A high fever can be scary, especially in young children. If a child is experiencing a seizure in addition to that fever, the situation can be even more frightening. If your child develops a seizure during a fever — or shortly before it starts — it may be a febrile seizure (or febrile convulsion).
These types of seizures are very common — in fact, they are the most common seizures in children, even those without health problems — and fortunately, they are almost always completely harmless in the long run. It can be helpful to know the signs of febrile seizure, why the vast majority are not dangerous, and what to do when your child has one.
Febrile seizures generally happen when a young person has a high fever of above 100.4 degrees Fahrenheit — often on the first day and in the first hours of fever. These seizures also can happen immediately before the onset of fever. For younger children, a febrile seizure may be the very first sign that the child is ill.
During the seizure, the child will most likely have convulsions: a loss of consciousness with shaking of the arms and legs on both sides of the body. Sometimes, the child might lose consciousness but not exhibit any of these movements. Less common symptoms include eye-rolling and stiffness of the arms and legs.
Risk factors for these types of seizures include age, family history, and anything that causes a fever.
Children between 6 months and 5 years of age are at increased risk of febrile seizures, even when they are otherwise healthy.
“Febrile” means “marked or caused by a fever.” As the name implies, febrile seizures happen while the child has a fever or is about to have one. It therefore makes sense that anything that can cause a fever may provoke a febrile seizure. Importantly, the fever and not the underlying infection is the cause of seizure.
Common infections are often the cause of a fever. Common childhood illnesses include the common cold, the flu, or ear infections. Viral infections such as roseola are more often the culprit, but bacterial infections such as pneumonia or meningitis (infection of the tissues surrounding the brain) can also cause high fevers.
Illnesses that are preventable with vaccination can also result in fevers that provoke febrile seizures — these include diseases such as measles, mumps, and rubella.
Researchers believe there may be genetic involvement in febrile seizures. Children with parents who have their own history of febrile seizures may be more likely to have them.
Nearly all febrile seizures are completely harmless to children in the long term and do not lead to the development of any sort of seizure disorder (such as epilepsy). Most children who have a febrile seizure for the first time do not have any more in the future.
About 4 out of 10 children who have a febrile seizure for the first time will have a recurrent febrile seizure, but they will most likely completely outgrow them.
There are two main types of febrile seizures: simple (or “typical”) and complex.
Typical febrile seizures carry no increased risk of brain damage or epilepsy at all, especially after the cause of the fever is addressed. These seizures will usually last no more than 15 minutes, with no more than one seizure in a single 24-hour period. Simple seizures also affect both sides of the body.
Febrile seizures are complex, or atypical, if they last longer than 15 minutes, occur more than once in a 24-hour period, or affect just one side of the body. However, children almost always outgrow these types of seizures, and they carry only a slightly higher risk of developing epilepsy.
Anti-fever drugs like ibuprofen or acetaminophen (Tylenol) can be used to resolve the fever, but they neither prevent febrile seizures nor lower the risk of them happening again.
Anti-seizure medications, which are normally used to prevent seizures for people living with epilepsy, usually are not used to treat children with febrile seizures. Febrile seizures are usually harmless, and these medications carry a risk of side effects.
About 40 percent of children who have their first febrile seizure will have a second one sometime before they turn 6. The risk of having a second febrile seizure increases to 50 percent for children who have their first seizure before the age of 1. However, nearly all children will eventually outgrow their febrile seizures.
Here’s a brief summary of what to do should your child have a febrile seizure:
Having a febrile seizure does not mean your child has epilepsy. Epilepsy is diagnosed when a person has recurrent seizures that are unprovoked. A febrile seizure is an example of a provoked seizure: Something happens to the brain (in this case a fever, perhaps from another infection) that then causes the seizure. Unprovoked seizures have no identifiable immediate cause.
However, you should always seek medical advice and get the opinion of your health care team if your child ever experiences a febrile seizure. In some cases, they may need to run additional tests to understand the cause of the fever and identify any serious infection that provoked the seizure itself. An example is meningitis, which may require brain monitoring (an electroencephalography or EEG) or a lumbar puncture (spinal tap).
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