The Claim in Context
Febrile seizures are a type of seizure that can occur when an otherwise healthy child develops a fever. They can be scary for parents and caregivers but are usually harmless to the child. These seizures are relatively common in young children and can happen with any condition that causes a fever, such as common colds, the flu, ear infection or roseola. Very rarely, febrile seizures can happen after children receive certain vaccines. Distorting or overstating the risks of febrile seizures following vaccination can cause undue anxiety in parents and caregivers and contribute to vaccine hesitancy. Importantly, vaccines help prevent infections that can lead to febrile seizures.
Key Facts
- Febrile seizures usually occur during the first few hours of a fever and are most common with fevers of 102°F (38.9°C) or above, involve stiffening or shaking in parts of or the entire body, and typically last one to two minutes. Children experiencing febrile seizures may twitch, roll their eyes, and appear unresponsive.
- Simple febrile seizures are relatively common, occurring in 3 to 4 out of every 100 children. They are usually harmless and do not cause long-term health issues.
- While fevers, soreness, mild rash and redness at the injection site are common side effects following immunization, febrile seizures after vaccination are extremely rare.
- Vaccinating children at the recommended age helps prevent febrile seizures by teaching their immune systems to protect against dangerous diseases that can cause them to develop.
- For example, there is a slightly elevated risk of febrile seizures in children aged 12-23 months who receive the combination measles, mumps, rubella and varicella (MMRV) as compared to children who receive the MMR and varicella vaccines separately. However, the overall risk of febrile seizures following these vaccines in this age group is still very low.
- Often, pediatricians will administer the MMR and varicella vaccines separately for children under 2 years. However, some parents prefer the combination shot because it means one fewer injection for their child.
- The American Academy of Pediatrics (AAP) recommends children receive either the combination MMRV vaccine or the MMR and varicella vaccines to protect against serious disease. Parents should talk with their child’s pediatrician to decide what is best for their child.
Evidence Snapshot
Studies have consistently demonstrated that the MMR and MMRV vaccines are safe, effective, and their benefits far outweigh the risks of side effects. Roughly 3 to 5% of children will experience a febrile seizure during their childhood, and the odds of a child experiencing a vaccine-related febrile seizure are dramatically lower than that. Febrile seizures occur in 1 in 1100 to 1400 children immunized with a first dose of MMRV vaccine at 12 through 23 months of age and in 1 in 2500 to 3000 children immunized with a first dose of MMR and varicella vaccines administered in at the same time in separate injections.
Why It Matters
While febrile seizures can be scary to witness, they are generally harmless to children and do not cause long-term health impacts. The benefits of immunizing children against measles, mumps, rubella, and chicken pox (varicella) far outweigh the long-term health risks of vaccine-preventable illnesses like measles, mumps, and rubella, including encephalitis, a dangerous form of brain swelling that often results in brain damage and other neurological deficits.
Experts Say:
“To parents and caregivers, watching their child experience a febrile seizure is no doubt a frightening experience, even though these seizures are almost always harmless to children. The important thing to remember is that most pediatricians will not see a case of a vaccine-induced febrile seizure over the course of their careers—that's how rare they are. Childhood immunizations help protect children from illnesses that increase their risk of developing fevers than can trigger febrile seizures."
— Adam J. Ratner, MD, MPH, FAAP, Member, AAP Committee on Infectious Diseases and editor of the Red Book: 2024–2027 Report of the Committee on Infectious Diseases.
Resources for Further Information
Last Updated
12/04/2025
Source
American Academy of Pediatrics