put anything in his mouth. Once the seizure is over, report it promptly to your pediatrician; go to the emergency room if it was prolonged (15 minutes or more) or your child is having trouble breathing afterwards.

Febrile seizures tend to run in families. If a baby has a febrile seizure before he turns 1, he has about a 50 percent chance of experiencing another such episode. A child who has a febrile seizure after age 1 has about a 30 percent chance of having another. Still, almost all kids outgrow febrile seizures by age 6.