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Febrile Seizure

NICE CKS Febrile seizure. Last revised: Jan 2024.

Background Information

Febrile seizure: seizure accompanied by fever (>38°C) in the absence of CNS infection that occurs in those aged 6 months - 5 y/o.

The exact cause is unknown.

Strong risk factors:
  • High fever (risk increases with the height of temperature, rather than how rapidly the temperature rises)
 
  • Viral infection is the cause of fever in 80% cases
    • HHV-6 (roseola infantum) and influenza viruses are the most common
 
  • Genetic association
    • Positive family history of seizure (in 1/3 patients)

Note that febrile seizures are generally benign with a normal cognitive outcome (esp. simple febrile seizures).

Possible complications:
  • Parental / carer anxiety
  • Recurrence (~1/3 will experience another febrile seizure)
    • If recurrence does happen, most will happen within 1-2 years
  • Development of epilepsy
    • 1-2% if simple febrile seizure
    • 6-8% if complex febrile seizure

Diagnosis Guidelines

Shared features:
  • 6 m/o - 5 y/o
  • Seizure occurs in the context of febrile illness (typically within the 1st day of illness)
  • High fever (average ~39°C)

Febrile seizures can be classified as simple or complex, and it is important to guide investigations and management.
 
  Simple febrile seizure Complex febrile seizure
Duration <15 min (usually <5 min) >15 min
Type Generalised tonic-clonic Focal seizure
Recurrence No recurrence Seizure recurrence within 24 hours / within the same febrile illness
Recovery Complete recovery in <1 hour Recovery takes >1 hour +/- prolonged post-ictal drowsiness or Todd's palsy (transient hemiparesis)
 

A simple febrile seizure is a clinical diagnosis
  • The seizure itself does not require investigations (i.e. standard seizure workup - EEG, bloods, neuroimaging is not required)
  • Instead, evaluate and investigate the source of fever (e.g. clinical examination, urinalysis)

Investigations are only necessary if the referral is needed (see below) and the choice of investigation depends on what needs to be excluded.

Management Guidelines

Give standard first aid care and record the starting time.

If the seizure lasted for >5 min:
  • Call an ambulance (if not in healthcare setting / in primary care)
  • Give benzodiazepine (buccal midazolam / rectal diazepam) - if advised by a specialist

Immediate hospital assessment if ANY of the following:
  • 1st febrile seizure (or subsequent febrile seizure but has not had specialist assessment)
  • <3 m/o (all <3 m/o children with ≥38°C requires immediate referral)
  • Complex febrile seizure (any of the features)
  • Focal neurological deficit
  • ↓ Level of consciousness prior to seizure
  • Recent use of antibiotics (may mask signs of CNS infection)
  • Parental / carer anxiety and/or difficulty coping

 

If there is another suspected serious / life-threatening source of fever (e.g. meningitis, pneumonia, sepsis) → arrange emergency ambulance transfer.

There is no specific long-term management:
  • Educate on the nature of febrile seizures (see the complication and prognosis section above)
  • Ensure the child completes all childhood immunisations as per schedule (no need for modification, live vaccines are safe)
  • Educate on how to manage further febrile illness and febrile seizures (see below)

  

Do NOT routinely prescribe prophylactic antipyretics or antiepileptic drugs following a febrile seizure unless on the advice of a specialist.

  • Use of antipyretics (e.g. paracetamol and/or ibuprofen) at the onset of fever is not recommended - this does not reduce or prevent febrile seizure recurrence
  • Paracetamol and/or ibuprofen should only be used to reduce the fever if the child is uncomfortable or distressed

  • Advise on immediate first aid measures and when to call an ambulance (if seizure activity lasts >5 min)
  • Benzodiazepine rescue medication - only if advised by a specialist

References

Author: Adams Lau
Reviewer:
Last edited: 25/08/25