Health A to Z
Febrile seizures (febrile convulsions) are fits that can happen when a child has a fever. They most often happen between the ages of six months and three years.
It can be frightening and distressing to see your child having a seizure, particularly if it's their first one.
However, the fits are usually harmless and almost all children make a complete recovery afterwards.
As a precaution, you may still need to take your child to the nearest hospital or dial 999 for an ambulance – see what to do during a seizure.
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A febrile seizure usually lasts for less than five minutes. Your child will:
They may also vomit and foam at the mouth, and their eyes may roll back.
After the seizure, your child may be sleepy for up to an hour afterwards. A straightforward febrile seizure like this will only happen once during your child's illness.
Occasionally, febrile seizures can last longer than 15 minutes and symptoms may only affect one area of your child's body.
These are known as complex febrile seizures. The seizure sometimes happens again within 24 hours or during the period in which your child is ill.
If your child is having a febrile seizure, place them in the recovery position. Stay with your child and try to make a note of how long the seizure lasts.
Don't put anything into your child's mouth during a seizure – including medication – as there's a slight chance they might bite their tongue.
Take your child to the nearest hospital or dial 999 for an ambulance if:
While it's unlikely that there's anything seriously wrong, it's important to get your child checked.
If your child has had febrile seizures before and the seizure lasts for less than five minutes, phone your GP or NHS 111 for advice.
You should also contact your GP or NHS 111 if your child shows signs and symptoms of dehydration, a lack of fluid in the body.
Febrile seizures can often be diagnosed from a description of what happened. It's unlikely that a doctor will see the seizure, so it's useful to note:
Further tests, such as a blood or urine sample, may be needed if the cause of your child's illness isn't clear.
It can sometimes be difficult to get a urine sample from young children, so it may have to be done in hospital.
Further testing and observation in hospital is also usually recommended if your child's symptoms are unusual or they're having complex febrile seizures, particularly if they're younger than 12 months old.
The tests that may be recommended include:
A lumbar puncture can be used to determine whether your child has an infection of the brain or nervous system.
The cause of febrile seizures is unknown, although they're linked to the start of a fever, a high temperature of 38C (100.4F) or above.
There may also be a genetic link to febrile seizures – the chances of having a seizure are increased if a close family member has a history of them.
In rare cases, febrile seizures can occur after a child has a vaccination.
Research has shown children have a 1 in 3,000 to 4,000 chance of having a febrile seizure after having the MMR vaccine.
The risks are even lower with the DTaP/IPV/Hib vaccine – a 1 in 11,000 to 16,000 chance.
About a third of children who have had a febrile seizure will have another one during a subsequent infection. This often happens within a year of the first one.
Recurrence is more likely if:
It's not recommended that your child is given a prescription of regular medicines to prevent further febrile seizures.
This is because the adverse side effects associated with many medicines outweigh any risks of the seizures themselves.
Research has shown the use of medication to control fever isn't likely to prevent further febrile seizures.
However, there may be exceptional circumstances where medication to prevent recurrent febrile seizures is recommended.
For example, children may need medication if they have a low threshold for having seizures during illness, particularly if the seizures are prolonged.
In this case, your child may be prescribed medications such as diazepam or lorazepam to take at the start of a fever.
Children who've had a febrile seizure after a routine vaccination – which is very rare – are no more at risk of having another seizure than those whose seizure was from illness.
Febrile seizures have been linked to an increased risk of epilepsy, as well as other problems.
Recent research findings may indicate a link between febrile seizures and sudden unexplained death in childhood (SUDC), possibly because of the connection between febrile seizures and epilepsy.
But this link hasn't been proven and SUDC is incredibly rare, affecting around 1 in 100,000 children – equivalent to a 0.001% chance.
One of the biggest studies of its kind looked at more than 1.5 million children with a history of febrile seizures and found no evidence of an increased risk of death in later childhood or adulthood.
Many parents worry that if their child has one or more febrile seizures, they'll develop epilepsy when they get older. Epilepsy is a condition where a person has repeated seizures without fever.
While it's true that children who have a history of febrile seizures have an increased risk of developing epilepsy, it should be stressed that the risk is still small.
It's estimated children with a history of simple febrile seizures have a 1 in 50 chance of developing epilepsy in later life.
Children with a history of complex febrile seizures have a 1 in 20 chance of developing epilepsy in later life.
People who haven't had febrile seizures have around a 1 in 100 chance.