Febrile Seizures Fact Sheet

Febrile Seizures Fact Sheet

What are febrile seizures?
How common are febrile seizures?
What should be done for a child having a febrile seizure?
Are febrile seizures harmful?
How are febrile seizures evaluated?
Can subsequent febrile seizures be prevented?
What research is being done on febrile seizures?
Where can I get more information?


What are febrile seizures?

Febrile seizures are seizures or convulsions that occur in young children and are triggered by fever.  The fever may accompany common childhood illnesses such as a cold, the flu, or an ear infection.  In some cases, a child may not have a fever at the time of the seizure but will develop one a few hours later.

Having a febrile seizure does not mean a child has epilepsy, since that disorder is characterized by reoccurring seizures that are not triggered by fever.  

If a child has a fever, most parents will use fever-lowering drugs such as acetaminophen or ibuprofen to make the child more comfortable.  However, studies show this does not reduce the risk of having another febrile seizure.

Symptoms

Most febrile seizures last only a few minutes and are accompanied by a fever above 101°F (38.3°C).  Young children between the ages of about 6 months and 5 years old are the most likely to experience febrile seizures.  Children are at the greatest risk of having a febrile seizure at age 2.  Symptoms may include:

  • The child will lose consciousness
  •  Both arms and legs will shake uncontrollably
  • Eye rolling
  • Rigid (stiff) limbs

Sometimes during a febrile seizure, a child may lose consciousness but will not noticeably shake or move.

Outlook

Although they can be frightening for parents, brief febrile seizures (less than 15 minutes) do not cause any long-term health problems.  However, if another does occur, it is more likely to be prolonged.  A prolonged initial febrile seizure does not substantially boost the risk of reoccurring febrile seizures.  Even prolonged seizures (lasting more 15 minutes) are generally harmless but do carry an increased risk of developing epilepsy.

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What should be done for a child having a febrile seizure?

Parents and caretakers should remain calm, take first aid measures, and carefully observe the child.  If a child is having a febrile seizure, parents and caregivers should do the following:

  • Note the start time of the seizure.  If the seizure lasts longer than 5 minutes, call an ambulance.  The child should be taken immediately to the nearest medical facility for diagnosis and treatment.
  • Call an ambulance if the seizure is less than 5 minutes but the child does not seem to be recovering quickly.  
  • Gradually place the child on a protected surface such as the floor or ground to prevent accidental injury.  Do not restrain or hold a child during a convulsion.
  • Position 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 obstruct the child's airway and make breathing difficult.
  • Seek immediate medical attention if this is the child’s first febrile seizure and take the child to the doctor once the seizure has ended to check for the cause of the fever.  This is especially urgent if the child shows symptoms of stiff neck, extreme lethargy, or abundant vomiting, which may be signs of meningitis, an infection over the brain surface.

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Are febrile seizures harmful?

The vast majority of febrile seizures are short and do not cause any long-term damage.  During a seizure, there is a small chance that the child may be injured by falling or may choke on food or saliva in the mouth.  Using proper first aid for seizures can help avoid these hazards.

There is no evidence that short febrile seizures cause brain damage.  Large studies have found that even children with prolonged febrile seizures have normal school achievement and perform as well on intellectual tests as their siblings who do not have seizures.  Even when the seizures last a long time, most children recover completely.

Multiple or prolonged seizures are a risk factor for epilepsy but most children who experience febrile seizures do not develop the reoccurring seizures that are characteristic of epilepsy.  

Children who experience a brief, full body febrile seizure are slightly more likely to develop epilepsy than the general population.  Children who have a febrile seizure that lasts longer than 10 minutes; a focal seizure (a seizure that starts on one side of the brain); or seizures that reoccur within 24 hours, have a moderately increased risk (about 10 percent) of developing epilepsy as compared to children who do not have febrile seizures.

Of greatest concern is the small group of children with very prolonged febrile seizures lasting longer than 30 minutes.  In these children, the risk of epilepsy is as high as 30 to 40 percent though the condition may not occur for many years.  Recent studies suggest that prolonged febrile seizures can injure the hippocampus, a brain structure involved with temporal lobe epilepsy (TLE).

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How common are febrile seizures?

Febrile seizures are the most common type of convulsions in infants and young children and occur in 2 to 5 percent of American children before age 5.  Approximately 40 percent of children who experience one febrile seizure will have a recurrence.  

Children at highest risk for recurrence are those who have:

  • Young age.  Children who have their first febrile seizure when they are younger than 18 months are at an 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 exhibiting 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 the first one was accompanied by a relatively low temperature.

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How are febrile seizures evaluated?

Before diagnosing febrile seizures in infants and children, a doctor will review a child’s medical history and perform a physical exam.  Doctors often perform other tests such as examining the blood and urine to pinpoint the cause of the child's fever.  Dehydration from severe diarrhea or vomiting could be responsible for seizures. 

Meningitis, an infection of the membranes surrounding the brain, can cause both fever and seizures that can look like febrile seizures but are much more serious.  If a doctor suspects a child has meningitis, removing and evaluating a small of the cerebrospinal fluid (fluid surrounding the brain and spinal cord) may be needed.  

If the seizure is either very prolonged or is accompanied by a serious infection, or if the child is younger than 6 months of age, the clinician may recommend hospitalization.  In most cases, however, a child who has a febrile seizure usually will not need to be hospitalized.

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Can subsequent febrile seizures be prevented?

The majority of children with febrile seizures to not need medication.  Experts recommend that children who have experienced a febrile seizure not take any antiseizure medication to prevent future seizures, as the side effects of these daily medications outweigh any benefits.  This is especially true since most febrile seizures are brief and harmless.

Children especially prone to febrile seizures may be treated with medication, such as diazepam, when they have a fever.  This medication may lower the risk of having another febrile seizure.  It is usually well tolerated, although it occasionally can cause drowsiness, a lack of coordination, or hyperactivity.  Children vary widely in their susceptibility to such side effects.

A child whose first febrile seizure is a prolonged one does not necessarily have a higher risk of having reoccurring prolonged seizures.  But if they do have another seizure, it is likely to be prolonged.  Because very long febrile seizures are associated with the potential for injury and an increased risk of developing epilepsy, some doctors may prescribe medication to these children to prevent prolonged seizures.  The parents of children who have experienced a long febrile may wish to talk to their doctor about this treatment option.

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What research is being done on febrile seizures?

The National Institute of Neurological Disorders and Stroke (NINDS) is the primary funding agency on research on brain and nervous system disorders and conditions, including epilepsy and seizures.  NINDS is a component of the National Institutes of Health (NIH), the leading supporter of biomedical research in the world. 

Researchers are exploring the biological, environmental, and genetic risk factors that might make children susceptible to febrile seizures.  They are also working to pinpoint factors that can help predict which children are likely to have reoccurring or prolonged febrile seizures.

Investigators continue to monitor the long-term impact that febrile seizures might have on intelligence, behavior, school achievement, and the development of epilepsy.  For example, NINDS-funded scientists are assessing the effects of febrile seizures, especially very prolonged febrile seizures, on brain structures such as the hippocampus, an area of the brain that plays a role in memory and learning.  In addition, researchers are looking at ways that febrile seizures may affect connections between brain cells.  They are also working to determine the impact of these seizures on the development of epilepsy and memory.

Children who have experienced prolonged febrile seizures are more likely to develop a particular type of epilepsy called temporal lobe epilepsy (TLE), which is often difficult to treat.  TLE is associated with scarring of the hippocampus and usually presents in adolescents or young adults, some of whom have a history of long febrile seizures as young children.  Scientists are trying to identify which children will go on to develop TLE in order to develop better treatments to prevent this condition. 

For example, using an electroencephalogram (EEG) to examine the brain’s electrical activity after prolonged febrile seizure may help identify children at risk for ongoing health problems.   

Researchers are using animal models of febrile seizure to understand why they occur and to identify biomarkers that may help track long-term effects.

Investigators are also trying to develop drugs to prevent the occurrence of brain injury, epilepsy, and memory problems following prolonged febrile seizures.

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Where can I get more information?

Information about NINDS research on febrile seizures and other neurological disorders is available from the Institute's Brain Resources and Information Network (BRAIN) at:

BRAIN
P.O. Box 5801
Bethesda, MD  20824
Phone:  301-496-5751 or 800-352-9424
 

Other sources of information on febrile seizures include:

Centers for Disease Control and Prevention (CDC) 
1600 Clifton Road
Atlanta, GA 30329-4027
Email:  CDC-INFO
Phone:  800-232-4636

Epilepsy Foundation
3540 Crain Highway, Suite 675 
Bowie, MD  20716 
Phone:  301-459-3700 or 800-332-1000

Citizens United for Research in Epilepsy (CURE)
420 N. Wabash Avenue, Suite 650 
Chicago, IL 60611
Phone: 312-225-1801 or 844-231-2873

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"Febrile Seizures Fact Sheet", NINDS, Publication date September 2015.

Online information updated June 16, 2021

NIH Publication No. 15-3930

Back to Febrile Seizures Information Page

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Prepared by:
Office of Neuroscience Communications and Engagement
National Institute of Neurological Disorders and Stroke
National Institutes of Health
Bethesda, MD 20892

NINDS health-related material is provided for information purposes only and does not necessarily represent endorsement by or an official position of the National Institute of Neurological Disorders and Stroke or any other Federal agency. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient's medical history.

All NINDS-prepared information is in the public domain and may be freely copied. Credit to the NINDS or the NIH is appreciated.