Febrile seizures
Seizure - fever induced; Febrile convulsions
A febrile seizure is a convulsion in a child triggered by a fever.
A febrile seizure is a generalized tonic-clonic (grand mal) seizure that occurs in some children as a response to a fever. Febrile seizures are usually associated with rapidly rising fevers, and usually occur early in the fever rather than later.
The central nervous system comprises the brain and spinal cord. The peripheral nervous system includes all peripheral nerves.
Causes
A temperature of 100.4°F (38°C) or above may cause febrile seizures in children.
A febrile seizure can be frightening for any parent or caregiver. Most of the time, a febrile seizure does not cause any harm. The child usually does not have a more serious long-term health problem.
Febrile seizures occur most often in otherwise healthy children between ages 6 months and 5 years. Toddlers are most commonly affected. Febrile seizures often run in families.
Most febrile seizures occur in the first 24 hours of an illness. It may not occur when the fever is highest. A cold or viral illness may trigger a febrile seizure.
Having a brain seizure can be a terrifying experience. If you have a seizure, there was a problem with too much uncoordinated electrical activity in your brain. In general, a seizure is when too many of your brain cells become excited at the same time. There are two different types of seizures, generalized and partial. With a generalized seizure, your brain has abnormal electrical activity on both sides of your brain. Partial seizures happen when electrical activity surges in one part of your brain. Seizures can happen for many reasons; It may be from high levels of salt or sugar in your blood; brain injury from a stroke or head injury brain problems you are born with or perhaps a brain tumor. Dementia, such as Alzheimer's disease, high fever or illnesses or infections that hurt your brain. Illegal drug use or withdrawal from alcohol or drug use can cause seizures as well. So, what are the signs that someone is having a seizure? Some people with seizures may have simple staring spells, while others have violent, uncontrollable shaking and loss of consciousness. Some people will see flashing lights, others may hallucinate. Some people may have strange sensations, such as tingling, smelling an odor that isn't really there, or emotional changes. Most people who have a seizure for the first time will go to the emergency room. The doctor will do tests to rule out medical causes, such as a stroke. You may have blood tests, CT or MRI scans of your head, or a spinal tap. Treatment depends on the cause of your seizure. For example, if a seizure was caused by fever, treatment will focus on bringing the fever down. Your doctor may send you home with some medicines to help you avoid having more seizures if there is reason to think you are at continued risk of seizures. You should get plenty of sleep and try to keep as regular a schedule as possible, and try to avoid too much stress. Most people with seizures can have a very active lifestyle. Plan ahead for the possible dangers of a certain activity. Avoid any activity where loss of consciousness would be dangerous until it is clear that seizures are unlikely to occur again.
Symptoms
A febrile seizure may be as mild as the child's eyes rolling or limbs stiffening. A simple febrile seizure stops by itself within a few seconds to 10 minutes. It is often followed by a brief period of drowsiness or confusion.
Symptoms may include any of the following:
- Sudden tightening (contraction) of muscles on both sides of a child's body. The muscle tightening may last for several seconds or longer.
- The child may cry or moan.
- If standing, the child will fall.
- The child may vomit or bite their tongue.
- Sometimes, children do not breathe and may begin to turn blue.
- The child's body may then begin to jerk rhythmically. The child will not respond to the parent's voice.
- Urine may be passed.
A seizure lasting longer than 15 minutes, is in just one part of the body, or occurs again during the same illness is not a normal febrile seizure.
The health care provider may diagnose febrile seizure if the child has a tonic-clonic seizure but does not have a history of seizure disorders (epilepsy). A tonic-clonic seizure involves the entire body. In infants and young children, it is important to rule out other causes of a first-time seizure, especially meningitis (bacterial infection of the covering of the brain and spinal cord).
Exams and Tests
With a typical febrile seizure, the examination usually is normal, other than symptoms of the illness causing the fever. Often, the child will not need a full seizure workup, which includes an EEG, head CT, and lumbar puncture (spinal tap).
Further testing may be needed if the child:
- Is younger than 9 months or older than 5 years
- Has a brain, nerve, or developmental disorder
- Had the seizure in only one part of the body
- Had the seizure last longer than 15 minutes
- Had more than one febrile seizure in 24 hours
- Has an abnormal finding when examined
Treatment
The aim of treatment is to manage the underlying cause. The following measures help keep the child safe during a seizure:
- Do not hold down the child or try to stop the seizure movements.
- Do not leave the child alone.
- Lay the child on the ground in a safe area. Clear the area of furniture or other sharp objects.
- Slide a blanket under the child if the floor is hard.
- Move the child only if they are in a dangerous location.
- Loosen tight clothing, especially around the neck. If possible, open or remove clothes from the waist up.
- If the child vomits or if saliva and mucus build up in the mouth, turn the child to the side or on the stomach. This is also important if it looks like the tongue is getting in the way of breathing.
- Do not force anything into the child's mouth to prevent biting the tongue. This increases the risk for injury.
If the seizure lasts several minutes, call 911 or the local emergency number to have an ambulance take your child to the hospital.
Call your child's provider as soon as possible to describe your child's seizure.
After the seizure, the most important step is to identify the cause of the fever. The focus is on bringing the fever down. The provider may tell you to give your child medicines to reduce the fever. Follow instructions exactly on how much and how often to give your child the medicine. These medicines, however, do not reduce the chance of having febrile seizures in the future.
It is normal for children to sleep or be drowsy or confused for a short time right after a seizure.
Outlook (Prognosis)
The first febrile seizure can be frightening for parents. Most parents are afraid that their child will die or have brain damage. However, simple febrile seizures are harmless. There is no evidence that they cause death, brain damage, epilepsy, or learning problems.
Most children outgrow febrile seizures by age 5.
Few children have more than 3 febrile seizures in their lifetime. The number of febrile seizures is not related to future risk for epilepsy.
Children who would develop epilepsy anyway will sometimes have their first seizures during fevers. These seizures most often do not appear like a typical febrile seizure.
When to Contact a Medical Professional
If the seizure lasts several minutes, call 911 or the local emergency number to have an ambulance bring your child to the hospital.
If the seizure ends quickly, drive the child to an emergency room when it is over.
Take your child to the doctor if:
- Repeated seizures occur during the same illness.
- This looks like a new type of seizure for your child.
Call or see the provider if other symptoms occur before or after the seizure, such as:
- Abnormal movements, tremors, or problems with coordination
- Agitation or confusion
- Drowsiness
- Nausea
- Rash
Prevention
Because febrile seizures can be the first sign of illness, it is often not possible to prevent them. A febrile seizure does not mean that your child is not getting the proper care.
Occasionally, a provider will prescribe a medicine called diazepam to prevent or treat febrile seizures that occur more than once. However, no drug is completely effective in preventing febrile seizures.
References
Abou-Khalil BW, Gallagher MJ, Macdonald RL. Epilepsies. In: Jankovic J, Mazziotta JC, Pomeroy SL, Newman NJ, eds. Bradley and Daroff’s Neurology in Clinical Practice. 8th ed. Philadelphia, PA: Elsevier; 2022:chap 100.
Mick NW. Pediatric fever. In: Walls RM, Hockberger RS, Gausche-Hill M, eds. Rosen's Emergency Medicine: Concepts and Clinical Practice. 9th ed. Philadelphia, PA: Elsevier; 2018:chap 166.
Mikati MA, Tchapyjnikov D. Seizures in childhood. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 611.
National Institute of Neurological Disorders and Stroke website. Febrile seizures fact sheet.
Seinfeld S, Shinnar S. Febrile seizures. In: Swaiman KF, Ashwal S, Ferriero DM, et al, eds. Swaiman's Pediatric Neurology: Principles and Practice. 6th ed. Philadelphia, PA: Elsevier; 2017:chap 65.
Version Info
Last reviewed on: 2/24/2022
Reviewed by: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
