Febrile seizures are seizures associated with fever in young children who do not have a central nervous system infection, acute metabolic cause or previous unprovoked seizures. They are common and are not the same thing as epilepsy.
The usual age range
Classic febrile seizures most often occur between about six months and five years of age. Definitions vary slightly between organisations and studies.
A fever-associated seizure outside the usual age range deserves careful assessment rather than automatically being labelled a typical febrile seizure.
Simple and complex febrile seizures
A simple febrile seizure is usually generalised, brief and occurs once during a febrile illness.
Features commonly used to define a complex febrile seizure include focal onset, prolonged duration or more than one seizure during the same febrile illness.
A febrile seizure is not automatically epilepsy
Epilepsy implies an enduring predisposition to unprovoked or reflex epileptic seizures. A seizure provoked by fever in the typical febrile-seizure setting is different.
Most children who have a febrile seizure do not go on to develop epilepsy.
There is still an association with later epilepsy
The risk of later epilepsy is higher after febrile seizures than in children who have never had one, but the absolute risk remains low for most children.
Risk is higher in some groups, including children with complex features, developmental abnormalities, a family history of epilepsy or repeated febrile seizures. These are risk associations, not predictions for an individual child.
Febrile seizures plus and genetic epilepsies
Some genetic epilepsies include fever-sensitive seizures. Genetic Epilepsy with Febrile Seizures Plus (GEFS+) is a familial spectrum in which febrile seizures may persist beyond the usual age range or occur alongside unprovoked seizures.
Dravet syndrome can also begin with prolonged fever-sensitive seizures in infancy. These conditions are not the same as ordinary febrile seizures.
Febrile status epilepticus
A prolonged febrile seizure can meet criteria for status epilepticus and requires emergency management.
Having febrile status epilepticus still does not by itself prove that a child has epilepsy, but it may change the level of investigation and follow-up.
Evaluation focuses on the child and the illness
The immediate assessment is not simply ‘was there a seizure?’ Clinicians must consider the cause of the fever, the child’s age and development, whether there are signs of meningitis or encephalitis, and whether the event was truly a febrile seizure.
Routine EEG or neuroimaging is not required after every simple febrile seizure; investigations depend on the clinical context.
Related reading
Sources and further reading
- Best practices for the management of febrile seizures in children — 2024
- Risk factors for epilepsy following febrile seizures — 2024 meta-analysis
- Febrile seizures: clinical review and caregiver education — 2024
Evidence checked: September 2026.