Febrile Seizures Following Childhood Vaccinations, Including Influenza Vaccination

What to know

The word “febrile” refers to having a fever. A seizure is a convulsion or uncontrolled body movements. A “febrile seizure” refers to a seizure/convulsion associated with a fever in a child. Febrile seizures usually last around one or two minutes and can occur with any condition that causes fever, such as a cold, influenza, or ear infection. They are most common with fevers of 102°F (38.9°C) or higher, but they can also happen at lower body temperatures or when a fever is going down. A person experiencing a febrile seizure may lose consciousness.

Child having a checkup with mask on

ACIP Recommendation

Recommendations of the Advisory Committee on Immunization Practices‎

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2024-2025 Influenza Season has been published.

Children who are likely to have febrile seizures

Most febrile seizures happen in children between the ages of 6 and 59 months. Up to 5% of young children will have at least one febrile seizure. The most common age range for children to have febrile seizures is 14–18 months.

About 1 in 3 children who have one febrile seizure will have more febrile seizures during childhood. If a member of a child's immediate family (a brother, sister, or parent) has had febrile seizures, that child is more likely to have a febrile seizure.

Seriousness of febrile seizures

Febrile seizures can be frightening, but nearly all children who have a febrile seizure recover quickly, are healthy afterwards, and do not have any permanent neurological damage. Febrile seizures do not make children more likely to develop epilepsy or any other seizure disorder.

Febrile seizures are rare after vaccination

Vaccines can cause fevers, but febrile seizures are rare after vaccination. Importantly, getting sick with the flu also can cause febrile seizures.

Flu illness can cause high fever and febrile seizures in children. Flu vaccine can protect children against flu illness and its complications. Flu vaccine cannot cause flu.

Several studies of children in the United States have looked at whether flu vaccination is associated with an increased risk for febrile seizures.

  • Flu vaccine was not found to be associated with febrile seizures in one study that looked at 45,000 children aged 6 months through 23 months of age who received a flu vaccine from 1991 through 20031
  • Seasonal flu vaccine and the 2009 H1N1 flu vaccine were not found to be associated with febrile seizures in children during the 2009-2010 flu season2.
  • Some studies have detected a small increased risk of febrile seizures in young children following the flu shot in some flu seasons. In these studies, the risk of febrile seizures was increased for children 12 through 23 months of age, particularly when the flu shot was given at the same time as pneumococcal conjugate vaccine (PCV133) and diphtheria, tetanus, and pertussis (DTaP)-containing vaccine4.

After carefully reviewed the data on febrile seizures and considering the benefits of vaccinating children against these illnesses, the CDC decided that no changes in the childhood immunization recommendations should be made.

CDC monitoring for the safety of vaccines

CDC and the Food and Drug Administration (FDA) closely monitor the safety of vaccines approved for use in the United States. CDC primarily uses two systems to monitor the safety of flu vaccines:

  1. Vaccine Adverse Event Reporting System (VAERS): an early warning system that helps CDC and FDA monitor problems following vaccination. Anyone can report possible vaccine side effects to VAERS. Generally, VAERS reports cannot determine if an adverse event was caused by a vaccine, but these reports can help determine if further investigations are needed.
  2. Vaccine Safety Datalink (VSD): a collaboration between CDC and eight integrated health care organizations that conducts ongoing vaccine safety monitoring and in-depth analysis of vaccine safety data.

Reporting to CDC

Febrile seizures after a childhood vaccination can be reported to CDC via the Vaccine Adverse Event Reporting System (VAERS). Your doctor might file this report, or you can do it yourself through the VAERS website.

Learn more about febrile seizures

To learn more about febrile seizures, visit the following sites: