Chickenpox and epilepsy: what you need to know

Does your child have itchy blisters on their body, a high temperature and a loss of appetite? They could well have chickenpox. 

Chickenpox - also known as varicella - is a very common and highly contagious disease. Until the 1990s, almost all Americans got chickenpox at least once in their life. It has become less common in recent years thanks to the success of the vaccination program, which began in 1995.

You may have heard people talking about possible links between chickenpox and epilepsy. Here is everything you need to know about chickenpox and seizures, as well as chickenpox vaccines, to put your mind at ease.

What is chickenpox?

Chickenpox is a very common and contagious disease. It causes an itchy rash that appears as lots of small blisters all over the body. For most people, chickenpox is merely uncomfortable and passes on its own in a couple of weeks. But for people with weakened immune systems, pregnant women, or very young children, it can lead to complications. These include hospitalization and, in extremely rare cases, death.

Fortunately, there is a very effective vaccine against chickenpox which prevents these complications. Children usually need two chickenpox vaccines – one at around 12-15 months, a second between the ages of four and six.

If you want to learn more about chickenpox, the Centers for Disease Control (CDC) provides reliable information about the disease. 

What is epilepsy?

Epilepsy is a neurological condition where electrical discharges in the brain cause a person to have two or more seizures. There are many different kinds of epilepsy and people develop seizures for various reasons at different stages in their life. 

Epileptic seizures can look very different from one person to the next. They range from tonic clonic seizures - where the person falls to the ground and has convulsions - through to very short spasms where the person remains aware of what is going on.

To learn more about epilepsy, read our introductory blog. 

Is there a link between chickenpox and epilepsy?

When people have chickenpox, they may develop a fever. Sometimes, a fever can lead to febrile seizures which is when a high body temperature triggers a seizure (between 2% and 5% of American children have a febrile seizure before the age of five). 

Febrile seizures might make your child have convulsions (shaking). They could also foam at the mouth, their eyes could roll back, and they may be unresponsive for a few minutes. This can be scary for parents, but for most children, febrile seizures pass very quickly and don’t have any long lasting consequences.

That said, a very small number of children who have febrile seizures do go on to develop epilepsy. This is when they have two or more ‘unprovoked seizures’ (this means when they have seizures without a fever).

The risk here is low. Less than 2% of children who have febrile seizures develop epilepsy (the percentage is a little higher if there is a family background of epilepsy or the child has complex febrile seizures - lasting 15 minutes or more).

Chickenpox isn’t the only cause of febrile seizures – they can also be caused by the flu, a cold or an ear infection, for example.  

Kids and seizures: What causes epilepsy in children?

Vaccine for chickenpox and seizures

Some parents and carers are concerned about the risks of giving their child the vaccine for chickenpox. Parents may be concerned about the vaccine for chickenpox and seizures.

There are two kinds of vaccine that for chickenpox in the United States:

• Varivax®: When administered on its own, Varivax® almost never leads to febrile seizures (less than 1 in 1,000 people develop febrile seizures after getting this vaccine).
• ProQuad®: This is a combination vaccine which contains vaccinations for measles, mumps and rubella, as well as chickenpox (it is sometimes known as MMRV). This vaccine does have a slightly higher risk of causing febrile seizures (between 1 and 2 per 1,000). Researchers point out that the risk of getting a febrile seizure from MMRV is still lower than from getting a cold.

While parents have a right to say they don’t want their kids to get vaccinated, it’s important to thoroughly research the pros and cons. Not getting vaccinated means your child is more likely to get sick from chickenpox, is more likely to develop febrile seizures, and is at a risk of other chickenpox complications - including hospitalization. 

Related: Epilepsy and the COVID vaccines

Who to speak to if you're concerned about chickenpox and epilepsy

If you are worried about the risk of your child developing epilepsy after having chickenpox, a febrile seizure, or getting the varicella vaccine, speak to their doctor. They can give you all the information you need to make the most informed decision for your child.