Febrile seizures cannot be reliably prevented. Despite decades of research, no safe, practical intervention has been shown to stop febrile seizures from occurring in children who are prone to them. This is frustrating news for parents, but understanding why prevention is so difficult, what actually matters during a fever, and which children face higher risk can help you feel more prepared and less powerless.
Why Fever-Reducing Medicines Don’t Prevent Seizures
The most common assumption parents make is that keeping a fever low with acetaminophen or ibuprofen will prevent a seizure. It won’t. A 2009 randomized controlled trial found that children given fever reducers had a seizure recurrence rate of 23.4%, virtually identical to the 23.5% rate in children given a placebo. A Cochrane review confirmed the same finding: antipyretics do not decrease the risk of febrile seizures.
This is because febrile seizures aren’t triggered by how high a fever gets. They appear to be driven by how quickly the brain’s temperature rises, and by the inflammatory response itself. When the body fights an infection, it releases signaling molecules that increase the excitability of brain cells, making them more likely to fire in sync. That synchronized firing is what produces a seizure. By the time you notice a fever and give your child medicine, the rapid temperature rise has already happened. The seizure threshold has already been crossed.
This doesn’t mean you should skip fever reducers entirely. They still help your child feel more comfortable. They just shouldn’t be treated as seizure prevention.
What Triggers Febrile Seizures
Febrile seizures occur in children between about 6 months and 5 years old, when the developing brain is especially sensitive to temperature changes. The combination of a still-maturing nervous system and the body’s inflammatory response to infection creates a window of vulnerability that most children eventually outgrow.
Certain infections carry a higher seizure risk than others. Influenza A is a particularly strong trigger. In one study, nearly 20% of hospitalized children with influenza A experienced febrile seizures, compared to about 12% with parainfluenza and 9% with adenovirus. During peak flu season, influenza A accounted for 35% to 44% of all febrile seizure hospital admissions. Human herpesvirus 6, the virus that causes roseola, is another well-known trigger in younger toddlers.
Genetics also play a significant role. If a parent or sibling has had febrile seizures, a child’s risk is meaningfully higher. Some families carry mutations in genes that affect how brain cells regulate electrical activity. These mutations are inherited in a dominant pattern, meaning a child only needs one copy from one parent to be affected. In most cases, though, the genetic contribution is complex and doesn’t follow a single-gene pattern.
Which Children Are More Likely to Have Another Seizure
About one in three children who have a febrile seizure will have at least one more. Several factors push that probability higher:
- Young age at the first seizure. Children who have their first febrile seizure before 18 months are at greater risk of recurrence.
- Family history. A parent or sibling with febrile seizures increases the odds.
- Low fever at the time of the seizure. Counterintuitively, children who seize at temperatures below 40°C (104°F) are at higher risk for recurrence, likely because their brains have a lower threshold for seizure activity.
- Short interval since the last seizure. If fewer than six months have passed since the previous febrile seizure, recurrence is more likely.
- Frequent fevers. Children who get sick often simply have more opportunities for seizures to occur.
The risk of recurrence drops as a child gets older, regardless of how many seizures they’ve had.
Simple vs. Complex Febrile Seizures
Most febrile seizures are classified as “simple.” A simple febrile seizure lasts less than 15 minutes, involves the whole body (often stiffening followed by rhythmic jerking), doesn’t happen more than once in 24 hours, and the child recovers fully within an hour. These seizures, while terrifying to witness, carry an excellent prognosis. They do not cause brain damage, and the vast majority of children who have them never develop epilepsy.
A “complex” febrile seizure is one that lasts longer than 15 minutes, affects only one side of the body, or occurs more than once within 24 hours. Complex febrile seizures carry a higher risk of later epilepsy, up to five times the risk seen in the general population. Children who have focal seizures (affecting one body area) or febrile seizures lasting more than 30 minutes face roughly ten times the general population’s epilepsy risk. Even so, the absolute risk remains small for most children.
What About Preventive Medications
Certain anticonvulsant medications can reduce the chance of a febrile seizure recurring. Continuous daily treatment with some older antiseizure drugs, and short-term use of a sedative given rectally at the onset of fever, have both been shown to lower recurrence rates. However, the American Academy of Pediatrics does not recommend either approach for children with simple febrile seizures. The reasoning is straightforward: the side effects of these medications, which can include sedation, behavioral changes, and in some cases liver toxicity, outweigh the risks of the seizures themselves.
For children with recurrent or prolonged seizures, a doctor may prescribe a rescue medication to be given if a seizure lasts beyond five minutes. This isn’t prevention in the traditional sense. It’s a way to stop a seizure that’s already happening from becoming dangerously long. Parents of children who have had complex febrile seizures should discuss this option with their pediatrician.
What You Can Actually Do
Since true prevention isn’t possible, the most useful thing you can do is prepare for the possibility of another seizure and know how to respond safely.
If your child has a seizure, do not restrain them and do not put anything in their mouth. Move nearby objects that could cause injury. Once the seizure stops, place your child on their side in a recovery position. Expect them to be sleepy or confused afterward; this is normal and usually resolves within an hour. Call 911 if the seizure lasts longer than five minutes.
Keeping your child up to date on vaccinations, particularly the flu vaccine, may reduce the number of high-fever illnesses they experience. The CDC does not recommend giving fever reducers before or after immunizations to prevent febrile seizures, as this approach hasn’t been shown to work and may blunt the immune response to the vaccine.
Perhaps the most important thing to understand is that simple febrile seizures, while frightening, are not harmful to your child’s brain and do not lead to developmental problems. Children outgrow the susceptibility, typically by age 5 or 6. Knowing that the seizure itself is brief, self-limiting, and not damaging can make it easier to stay calm if it happens again.