What Is Chickenpox?

The varicella-zoster virus causes chickenpox. It is a highly contagious disease that leads to an itchy rash, fever, and fluid-filled blisters. Chickenpox primarily affects children under age 12, but adults can also get it.

Chickenpox is a mild illness that clears up after a week or two. However, it can be severe, especially for pregnant people, babies, and those with a weakened immune system.

This article reviews everything you need to know about chickenpox.

Young boy with chicken pox playing on a cell phone while caregiver is touching his forehead
SBDIGIT / Getty Images.

What Causes Chickenpox?

Varicella-zoster is the virus that causes chickenpox. While anyone can get chickenpox, it is most common in children under 12. 

Chickenpox is highly contagious and spreads from person to person. You can get it from respiratory droplets when someone coughs, sneezes, or through direct contact. Direct contact means touching the chickenpox sore or a contaminated object and then your mouth or nose.

Chickenpox Immunity and Risk

A person is immune if they have had chickenpox or the vaccine. Nonimmune people are those who have not had chickenpox or the vaccine. If someone gets chickenpox, up to 90% of the nonimmune people close to that person will get the infection. 

Chickenpox Symptoms

Chickenpox symptoms usually appear within 10 to 21 days after exposure. The most classic symptom of chickenpox is an itchy rash that turns into fluid-filled blisters. Chickenpox can cause 200–500 blisters to develop over the body.

Initially, a chickenpox rash looks like red, itchy bumps on the face, chest, and back. It then spreads to other body parts, including the mouth, eyelids, or genital area. 

The itchy bumps turn into fluid-filled blisters that are almost see-through. Once the blisters break, the sores start to scab over and heal. 

Blisters develop in waves. As some start to heal and crust over, new spots can appear. Because of this, some describe the pattern or look of the rash as a “starry sky.”

Other symptoms may be flu-like symptoms such as:

  • A fever
  • Fatigue (really tired)
  • Malaise (feeling unwell)
  • Muscle aches
  • Sore throat, runny nose, cough
  • Headache

Mpox (Monkeypox) vs. Chickenpox

Mpox (formerly referred to as monkeypox) and chickenpox are different viral infections that cause similar symptoms, including a rash that turns into blisters. The following is a comparison of how they differ.

  • Rare

  • Caused by the monkeypox virus

  • Transmitted from animals to people

  • Rash typically stays on the face, arms, and legs

  • Very common and contagious

  • Caused by the varicella-zoster virus

  • Transmitted from person to person

  • Rash is widespread on the body

Stages of Chickenpox: Symptom Progression

Chickenpox has four distinct stages, each has its own set of symptoms. 

Stage 1 (Incubation)

The first stage of chickenpox (incubation) lasts 10 to 21 days. This is when the virus enters the body and starts to spread, but there are no symptoms. 

Stage 2 (Prodromal)

The second (prodromal) stage lasts for one to two days. During this phase, a person may have cold or flu-like symptoms such as a fever, sore throat, headache, loss of appetite, and fatigue. 

Flu-like symptoms are more common in adults than children. The rash is frequently the first symptom for kids.

A person is contagious and can spread the virus to others during this stage. 

Stage 3 (Active)

The third stage is the active stage, when the characteristic chickenpox rash appears. It usually starts as red bumps on the face, chest, and back and then spreads to the rest of the body. 

The rash develops into fluid-filled blisters. After a few days, the sores crust over and eventually fall off. 

While a person is most contagious during this time, they can transmit it during all phases. This stage usually lasts about four to seven days.

Stage 4 (Recovery)

The final stage of chickenpox is the recovery stage. It typically lasts about one to two weeks. As the blisters heal, they can cause itching and discomfort.

Chickenpox and Shingles

The varicella virus causes both chickenpox and shingles, but there are key differences in their presentation. The following summarizes the key differences: 

  • Chickenpox is the primary infection (when a person gets varicella for the first time).
  • After someone has chickenpox, the varicella virus stays dormant in the body.
  • People get shingles when the varicella virus reactivates. 
  • The shingles rash is usually on one side of the body and is more painful than chickenpox.
  • Shingles typically occurs in older adults or people with weakened immune systems. 

How Long Is Chickenpox Contagious?

You're contagious with chickenpox from one to two days before the rash appears until all the blisters have crusted over. You are most contagious during the two days before the rash through the first several days of the rash.

If you have had the vaccine and develop a mild case of chickenpox, you may have sores that don’t crust over. In this case, you are contagious until you have not developed any new sores for 24 hours.

Should You Quarantine With Chickenpox?

Experts recommend quarantining (avoiding contact with others) until all the blisters have crusted over. Because the blisters come in waves, it typically takes 10 to 14 days for this to occur.

Quarantining helps prevent the spread of the virus to others, which is especially important for those at higher risk for complications (pregnant people, newborns, and people with weakened immune systems).

Those with shingles can spread the virus to someone who has not had chickenpox or has not had the vaccine. However, that person will get chickenpox, not shingles.

Avoiding Transmission While Caring for Someone with Chickenpox

When caring for someone with chickenpox, you can take extra precautions to help prevent the spread, including:

  • Washing your hands frequently (for 20 seconds or more)
  • Not scratching (this can break blisters, and the fluid is contagious)
  • Not sharing personal items 
  • Disinfecting surfaces 
  • Getting a postexposure vaccination (if you are not immune)
  • Wearing an N95 mask (especially for those at high risk)

How Is Chickenpox Diagnosed?

Healthcare providers typically diagnose chickenpox by its characteristic symptoms and rash. In some cases, a provider may order the following lab tests to confirm the diagnosis: 

  • Polymerase chain reaction (PCR) test (using a small sample of the fluid in the blister)
  • Blood tests
  • Culture (blister fluid is put in a petri dish in the lab to see what grows)

They may also ask you questions or run tests to rule out other conditions that can cause similar symptoms, including:

Chickenpox Treatment

Chickenpox typically clears up on its own within a few weeks. Most of the time, treatment involves easing the symptoms such as itching and discomfort. 

You can keep the itch down by:

You can also try nonaspirin over-the-counter (OTC) fever and pain medications. The American Academy of Pediatrics recommends Tylenol (acetaminophen) rather than Advil and Motrin (ibuprofen). 

Do Not Give Children Aspirin

Do not give children aspirin unless it is under the direction and supervision of a healthcare provider (this would only occur in rare situations). Aspirin can cause Reye's syndrome in kids. Reye's syndrome is a serious illness that affects the liver and brain.

Healthcare providers may prescribe antiviral medications such as Zovirax (acyclovir) for those with severe cases or weakened immune systems. Antivirals can help reduce the severity, duration, and risk of complications.

Healthcare providers may also suggest varicella-zoster immune globulin infusions for those who can not have the vaccine and are at high risk.

Complications From Chickenpox 

While chickenpox is usually a mild illness in children, it can be more severe for people:

  • Over 12 years old
  • Under 1 year old
  • With weakened immune systems (lower ability to fight germs)
  • Who are pregnant

The most common complications of the varicella virus include bacterial infections and pneumonia.


Children with chickenpox are most at risk for bacterial infections of the skin and soft tissues. They are also susceptible to dehydration.


Adults who get varicella are most at risk of developing pneumonia. Rare but serious complications also include:

  • Cerebellar ataxia (loss of muscle coordination)
  • Encephalitis (brain infection or inflammation)
  • Hemorrhagic (bleeding) conditions
  • Complications of bacterial infections (sepsis, toxic shock syndrome, osteomyelitis)

Pregnant people who get chickenpox are at higher risk of getting pneumonia. If they have varicella in the first trimester or early second trimester, the baby could have congenital abnormalities, including scars, abnormal legs or arms, brain or eye problems, and low birth weight.

Chickenpox Vaccine

In the United States, chickenpox was much more common before the vaccine. About 4 million people got chickenpox in the early 1990s before the vaccine became available in 1995. 

Chickenpox rates decreased by more than 97% in the United States over the past 25 years. The Centers for Disease Control and Prevention (CDC) estimates the chickenpox vaccine has prevented 91 million cases since then.

The CDC recommends two doses of the chickenpox vaccine for those who have not had chickenpox or the vaccine. 

Children typically get their first dose between 12 and 25 months and their second dose between four and six. Second doses can be given earlier, but it needs to be at least three months after the first dose.

Who Else Should Get the Vaccine?

The vaccination is also crucial for:

  • Teachers and childcare workers
  • Healthcare professionals
  • Those who care for people with weak immune systems
  • People who live or work in correctional facilities
  • Those in the military
  • International travelers
  • Teens and adults that live with younger children
  • People who can or may become pregnant

You do not need a vaccination if you already have immunity against varicella, such as if you have already had the disease.


Most people with chickenpox recover fully and avoid serious complications. However, it can cause complications such as pneumonia and bacterial infections in some cases. 

The best way to prevent chickenpox is to get the vaccine.  In the United States, rates have decreased by 97% since the vaccination program began in 1995.

Healthcare providers may suggest antivirals or immunoglobulin infusions to those at high risk and who can not get the vaccination, including babies, pregnant people, and those with weakened immune systems. 

19 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Nemours Kids Health. Chickenpox (for parents).

  2. Centers for Disease Control and Prevention (CDC). Chickenpox (varicella) transmission.

  3. Immunization Action Coalition. Varicella (chickenpox) questions and answers.

  4. Centers for Disease Control and Prevention (CDC). Chickenpox symptoms.

  5. Nemours Kids Health. Chickenpox.

  6. Chickenpox: Overview. In: InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2019.

  7. Centers for Disease Control and Prevention (CDC). About Mpox.

  8. Hussain A, Kaler J, Lau G, et al. Clinical conundrums: Differentiating monkeypox from similarly presenting infections. Cureus. 2022;14(10):e29929. doi:10.7759/cureus.29929

  9. Centers for Disease Control and Prevention (CDC). Chickenpox (varicella) - For healthcare professionals.

  10. Centers for Disease Control and Prevention (CDC). Chickenpox (varicella) prevention and treatment.

  11. How can you avoid getting chickenpox? In: InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2017.

  12. Centers for Disease Control and Prevention (CDC). Chickenpox (varicella) - Interpreting laboratory results.

  13. National Library of Medicine (NIH). Rickettsialpox. MedlinePlus.

  14. Meyer H., Ehmann R, Smith GL. Smallpox in the post-eradication era. Viruses. 2020;12(2). doi:10.3390/v12020138

  15. Tumewu J, Wardiana M, Ervianty E, et al. An adult patient with suspected of monkeypox infection differential diagnosed to chickenpox. Infectious disease reports. 2020;12(Suppl 1):8724. doi:10.4081/idr.2020.8724

  16. National Library of Medicine (NIH). Chickenpox. MedlinePlus.

  17. Centers for Disease Control and Prevention (CDC). Chickenpox (varicella) complications.

  18. Marin M, Seward JF, Gershon AA. 25 years of varicella vaccination in the United States. The Journal of Infectious Diseases. 2022;226(4);S375–S379, doi:10.1093/infdis/jiac251

  19. Centers for Disease Control and Prevention (CDC). Chickenpox vaccination: What everyone should know.

Additional Reading

By Brandi Jones, MSN-ED RN-BC
Brandi is a nurse and the owner of Brandi Jones LLC. She specializes in health and wellness writing including blogs, articles, and education.