Overview

A febrile seizure is a convulsion in a child that's caused by a fever. The fever is often from an infection. Febrile seizures occur in young, healthy children who have normal development and haven't had any neurological symptoms before.

It can be frightening when your child has a febrile seizure. Fortunately, febrile seizures are usually harmless, only last a few minutes, and typically don't indicate a serious health problem.

You can help by keeping your child safe during a febrile seizure and by offering comfort afterward. Call your doctor to have your child evaluated as soon as possible after a febrile seizure.

Symptoms

Usually, a child having a febrile seizure shakes all over and loses consciousness. Sometimes, the child may get very stiff or twitch in just one area of the body.

A child having a febrile seizure may:

  • Have a fever higher than 100.4 F (38.0 C)
  • Lose consciousness
  • Shake or jerk the arms and legs

Febrile seizures are classified as simple or complex:

  • Simple febrile seizures. This most common type lasts from a few seconds to 15 minutes. Simple febrile seizures do not recur within a 24-hour period and are not specific to one part of the body.
  • Complex febrile seizures. This type lasts longer than 15 minutes, occurs more than once within 24 hours or is confined to one side of your child's body.

Febrile seizures most often occur within 24 hours of the onset of a fever and can be the first sign that a child is ill.

When to see a doctor

See your child's doctor as soon as possible after your child's first febrile seizure, even if it lasts only a few seconds. Call an ambulance to take your child to the emergency room if the seizure lasts longer than five minutes or is accompanied by:

  • Vomiting
  • A stiff neck
  • Breathing problems
  • Extreme sleepiness

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Causes

Usually, a higher than normal body temperature causes febrile seizures. Even a low-grade fever can trigger a febrile seizure.

Infection

The fevers that trigger febrile seizures are usually caused by a viral infection, and less commonly by a bacterial infection. The flu (influenza) virus and the virus that causes roseola, which often are accompanied by high fevers, appear to be most frequently associated with febrile seizures.

Post-vaccination seizures

The risk of febrile seizures may increase after some childhood vaccinations. These include the diphtheria, tetanus and pertussis vaccine and the measles-mumps-rubella vaccine. A child can develop a low-grade fever after a vaccination. The fever, not the vaccine, causes the seizure.

Risk factors

Factors that increase the risk of having a febrile seizure include:

  • Young age. Most febrile seizures occur in children between 6 months and 5 years of age, with the greatest risk between 12 and 18 months of age.
  • Family history. Some children inherit a family's tendency to have seizures with a fever. Additionally, researchers have linked several genes to a susceptibility to febrile seizures.

Complications

Most febrile seizures produce no lasting effects. Simple febrile seizures don't cause brain damage, intellectual disability or learning disabilities, and they don't mean your child has a more serious underlying disorder.

Febrile seizures are provoked seizures and don't indicate epilepsy. Epilepsy is a condition characterized by recurrent unprovoked seizures caused by abnormal electrical signals in the brain.

Recurrent febrile seizures

The most common complication is the possibility of more febrile seizures. The risk of recurrence is higher if:

  • Your child's first seizure resulted from a low-grade fever.
  • The febrile seizure was the first sign of illness.
  • An immediate family member has a history of febrile seizures.
  • Your child was younger than 18 months at the time of the first febrile seizure.

Prevention

Most febrile seizures occur in the first few hours of a fever, during the initial rise in body temperature.

Giving your child medications

Giving your child infants' or children's acetaminophen (Tylenol, others) or ibuprofen (Advil, Motrin, others) at the beginning of a fever may make your child more comfortable, but it won't prevent a seizure.

Use caution when giving aspirin to children or teenagers. Though aspirin is approved for use in children older than age 3, children and teenagers recovering from chickenpox or flu-like symptoms should never take aspirin. This is because aspirin has been linked to Reye's syndrome, a rare but potentially life-threatening condition, in such children.

Prescription prevention medications

Rarely, prescription anticonvulsant medications are used to try to prevent febrile seizures. However, these medications can have serious side effects that may outweigh any possible benefit.

Rectal diazepam (Diastat) or nasal midazolam might be prescribed to be used as needed for children who are prone to long febrile seizures. These medications are typically used to treat seizures that last longer than five minutes or if the child has more than one seizure within 24 hours. They are not typically used to prevent febrile seizures.

Feb. 24, 2021
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