When your child had that first fever, the thought of a seizure might have crossed your mind. A seizure triggered by a sudden fever is somewhat common, affecting about 2 percent to 4 percent of children younger than age 5. These fever-induced seizures, called febrile seizures, usually don’t signal a long-term or ongoing problem, but a doctor should evaluate your child.
The result of an abnormal electrical impulse in the brain, a seizure typically involves muscle spasms or convulsions, loss of consciousness, eyes rolled to the back of head, loss of urine and vomiting. Simple febrile seizures, the most common, last from a few seconds to 15 minutes. Afterward, your child may cry or be very sleepy.
A rapid fever spike to about 102°F, such as those caused by a middle-ear infection or the viral illness roseola, can prompt a simple febrile seizure. A tendency for febrile seizures may run in some families. Although rare, a seizure can be a side effect of an immunization, caused by the resulting fever, not the vaccination.
Other conditions that trigger seizures include metabolic disturbances from kidney or liver disease; low levels of blood sugar, sodium, calcium or magnesium; a previous head injury; birth defects; the use of drugs or other chemicals; poisoning; or a brain tumor.
Watching your child have a seizure is frightening, but it is important to stay calm. Move your child to a safe area on the floor, gently roll him or her onto one side and remove any nearby objects. Loosen clothing around the head or neck but do not place anything in the mouth or try to restrain movements. Time the seizure—seizures seem to last longer than they actually do—and report its length to your doctor. Call for emergency medical care if your child has:
- a first or different type of seizure
- difficulty breathing
- ingested poison or medication
- a seizure that lasts more than five minutes
- two or more seizures
Simple febrile seizures don’t cause brain damage or learning disabilities, but one-third of children will have another seizure with a subsequent fever. First febrile seizures usually occur between ages 6 months and 3 years, and most children outgrow them by 5 or 6 years old. Your child’s doctor may conduct blood tests as well as an electroencephalogram (EEG), magnetic resonance imaging (MRI) or a computerized tomography (CT) scan to study the brain and rule out other causes.