Febrile Seizures

What are febrile seizures?

A febrile seizure is a seizure caused by a fever in healthy infants and young children. Any fever may cause a febrile seizure. These seizures may happen when a child has an illness such as a cold, the flu, roseola, chickenpox, COVID-19, RSV (respiratory syncytial virus), or an ear infection. Most febrile seizures occur within 24 hours of a child getting sick. Sometimes, a child may have a seizure before developing a fever.

Having a febrile seizure does not mean a child has epilepsy. Epilepsy involves repeated seizures caused by abnormal electrical signals in the brain that aren’t caused by a trigger such as fever.  

Symptoms of febrile seizures

Symptoms of febrile seizures may include:

• Loss of consciousness or passing out
• Uncontrollable shaking, jerking, or stiffening in the arms or legs (may be the whole body or only part of the body)
• Eye rolling
• Loss of bodily control (such as drooling, vomiting, urinating, or having a bowel movement)

Simple febrile seizures are the most common type. They last a few seconds up to 15 minutes, and happen only once in 24 hours. 

Complex febrile seizures either last longer than 15 minutes, happen more than once in 24 hours, or happen only on one part of a child’s body. They may also be a combination of these.  

A febrile seizure can be frightening for the child – and for parents or caregivers. But simple febrile seizures do not cause long-term health problems. However, if the child has a second seizure, it is more likely to last longer than 15 minutes. A first febrile seizure that lasts longer than 15 minutes doesn’t mean the child will necessarily have more seizures. 

Even longer seizures are generally harmless, but they do increase the person’s risk of developing epilepsy. Although rare, some children—including those with cerebral palsy, delayed development, or other neurological issues—who have had febrile seizures have an increased risk of developing epilepsy. 

Who is more likely to get febrile seizures?

Children between ages of 6 months and 5 years are the most likely to have febrile seizures, with the greatest risk for children between ages 1 and 3 years. Children who were in a neonatal intensive care unit in a hospital for more than 28 days, have developmental delay (take longer to learn certain skills), an infection, or a family history of seizures are also at greater risk. 

Some children who have had one febrile seizure will go on to have another. Certain things increase the risk for more febrile seizures, including:

• Young age—Children who have their first febrile seizure when they are younger than 18 months are at increased risk of having another one. 
• Family history—Children whose family members had febrile seizures are more likely to have more than one seizure.   
• First sign of illness—Children who have febrile seizures before showing other symptoms of an illness are at greater risk of having multiple seizures.
• Low temperature—Children are more likely to have another febrile seizure if they had a relatively low temperature with the first one.

Making sure children receive recommended vaccinations at the recommended age may prevent some febrile seizures. These vaccines protect children against measles, mumps, rubella, chickenpox, influenza, pneumococcal infections, and other conditions that can cause fever and febrile seizures. Rarely, some childhood vaccines may cause a fever as a side effect. If a child has a febrile seizure after vaccination (which is uncommon), the seizure is caused by the fever, not the vaccine. 

How are febrile seizures diagnosed and treated?

Diagnosing febrile seizures

Most of the time, children who have febrile seizures won’t need to be in the hospital unless:

• The child has a serious infection
• The child is younger than age 6 months

To diagnose a febrile seizure, a healthcare provider will review a child's medical history and do a physical exam. To diagnose what’s causing a complex febrile seizure, a healthcare provider may also order an EEG (electroencephalogram), which measures brain electrical activity or an MRI (magnetic resonance imaging) to create pictures of the child’s brain. These tests can help identify whether something else is causing the seizure(s).  

Learn more about neurological diagnostic tests and procedures. 

Treating febrile seizures

Most febrile seizures are over within a couple minutes. Parents and caregivers should stay calm and carefully watch the child. During a febrile seizure, they should:

• Note the start time of the seizure. If it lasts longer than five minutes, call an ambulance. By the time the ambulance arrives, the child’s seizure may have become prolonged (lasting longer than 15 minutes). The child should be taken right away to the nearest medical facility.
• Call an ambulance if the seizure lasts less than five minutes, but the child does not seem to be recovering quickly.
• Take steps to prevent injury during the seizure. This may include putting the child on the floor, since they can fall off a bed or couch during a seizure. Do not restrain or hold the child during the seizure.
• Put the child on his or her side or stomach to prevent choking. When possible, gently remove any objects from the child's mouth. Nothing should ever be placed in the child's mouth during a seizure. These objects can block the airway and make it hard to breathe.
• Seek immediate medical attention if this is the child's first febrile seizure. Once it is over, take the child to the doctor to check for the cause of the fever. This is especially urgent if the child shows symptoms of meningitis, including a stiff neck, extreme sleepiness, breathing problems, or a lot of vomiting. 

Drugs that lower fevers such as acetaminophen or ibuprofen may make the child more comfortable. However, numerous studies have shown that treating a fever does not lower the risk of febrile seizure.

What are the latest updates on febrile seizures?

NINDS, part of the National Institutes of Health (NIH), is the nation’s leading federal funder of research on the brain and nervous system, including research on febrile seizures.

Results from an NINDS-funded study have suggested that children with prolonged febrile seizures are at increased risk of developing epilepsy and that prolonged febrile seizures may injure the brain. MRI may help identify the children at highest risk for developing epilepsy. 

Some children with prolonged febrile seizures that last longer than 30 minutes, called febrile status epilepticus (fSE), are at risk of developing epilepsy. Through mouse models, researchers are studying the role of microglia (immune cells in the brain) in reducing the severity of fSE. Researchers are also exploring approaches targeting microglia in developing treatments for this condition.  

More information about research on febrile seizure research may be found using NIH RePORTER, a searchable database of current and past research projects supported by NIH and other federal agencies. RePORTER also includes links to publications and resources from these projects.

For research articles and summaries on febrile seizures, search PubMed, which contains published research papers from medical journals and other sources.  

How can I or my loved one help improve care for people with febrile seizures?

Clinical trials increase our understanding of febrile seizures with the goal of improving how doctors treat them. Consider participating in a clinical trial so clinicians and scientists can learn more about febrile seizures and related conditions. Clinical research with human study participants helps researchers learn more about a disorder and perhaps find better ways to detect, treat, or prevent disease safely.

All types of study participants are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit the NINDS Clinical Trials site and NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with febrile seizures at Clinicaltrials.gov, a searchable database of current and past federal and private clinical trials.

Learn about related topics

• Epilepsy and Seizures