U.S. DEPARTMENT OF HEALTH 

AND HUMAN SERVICES

Public Health Service

National Institutes of Health

Febrile Seizures

Febrile Seizures

What are febrile seizures?

Febrile seizures are convulsions brought on by a fever in infants or small children. 

During a febrile seizure, a child often loses 

consciousness and shakes, moving limbs on 

both sides of the body. Less commonly, the 

child becomes rigid or has twitches in only a 

portion of the body, such as an arm or a leg, or 

on the right or the left side only. Most febrile 

seizures last a minute or two, although some 

can be as brief as a few seconds while others 

last for more than 15 minutes. 

The majority of children with febrile seizures 

have rectal temperatures greater than 102 

degrees F. Most febrile seizures occur during 

the first day of a child’s fever. Children prone 

to febrile seizures are not considered to have 

epilepsy, since epilepsy is characterized by 

recurrent seizures that are not triggered 

by fever. 

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How common are febrile seizures?

Febrile seizures are the most common type of convulsions in infants and young 

children. Approximately one in every 25 

children will have at least one febrile seizure, 

and more than one-third of these children 

will have additional febrile seizures before 

they outgrow the tendency to have them. 

Febrile seizures usually occur in children 

between the ages of 6 months and 5 years 

and are particularly common in toddlers. 

Children rarely develop their first febrile 

seizure before the age of 6 months or after 

3 years of age. The older a child is when the 

first febrile seizure occurs, the less likely 

that child is to have more. 

What makes a child prone to recurrent 

febrile seizures?

A few factors appear to increase a child’s risk of having recurrent febrile seizures, 

including young age (less than 15 months) at 

the time of the first seizure, frequent fevers, 

and having immediate family members with 

a history of febrile seizures. If the seizure 

occurs soon after a fever has begun or when 

the temperature is relatively low, the risk 

of recurrence is higher. A long initial febrile 

seizure does not substantially boost the risk 

of recurrent febrile seizures, either brief 

or long. 

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Are febrile seizures harmful?

Although they can be frightening to parents, the vast majority of febrile 

seizures are short and harmless. During a 

seizure, there is a small chance that the child 

may be injured by falling or may choke from 

food or saliva in the mouth. Using proper first 

aid for seizures can help avoid these hazards 

(see section entitled “What should be done 

for a child having a febrile seizure?”). 

There is no evidence that short febrile 

seizures cause brain damage. Large studies 

have found that children with febrile 

seizures have normal school achievement 

and perform as well on intellectual tests as 

their siblings who don’t have seizures. Even 

when the seizures are very long (more than 

1 hour), most children recover completely, 

but prolonged seizures are a risk factor for 

subsequent epilepsy (seizures without fever).

In other words, between 95 and 98 percent 

of children who experience febrile seizures 

do not go on to develop epilepsy. However, 

although the absolute risk remains small, 

some groups of children, including those 

with cerebral palsy, delayed development, 

or other neurological abnormalities, have 

an increased risk of developing epilepsy. 

The type of febrile seizure also matters: 

children who have prolonged febrile seizures 

(particularly lasting over an hour), or seizures 

that affect only part of the body, or that recur 

within 24 hours, are at somewhat higher risk. 

Among children who don’t have any of these 

risk factors, only 1 in 100 develops epilepsy 

after a febrile seizure. 

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What should be done for a child having 

a febrile seizure?

Seizures are frightening, but it is important that parents and caretakers 

stay calm and carefully observe the child. To 

prevent accidental injury, the child should 

be placed on a protected surface such as 

the floor or ground. The child should not 

be held or restrained during a convulsion. 

To prevent choking, place the child on his 

or her side or stomach. When possible, gently 

remove any objects from the child’s mouth. 

Never place anything in the child’s mouth 

during a convulsion—objects placed in the 

mouth can be broken and obstruct the child’s 

airway. Look at your watch when the seizure 

starts. If the seizure lasts 10 minutes, the 

child should be taken immediately to the 

nearest medical facility for treatment. Once 

the seizure has ended, the child should be 

taken to his or her doctor to check for the 

source of the fever. This is especially urgent 

if the child shows symptoms of stiff neck, 

extreme lethargy, or abundant vomiting.

How are febrile seizures diagnosed 

and treated?

Before diagnosing febrile seizures in infants and children, doctors sometimes 

perform tests to be sure that seizures are not 

caused by something other than simply the 

fever itself. For example, if a doctor suspects 

the child has meningitis (an infection of the 

membranes surrounding the brain), a spinal 

tap may be needed to check for signs of the 

infection in the cerebrospinal fluid (fluid 

that bathes the brain and spinal cord). 

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If there has been severe diarrhea or vomiting, 

dehydration could be responsible for seizures. 

Also, doctors often perform other tests such 

as examining the blood and urine to pinpoint 

the cause of the child’s fever.

A child who has a febrile seizure usually 

doesn’t need to be hospitalized. If the 

seizure is prolonged or is accompanied by 

a serious infection, or if the source of the 

infection cannot be determined, a doctor may 

recommend that the child be hospitalized 

for observation.

How are febrile seizures prevented?

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f a child has a fever, most parents 

will use fever-lowering drugs such as 

acetominophen or ibuprofen to make the 

child more comfortable, although there are 

no studies proving that this will reduce the 

risk of a seizure.

Children especially prone to febrile seizures 

may be treated with the drug diazepam orally 

or rectally whenever they have a fever. The 

majority of children with febrile seizures do 

not need to be treated with medication, but in 

some cases a doctor may decide that medicine 

given only while the child has a fever may 

be the best alternative. 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.

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Prolonged daily use of oral anticonvulsants, 

such as phenobarbital or valproate, to prevent 

febrile seizures is usually not recommended 

because of their potential for side effects and 

questionable effectiveness for preventing 

such seizures.

In addition, some children are prone to have 

very long febrile seizures. When a child has 

had a long febrile seizure, the subsequent 

ones might also be long. Because very long 

febrile convulsions (lasting an hour or 

more) are associated with increased risk 

of developing epilepsy, some doctors will 

suggest that such children be treated with 

a rectal form of the drug diazepam to stop 

the seizure. The parents of a child who had 

a very long febrile seizure may wish to 

consult their doctor about this possibility. 

What research is being done on 

febrile seizures?

T he National Institute of Neurological 

Disorders and Stroke (NINDS), a part 

of the National Institutes of Health (NIH), 

sponsors research on all forms of seizures 

in medical centers throughout the country. 

NINDS-supported scientists are exploring 

the environmental and genetic risk factors 

that might make children susceptible to 

febrile seizures. Scientists are also working 

to pinpoint factors that can help predict 

which children are likely to have recurrent 

or long-lasting febrile seizures. 

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Investigators continue to monitor the longterm impact that febrile seizures might have 

on intelligence, behavior, school achievement, 

and the development of epilepsy. For 

example, scientists conducting studies in 

animals are assessing the effects of febrile 

seizures (and especially very long seizures) 

on measures of intelligence and on the 

development of epilepsy. Scientists are trying 

to determine if children experiencing a long 

febrile seizure are at a higher risk for future 

development of a particular type of epilepsy 

called mesial temporal lobe epilepsy (TLE). 

Mesial TLE is associated with scarring of a 

brain area called the hippocampus. Mesial 

TLE usually presents in adolescents or 

young adults, some of whom have a history 

of febrile seizures as young children.

Investigators also continue to explore which 

drugs can effectively treat or prevent febrile 

seizures and to check for side effects of 

these medicines.

Where can I get more information?

I

nformation 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

301-496-5751

800-352-9424

www.ninds.nih.gov

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Epilepsy Foundation

8301 Professional Place

Landover, MD 20785-7223

301-459-3700 

800-332-1000 

www.epilepsyfoundation.org

Citizens United for Research in Epilepsy 

(CURE)

223 W. Erie, Suite 28W

Chicago, IL 60654

312-225-1801

800-765-7118

www.CUREepilepsy.org

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NIH . . . Turning Discovery Into Health

Prepared by:

Office of Communications and Public Liaison

National Institute of Neurological 

Disorders and Stroke

National Institutes of Health

Department of Health and Human Services

Bethesda, Maryland 20892-2540

NIH Publication No. 12-3930 September 2012