What is a febrile seizure?

A febrile seizure is a convulsion triggered by fever (typically ≥38°C / 100.4°F) in children aged 6 months to 5 years who have no prior epilepsy, CNS infection, or metabolic abnormality. They are classified as simple (brief, generalized, single episode in 24 hours) or complex (prolonged, focal, or recurrent within 24 hours).

What is the overall recurrence risk?

Published recurrence estimates vary by cohort and combination of factors. This form counts four factors reported in a prospective cohort and should not be interpreted as an individualized probability or management plan.

Does a febrile seizure cause epilepsy?

The risk of developing epilepsy after a simple febrile seizure is only slightly above the general population rate (~1–2%). Complex febrile seizures carry a somewhat higher risk but still the majority of children do not develop epilepsy.

Should antipyretics prevent recurrence?

Routine prophylactic antipyretics during febrile illness have not been shown to reliably prevent febrile seizure recurrence in clinical trials. They are used for comfort. This calculator does not constitute treatment advice.

Which children need EEG or imaging?

Simple febrile seizures in children 6 months to 5 years with full recovery generally do not require routine EEG or neuroimaging per AAP guidelines. Complex features, signs of CNS infection, or atypical presentations warrant further workup.

Is this tool a substitute for clinical evaluation?

No. This tool is for educational and clinical decision-support purposes only. All management decisions must be made by a qualified clinician based on the individual patient's full history and examination.

Febrile Seizure Risk

Select four cohort-associated recurrence factors to create an educational tally, not an individualized probability or treatment plan.

Clinical Risk Factors

1 Age at first febrile seizure

Under 18 months (higher risk) 18 months or older (lower risk)

2 First-degree family history of febrile seizures

Yes — parent or sibling affected No known family history

3 Temperature at time of seizure

Low fever — below 38.3°C (101°F) (lower threshold = higher risk) Higher fever — 38.3°C (101°F) or above

4 Recognized fever duration before seizure

Less than 1 hour (higher recurrence association) 1 hour or longer

Recurrence-factor checklist

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factors

Based on — risk factor(s)

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Risk Factor	Present

Associations are drawn from the prospective Berg et al. cohort. This equal-weight checklist is not a validated probability model. A clinician must evaluate the child and make all testing or treatment decisions.

Summary

Select four cohort-associated recurrence factors to create an educational tally, not an individualized probability or treatment plan.

How it works

Select the child's age at first febrile seizure.
Indicate whether there is a first-degree family history of febrile seizures.
Select the recorded temperature at the time of the seizure.
Select the duration of recognized fever before the seizure.
The tool counts the displayed cohort-associated factors without assigning an individualized probability.

Use cases

Review cohort-associated factors after a child's first febrile seizure.
Prepare questions for a pediatric clinician.
Learn why recurrence estimates vary between children and cohorts.
Educate medical students and residents about febrile seizure epidemiology.
Support education about recurrence factors without making treatment decisions.

Frequently Asked Questions

Last updated: 2026-09-19 · Reviewed by Nham Vu