Published: 2 June 2022

Publications

Febrile seizures in children are rare

Published 2 June 2022
Prescriber Update 43(2): 27–28
June 2022

Febrile seizures occur in children with fever and have been reported following vaccination. The Centre for Adverse Reactions Monitoring (CARM) receives about eight reports per year of febrile seizures associated with childhood vaccines.

Febrile seizures

Febrile seizures (also called febrile convulsions) are seizures that occur when a child has a fever.¹ They are an age-dependent phenomenon occurring in 2 to 4 percent of young children, one-third of whom may experience another febrile seizure in the future. Commonly identified risk factors include high fever, viral infection, recent immunisation and a family history of febrile seizures.²

Febrile seizures can occur with any condition that causes a fever. In children, fevers are commonly caused by colds, influenza, and various infections, such as ear infections. There is a small increased risk of febrile seizures following vaccination with inactivated or live-attenuated vaccines. Overall, febrile seizures following vaccination remain a rare adverse event.^3–5

Diagnosis and management

A febrile seizure is a clinical diagnosis defined by the following features:²

• a convulsion associated with an elevated temperature of greater than 38°C
• a child older than 6 months and younger than 6 years of age
• absence of central nervous system infection or inflammation
• absence of acute systemic metabolic abnormality that may produce convulsions
• no history of afebrile seizures.

The majority of febrile seizures end spontaneously, and the child recovers quickly. In these cases, febrile seizures do not require treatment with medicines. More complex cases may require treatment with benzodiazepines.⁶

Children diagnosed with febrile seizures do not generally require follow-up unless they have one or more features of concern:

• more than three seizures
• under 6 months or older than 6 years of age
• seizures lasting longer than 30 minutes
• seizures with focal signs
• seizures that are not tonic-clonic.

In these cases, children should be referred to a paediatrician for additional investigation.^1,6

Information for parents and caregivers

Prescribers should inform parents and caregivers that febrile seizures are generally self-limiting and do not cause long-term brain damage or epilepsy. However, the child may have another febrile seizure in future. Provide parents and caregivers with information on what to do if their child experiences another fever or febrile seizure.^7,8

• There is no way to prevent febrile seizures. Keeping the child cool when they have a fever will make them more comfortable but not prevent a seizure.
• Antipyretics (paracetamol) may help to reduce the fever. Always follow the dosage instructions on the bottle.
• Use simple cooling measures to reduce body temperature (eg, undress to a single layer, make sure the room is not too hot or cold).
• In the event of another seizure, lie the child down on their side, do not put anything in their mouth, wait a few minutes for the seizure to stop and seek medical care as advised. If the seizure does not resolve within 5 minutes, call an ambulance.

The KidsHealth and Health Navigator websites have information for parents and caregivers about febrile seizures.

New Zealand case reports

Between March 1989 and 31 March 2022, the Centre for Adverse Reactions Monitoring (CARM) received 184 reports of febrile seizures/convulsions associated with vaccines. The most frequently reported vaccines were measles-mumps-rubella (MMR), meningococcal B, diphtheria-tetanus-acellular pertussis-polio (DTaP-IPV) and diphtheria-tetanus-acellular pertussis-polio-hepatitis B/Hib (DTaP-IPV-HepB/Hib). It is important to note that multiple vaccines can be administered to a child concomitantly. Therefore, a febrile seizure cannot be isolated to any one vaccine.

Conclusion

Febrile seizures can occur in children with fever, usually due to systemic viral or bacterial infection but may, in rare cases, arise from recent vaccination. Vaccines are a key measure to prevent and reduce the burden of various diseases in children and the wider community. The prognosis for children with febrile seizures is favourable, and therefore, future vaccinations should be encouraged and can be safely administered to children in their usual setting.⁵

References

1. Williams G, Jamison S and Davis S. 2018. Seizures - febrile. In: Starship Clinical Guidelines 20 September 2018. URL: starship.org.nz/guidelines/seizures-febrile/ (accessed 1 April 2022).
2. Millichap J. 2021. Clinical features and evaluation of febrile seizures. In: UpToDate 6 May 2021. URL: uptodate.com/contents/clinical-features-and-evaluation-of-febrile-seizures (accessed 31 March 2022).
3. Centers for Disease Control and Prevention. 2020. Febrile seizures and childhood vaccines 14 August 2020. URL: cdc.gov/vaccinesafety/concerns/febrile-seizures.html (accessed 1 April 2022).
4. Centers for Disease Control and Prevention. 2015. Febrile seizures following childhood vaccinations, including influenza vaccination 4 November 2015. URL: cdc.gov/flu/prevent/febrile.htm (accessed 12 April 2022).
5. Deng L, Wood N and Danchin M. 2020. Seizures following vaccination in children: Risks, outcomes and management of subsequent revaccination. Australian Journal of General Practice 49(10): 644-9. URL: www1.racgp.org.au/ajgp/2020/october/seizures-following-vaccination-in-children (accessed 1 April 2022).
6. Millichap J. 2021. Treatment and prognosis of febrile seizures. In: UpToDate 10 August 2021. URL: uptodate.com/contents/treatment-and-prognosis-of-febrile-seizures (accessed 1 April 2022).
7. KidsHealth. 2015. Febrile Seizures 15 March 2021. URL: kidshealth.org.nz/febrile-seizures (accessed 1 April 2022).
8. Health Navigator. 2022. Febrile seizures 11 April 2022. URL: https://www.healthnavigator.org.nz/health-a-z/f/febrile-seizures/ (accessed 26 May 2022).