A febrile seizure usually lasts for less than 5 minutes. Your child will:
They may also be sick and foam at the mouth, and their eyes may roll back.
After the seizure, your child may be sleepy for up to an hour. 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. These seizures sometimes happen 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.
Do not put anything into your child's mouth during a seizure – including medicine – as there's a slight chance they might bite their tongue.
While it's unlikely that there's anything seriously wrong, it's important to get your child checked.
Febrile seizures can often be diagnosed from a description of what happened. It's unlikely that a doctor will see the seizure happening, so it's useful to note:
Further tests, such as a blood test or urine test, may be needed if the cause of your child's illness is not 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:
The cause of febrile seizures is unknown, although they're linked to the start of a high temperature (fever).
There may also be a genetic link to febrile seizures, as the chances of having a seizure are increased if a close family member has a history of them.
In very rare cases, febrile seizures can happen after a child has a vaccination.
About 1 in 3 children who have had a febrile seizure will have another seizure 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 medicines to control high temperatures is not likely to prevent further febrile seizures.
However, there may be exceptional circumstances where medicine to prevent recurrent febrile seizures is recommended.
For example, children may need medicine if they have a low threshold for having seizures during illness, particularly if the seizures last a long time.
In this case, your child may be prescribed medicine 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 children who had a seizure because of illness.
Febrile seizures have been linked to an increased risk of epilepsy.
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 a 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 that 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 have not had febrile seizures have around a 1 to 2 in 100 chance of developing epilepsy.