Chickenpox doesn’t cause epilepsy, but seizures can occur during chickenpox. Most seizures that happen when you have chickenpox are febrile, caused by a high fever.

Most of the time, chickenpox is an itchy rash, but in rare instances, it can cause complications in children and adults, particularly those with weak immune systems. One rare complication can include seizures that may develop into epilepsy after the virus has passed.

Here’s what you need to know about seizures with chickenpox, what causes them, and whether or not they’ll develop into epilepsy.

Epilepsy is a neurological condition that causes seizures or convulsions. A seizure happens when the electrical signals in the brain surge erratically. Seizures generally last from seconds to a few minutes and affect a person’s consciousness, movements, or mental state.

According to the Centers for Disease Control and Prevention (CDC), a person must have two or more seizures to be diagnosed with epilepsy. The condition may develop without an identifiable cause or be triggered by something such as a virus or infection.

The varicella-zoster virus (VZV) is a highly contagious disease that causes an itchy rash. The virus causes both chickenpox (typically in children and people with compromised immune systems) and shingles (typically in adults).

With chickenpox, a person may develop as many as 500 blisters that start on the trunk and face and then spread to the rest of the body over time. Other symptoms include fever, headache, and tiredness.

The virus generally goes away after 4 to 7 days. It can cause a number of complications as well, including brain infection, bacterial infections, lung infections, bleeding problems, and dehydration.

Chickenpox vaccine

There are two vaccines available for chickenpox:

  • Varivax – contains only the chickenpox vaccine
  • ProQuad – contains the chicken pox vaccine and measles, mumps, and rubella (MMRV)

Both are administered in a two-dose series. These vaccines work by introducing the live (but weakened) virus into a person’s body so the body can build up antibodies to fight the virus later on.

Chickenpox vaccines lower the chance of severe infection and have decreased cases in the United States by around 90%. Children receive either vaccine when they’re between 12 and 15 months old and again when they are between 4 and 6 years old.

People can have seizures related to chickenpox; however, seizures aren’t a main symptom of the virus.

There are two major reasons for seizures that are associated with chickenpox. They can occur during the acute phase of the infection, usually just once or twice, and rarely, chickenpox leads to certain complications that lead to epilepsy.

Chickenpox causes fever, and, as a result, some people, usually children, may experience febrile (fever) seizures with their illness.

Most simple febrile seizures don’t turn into epilepsy and go away when the illness has passed. Around 1 in 20 kids who experience complex febrile seizures may go on to develop epilepsy.

Very rarely, some people may develop a brain infection that can lead to seizures and possibly epilepsy.

Chickenpox-related infections that may cause epilepsy include:

  • Encephalitis: This infection causes an inflammation of the brain. It occurs in approximately one out of every 33,000 to 50,000 cases of VZV. Chickenpox makes up 23% of the viruses that cause encephalitis and result in chronic epilepsy.
  • Meningitis: The infection causes an inflammation of the membranes surrounding the brain. It’s another rare complication of chickenpox that may lead to neurological symptoms such as seizures.

Febrile seizures may occur during chickenpox. They affect between 2 and 5% of children ages 5 and younger. During a febrile seizure, a child becomes stiff, and you may see their limbs twitch. Children may also become unconscious or soil themselves during a febrile seizure. Afterward, the child may be very tired for an hour or so.

Usually, a simple febrile seizure will happen only once during an illness. Complex febrile seizures happen more than once and may last 15 minutes or longer.

While uncommon, the chickenpox vaccine may cause seizures in some children. More specifically, the ProQuad vaccine carries a risk of seizure for children between 12 and 23 months old. The seizures may be caused by fever after the vaccine.

Experts share that these seizures aren’t harmful in the long term for children. They’re isolated to a period of time after the vaccine is given.

Make an appointment with a doctor or healthcare professional if you or your child are experiencing seizures. A doctor will give you a physical exam and go over your medical history and family medical history to help find the root cause.

If you’ve had two or more seizures after your illness or infection has passed, a doctor may order more tests.

  • Electroencephalography (EEG): EEGs measure the electrical activity (brain wave patterns) in the brain. Electrodes are placed on the head and record electrical signals from the brain.
  • Imaging tests: MRI, CT scan, positron emission tomography scan, and other imaging tests allow doctors to visualize the brain and any underlying issues that might be contributing to seizures such as infection. Imaging tests are noninvasive and involve lying in a machine to obtain the images.

Seizures related to chickenpox don’t always evolve into epilepsy.

If seizures continue after your illness, treatment options include:

Some people may need treatment their whole lives. Others can avoid episodes by avoiding triggers. And some people may find that their epilepsy goes away with time.

Febrile seizures are usually limited to the period of illness and don’t typically develop into chronic epilepsy.

The exception is if a child has multiple febrile seizures, which last longer than 10 minutes at a time and affect just one part of the body or happen more than once in a 24-hour period of time. There’s a 10% chance children in this category will develop epilepsy.

Children who have febrile seizures that last longer than 30 minutes have a 30 to 40% chance of developing epilepsy. That said, the condition may not develop for several years after the initial seizure or seizures. In these cases, the seizures may damage the hippocampus and lead to epilepsy or other neurological issues.

Recurrent seizures caused by viral complications, such as encephalitis or meningitis, make up between 1 to 5% of all cases of epilepsy. The outlook will depend on the type of seizures and other health issues a person has. Again, some seizures go away with time. Others require treatment with medication, surgery, or other procedures.

Who’s at risk of developing epilepsy from chickenpox?

People at risk of complications from chickenpox include babies, teens, adults, pregnant people, and people with compromised immune systems. In addition to encephalitis and febrile seizures, this group is at higher risk of bacterial infection, pneumonia, sepsis, bleeding issues, and death.

Can adults receive the chickenpox vaccine?

Yes. While the ProQuad (MMRV) vaccine is only approved for children up to age 12, the Varivax (chickenpox-only) vaccine is approved for children, teens, and adults.

What should I do if I observe a seizure in my child?

Move your child into a recovery position (rolled on their side facing you) and don’t place anything in your child’s mouth. Pay attention to how long the seizure lasts. Call 911 or local emergency services if this is your child’s first seizure, if the seizure lasts for more than 5 minutes, if you believe it’s caused by an infection, or whenever you have other concerns.

Seizures are a possible complication of the chickenpox virus. They’re not a feature of the illness itself. Instead, seizures may be caused by fever or other issues such as the virus spreading to cause a brain infection.

Let a doctor know immediately if you or your child experience seizures during your illness.

While most seizures that occur during chickenpox don’t lead to chronic epilepsy, it’s a possibility. A doctor can provide testing and treatment options for you or your child.