What Is Febrile Seizure?

Febrile seizures happen in early childhood and are caused by a fever higher than 100.4 degrees F. The fever usually comes from an illness such as an ear infection, a cold, or influenza. They don’t mean your child has epilepsy.

The seizures typically last for just a few minutes and stop without the need for medical help. While they can be frightening, most febrile seizures don’t cause health problems beyond possibly making the child feel tired.

This article discusses the symptoms, causes, diagnosis, and treatment of febrile seizures.

Types and Symptoms of Febrile Seizures

There are two types of febrile seizures: simple and complex. Simple seizures are the most common, accounting for about 80% of febrile seizures.

Symptoms of simple febrile seizures include:

• Convulsing, shaking, or twitching all over
• Eyes rolling back into the head
• Moaning
• Stiff, rigid limbs
• Vomiting or urinating during the seizure
• Losing consciousness

Simple febrile seizures usually last for just a few minutes, but they can continue for up to 15 minutes. They generally occur only once per illness and may never recur, even when the child has another fever.

A complex febrile seizure has similar symptoms to the simple type and involves:

• Twitching or unusual movement of one body part or one side of the child’s body
• Seizures that last longer than 15 minutes
• More than one seizure in 24 hours or during the illness
• Lingering symptoms for more than an hour after the seizure ends

Causes and Risk Factors of Febrile Seizures

The exact causes of febrile seizures are unknown. However, research suggests a link to some viruses combined with the reaction of a still-developing brain.

Dehydration from prolonged vomiting, diarrhea, or fever, may also contribute to seizures. In some cases, febrile seizures are triggered by heat-related illnesses, such as heat stroke, which involves a high core body temperature, much like a fever.

While they can happen with a fever of 100.4 degrees F, they’re more common at 102 degrees F or higher fevers.

A child is more likely to have a febrile seizure if:

• There’s a family history of febrile seizures.
• They’ve had one in the last year or two.
• They had their first febrile seizure before they were 15 months old.

Otherwise healthy children older than 1 at the time of their first febrile seizure have a 30% chance of having another one. If they’re over a year old when they have their first one, that chance goes down to about 1 in 4.

Risk of Developing Epilepsy

Having a febrile seizure doesn’t mean your child has or will have epilepsy. Some risk factors can make them more likely to develop a seizure disorder. They include: 

• Developmental problems that were present before the seizure
• Complex febrile seizures
• A parent or sibling who has seizures that aren’t fever-related

The more risk factors a child has, the higher their epilepsy risk becomes. For example:

• One risk factor means a 2.5% risk of developing epilepsy.
• Two or three risk factors mean a 5% to 10% risk.

Diagnosis of Febrile Seizures

To diagnose a febrile seizure, your child’s healthcare provider may:

• Do a physical exam and ask about a family history of seizures
• Look for signs of infection 
• Run blood tests, depending on the child’s symptoms
• Perform a spinal tap if meningitis is suspected, especially in a child under a year old
• Order an electroencephalogram (EEG) or magnetic resonance imaging (MRI) to see what’s happening in the brain, especially for prolonged seizures or if other concerns arise

What to Do During a Febrile Seizure

Always get medical attention after a child’s first seizure so they can be properly diagnosed and, if necessary, treated. If your child has a febrile seizure, you can take a few steps to protect them and help their healthcare provider diagnose them properly. You should:

• Gently get your child onto the ground or floor, so they don’t fall.
• Lay them on their side to prevent choking.
• If they have something in their mouth, try to remove it.
• Clear the space around them to prevent injuries.
• Loosen clothing that’s around their head or neck.
• Watch for breathing problems such as bluish lips.
• Time the seizure.

What Not to Do During a Febrile Seizure

You shouldn't do a few things while your child has a febrile seizure. These include:

• Don't try to hold or restrain your child.
• Don't put anything in their mouth—it's a myth that they could bite off their tongue.
• Don't try to give them fever-reducing medication.
• Don't put them in water to cool them off.
  

Treatment of Febrile Seizures

Often, a child does not need treatment after a febrile seizure. The source of the fever may be treated with antibiotics. Dehydration needs to be addressed, as well.

Your healthcare provider may recommend a hospital stay for extremely long seizures or a serious infection. This is more common in babies under 6 months old.

Long-Term Treatment

Febrile seizures rarely need to be treated with daily seizure medications used to treat epilepsy. If your child has had prolonged febrile seizures or you live far away from emergency medical care, your healthcare provider may prescribe a rescue medication to give your child during a seizure. They’re usually reserved for seizures longer than three minutes.

Rescue medications include diazepam gel, which is given rectally, orally, or nasally and midazolam liquid, given nasally.

Summary

Febrile seizures are fever-related convulsions in children between 6 months and 5 years old, usually at temperatures above 100.4 degrees F. They're not a sign of epilepsy. Most are simple febrile seizures, which last for a short time and don't recur during the same illness. Complex febrile seizures last for several minutes and are more likely to reoccur.

Diagnosis usually involves a physical exam, taking a family history, and checking for infection. Blood work, a spinal tap, and brain scans may be used in certain situations. The fever-causing infection may need to be treated. You may be given rescue medication to stop future seizures quickly.