Febrile Seizure
On this page
Direct answer
One generalised seizure of two minutes with fever in a previously healthy eighteen-month-old, alert within the hour, is a simple febrile seizure — a benign age-linked reaction between six months and five years that needs a cause for the fever, not an electroencephalogram. The seizure becomes complex when any one of focal onset, duration beyond fifteen minutes, or recurrence within twenty-four hours applies. Active seizures past five minutes are aborted with buccal or intranasal midazolam; recurrence risk runs about a third overall, half under a year of age, and later epilepsy risk stays around one to two per cent for simple seizures.
What you must remember
- Definition: a seizure with fever of 38°C or more in a child aged 6 months to 5 years, with no CNS infection, no metabolic derangement and no prior unprovoked seizures; peak incidence 12–18 months, with a strong family history usual.
- Simple: generalised, under 15 minutes, not repeating within 24 hours, no focal features; complex: focal onset, over 15 minutes, or recurrent within 24 hours — any single criterion suffices.
- First aid: recovery position, nothing forced into the mouth, note the time; past 5 minutes give buccal or intranasal midazolam about 0.2 mg per kg, repeated once after 10 minutes, or rectal diazepam where that is the available route.
- After the seizure, find the fever's source — viral upper respiratory infection leads; examine for meningeal signs and check glucose if the child is not fully alert.
- Lumbar puncture is reserved for meningeal signs, persisting altered consciousness, incomplete immunisation in a young infant, prior antibiotics that could mask meningitis, or genuine doubt — a simple febrile seizure alone never mandates the tap.
- Electroencephalography and neuroimaging are not indicated after a simple febrile seizure; ordering them is the classic over-investigation trap.
- Recurrence predictors: first seizure under 12–15 months, family history of febrile seizures, low fever at the seizure, brief fever-to-fit interval; overall recurrence about 30–35 per cent.
- Epilepsy risk stays low, about 1–2 per cent after a simple seizure, climbing when complex features, neurological abnormality or family epilepsy stack up.
- Continuous antiepileptics are never given; antipyretics comfort the child but do not prevent recurrence — a favourite counselling point.
The consultation that is mostly talking
A nineteen-month-old had a two-minute generalised seizure an hour into a fever and is now running about the ward; the parents are convinced her brain is damaged. The medical half takes ten minutes: confirm simple criteria from the history, examine — red throat, no neck stiffness, normal sensorium — and name the viral source. The professional half takes the rest of the hour: the seizure came from the fever's rate of rise, not its height; most children never have another; what to do at home — recovery position, timing, midazolam if it exceeds five minutes, nothing forced into the mouth; and the return triggers — over five minutes, a second one the same day, one-sided movements, or a child not herself afterwards. An exam-worthy point: round-the-clock paracetamol does not prevent the next one. Had this been a focal seizure lasting twenty minutes with a postictal arm weakness, the label would change to complex, observation would tighten, and neurology follow-up would be justified — still without a routine electroencephalogram unless the history suggests more.
Where students slip
The loudest errors are investigative: electroencephalograms and computed tomography after a simple seizure, and lumbar punctures done routinely rather than for the listed indications. The management errors follow: daily antiepileptics to prevent recurrence, or promising that paracetamol prophylaxis works. The mirror-image slip is so much reassurance that the red flags go unmentioned; a febrile seizure under six months, with a stiff neck or a flat conscious level, is meningitis territory and the tap is back on the table. And in the actively seizing child, the correct first move in the community is buccal midazolam, not a tourniquet.
Frequently asked questions
What makes a febrile seizure complex rather than simple?
Any one of: focal onset, duration longer than 15 minutes, or recurrence within 24 hours; simple seizures are generalised, brief and non-recurring.
How is a febrile seizure lasting over five minutes treated?
Buccal or intranasal midazolam at about 0.2 mg per kg, repeated once after 10 minutes; hospitals may use intravenous lorazepam or diazepam, then reassess the fever's cause.
When is a lumbar puncture indicated after a febrile seizure?
For meningeal signs, persisting altered consciousness, incomplete immunisation in infancy, pretreatment with antibiotics, or diagnostic uncertainty — not for a simple seizure with an evident viral source.
What is the chance of recurrence?
About a third overall; nearer half if the first seizure came under 12–15 months, or with a family history or a low fever at the seizure.
Do febrile seizures lead to epilepsy?
Simple febrile seizures carry a low risk, around 1–2 per cent; complex features, pre-existing neurological abnormality and family epilepsy raise it substantially.
Do antipyretics prevent recurrent febrile seizures?
No — paracetamol and ibuprofen make the child comfortable but do not change recurrence, and continuous antiepileptics are not used for this benign condition.