What is chickenpox? Symptoms, causes and prevention

This article is up to date as of November 13, 2025, and based on vaccine guidance provided by the U.S. Centers for Disease Control and Prevention (CDC). Individual states may adopt their own vaccine policies and recommendations based on local public health assessments and regulatory frameworks. For the most up-to-date information, consult your state or local health department or your health care provider.

Chickenpox is not as common these days, thanks to the varicella vaccine. The varicella-zoster virus (VZV) causes chickenpox, and while cases of chickenpox are down 97 percent in the U.S. since the vaccine came out, infections can still occur. Learn more about chickenpox, common symptoms and ways to manage the itching.

In this article:

What is chickenpox?

Chickenpox is caused by VZV, which can hide in the body after a person recovers from chickenpox. Sometimes VZV can wake up later and cause shingles. Chickenpox gives people a rash, which has tiny bumps that eventually fill with liquid. These bumps can show up all over the body, including inside the mouth. The rash caused by chickenpox can be easy to spot because of its fluid-filled blisters and bumps.

Most people are protected for life after receiving two doses of the chickenpox vaccine. To help minimize spread and contain the illness, early recognition of chickenpox is important.

So, where did the name “chickenpox” come from? One theory is that the rash looks a bit like chickpeas. Maybe the term “chickenpox” is a result of how language changes over time.

What are the signs and symptoms of chickenpox?

Understanding how chickenpox typically runs its course — from the first signs to when the rash scabs over —can help someone know what to expect as the disease progresses and how to treat it.

The rash appears

On average, it takes about 14 to 16 days after exposure to develop chickenpox, but it may take anywhere between 10 and 21 days. Besides the hallmark chickenpox rash, other early symptoms may include a fever, fatigue, loss of appetite and headache. In healthy children, a fever can reach up to 102 degrees Fahrenheit for 2 to 3 days. These symptoms may appear 1 to 2 days before a rash.

The classic sign of chickenpox is a rash that turns into itchy, fluid-filled blisters, which eventually become scabs. The rash may first appear on the chest, back and face. The rash can then spread over the entire body, including inside the mouth, eyelids or genital area. It usually takes about one week for all blisters to become scabs.

The bumps usually break out over a few days. Some people can get up to 500 blisters. They might find a new bump next to an older blister or a flat spot near many blisters. All three types — flat spots, raised bumps and blisters — can show up on the skin at the same time.

Fluid blisters form

The blisters that form during chickenpox play a role in knowing when someone is contagious. Generally, a person with chickenpox remains contagious until all their blisters have crusted over. If the person was vaccinated and still develops chickenpox, their blisters might not crust over. In this case, they’re considered contagious until 24 hours have passed without any new blisters appearing.

The number of blisters someone has also affects how contagious they may be if they have received one dose of the varicella vaccine. Research shows that having fewer than 50 blisters (mild breakthrough chickenpox) makes them about one-third as contagious as someone who hasn’t been vaccinated. On the other hand, if a person has 50 or more blisters, they’re just as contagious as someone who hasn't been vaccinated.

Blisters scab over

When someone has chickenpox, the blisters that form will eventually turn into scabs. Some people can develop as many as 500 blisters during their illness. It typically takes around one week for all these blisters to scab over completely. During the last few days, the blisters finally dry up and get crusty. Scabs begin to form on the skin.

After all blisters have crusted over, a person is less likely to spread chickenpox. This is why health care providers say it’s important to stay home until all the blisters have scabbed over. This helps keep friends and family from getting sick, too.

What causes chickenpox?

As mentioned above, chickenpox is caused by VZV. After a person is exposed, there’s a bit of a waiting game. It can take about 10 to 21 days for the first signs of chickenpox to appear. During this time, the virus is quietly settling in and getting ready to make its presence known.

Is chickenpox contagious?

Yes. Chickenpox is caused by a virus that loves to spread. But how exactly does it go from person to person? Touching someone who is sick can be enough because the virus spreads through direct contact with the rash. In fact, up to 90 percent of people who are not immune and close to someone with chickenpox will also get sick.

A person with chickenpox is contagious 1 to 2 days before the rash begins, until all the chickenpox lesions have scabbed over.

Chickenpox vaccine protection

There’s a way to help the body protect itself against chickenpox. It’s called the chickenpox vaccine or the varicella vaccine. It is 92 percent effective after two doses at preventing all varicella. Health care experts say it’s still the most effective method for dodging those red spots. Most people who are vaccinated with two doses of the chickenpox vaccine will be protected for life.

Here’s how the vaccine works and who may be eligible to get it to help stay spot-free. Speak with a health care provider to determine eligibility.

What is the chickenpox vaccine?

The chickenpox vaccine is like a layer of protection. It uses a weakened version of the varicella-zoster virus to help the body build immunity without actually getting sick in most patients.

Who should get the chickenpox vaccine?

The vaccine is recommended for most people. Health care providers give the vaccine on an age-based schedule. Here’s what the schedule typically looks like:

• For routine 2-dose vaccination, the first dose is typically given between 12 and 15 months of age. A second dose is recommended between 4 and 6 years old.
• For those 13 years and older, health care providers can create vaccination plans for those who have never had chickenpox or received the vaccine.

People who are pregnant, have weakened immune systems or have any kind of cancer should not get the chickenpox vaccine or should wait to receive it under the advice from a health care provider. Here’s what to keep in mind:

• Pregnancy. If a person is or may be pregnant, they should talk to a health care provider about the vaccine. It’s generally recommended to wait until after pregnancy to get vaccinated.
• Weakened immune systems. The vaccine is not generally recommended for those who have human immunodeficiency virus (HIV), acquired immunodeficiency syndrome (AIDS) or other conditions that affect the immune system; those who have certain types of cancer; or those who are on certain therapies that affect the immune system. The vaccine could replicate and cause an infection instead of stimulating a protective immune response.

Why should a person get the chickenpox vaccine?

If a person does get chickenpox after receiving two doses of the vaccine, symptoms are usually milder. That means a person can have fewer spots and a faster recovery. Some common side effects of vaccination include soreness at the site of the injection, mild rash, or temporary pain and stiffness in the joints. The effects are usually minor and go away on their own.

Getting vaccinated lessens the chance of getting sick with chickenpox or spreading the illness to loved ones and the community. Chickenpox cases in the U.S. have dropped by over 97 percent since the vaccine program began.

Chickenpox rash vs. look-alikes: What are some differences?

Below are some infectious viral illnesses that also may cause rashes similar to chickenpox. For a medical diagnosis, consult with a health care provider

Mpox, measles and smallpox (which has been eradicated worldwide since 1977) are all different viruses, but they can also cause rashes. Symptoms like high fever or specific patterns of rash are not typical of chickenpox. If a person wants to ensure they are properly protected, they can speak with a health care provider to help determine their vaccine eligibility.

Chickenpox management

There are lots of ways to help relieve symptoms while fighting off the virus. From soothing baths to distraction techniques, below are some ways a person can help manage those itchy spots.

How can someone help a child with chickenpox?

When the fever strikes, parents can check with a health care provider about using over-the-counter (OTC) acetaminophen, which can help bring the fever down. A health care provider might also recommend a medication to help relieve some of the itchiness.

Some medicines like aspirin aren’t safe to take with chickenpox or for children under age 18. Aspirin can cause brain swelling like encephalitis and Reye’s syndrome. Health experts also say it’s a good idea to skip ibuprofen (like Motrin or Advil) because it might lead to more serious skin problems.

At-home care for chickenpox itching

It can be really tempting to scratch those blisters. But breaking the skin open can lead to bacterial infections and leave scars. Below are some tips to help resist the itch:

People can also consider taking baths with gentle, fragrance-free soap and water. (Using deodorant soaps or soaps marked “unscented” may irritate dry or sensitive skin.) Adding colloidal oatmeal can help soothe itchy skin. Calamine lotions are also recommended.

Antiviral medication

Antiviral medication may be an option for those feeling sick. Antiviral treatment is recommended for people with a higher risk of dangerous illnesses, including:

• Otherwise healthy people over the age of 12
• People undergoing long-term salicylate or steroid therapy
• People with chronic skin or lung disease
• People with weakened immune systems
• Pregnant people

Supporting high-risk groups toward better health

Always consult with a health care provider when chickenpox symptoms start. Health care providers can help high-risk groups get the help they need.