Chickenpox (Varicella)
A highly contagious varicella-zoster virus infection that causes an itchy blistering rash and can lead to serious complications.
What causes Chickenpox (Varicella)?
Chickenpox is caused by varicella-zoster virus. It spreads through direct contact with blister fluid and through infectious particles from an infected person’s respiratory tract or skin lesions. After infection, the virus remains latent and can later reactivate as shingles.
Symptoms and what to notice
Fever, tiredness, loss of appetite, and headache may begin before an itchy rash. The rash usually starts on the chest, back, or face, then develops in crops of fluid-filled blisters that eventually crust.
How long can it last?
Symptoms usually begin 10 to 21 days after exposure, most often in 14 to 16 days. The illness typically lasts 4 to 7 days, and most blisters crust within about one week.
How serious is Chickenpox (Varicella)?
Bacterial skin infection, pneumonia, encephalitis, bleeding problems, dehydration, and sepsis can occur. Risk is higher in infants, adolescents, adults, pregnant people, and people with weakened immune systems.
Treatment and management
Many healthy children need supportive care for fluids, fever, and itching. Never give aspirin to a child or teenager with chickenpox. Antivirals such as acyclovir or valacyclovir may be used early in higher-risk patients, while severe disease may require intravenous acyclovir and hospital care.
Vaccine: who and when?
Products: VARIVAX is a stand-alone live varicella vaccine licensed for eligible people age 12 months and older. ProQuad is a combined MMRV vaccine licensed for children ages 12 months through 12 years. CDC recommends two childhood doses at ages 12-15 months and 4-6 years. People age 13 or older without immunity need two VARIVAX doses at least 28 days apart. These live vaccines are contraindicated during pregnancy and in certain people with severe immunodeficiency.
Cost note: Patient cost varies by product, provider, insurance, and eligibility. U.S. routine vaccines are commonly covered without cost sharing when given by an in-network provider, and eligible children can receive vaccines through the Vaccines for Children program.
Trusted source
Patient cost varies by insurance, provider, location, and eligibility. Coverage and public-health access differ, so listed prices are examples rather than guaranteed patient prices. This page is for general education and does not replace individualized medical advice, diagnosis, vaccination assessment, or treatment.
Chickenpox (Varicella): Causes, Symptoms, Transmission, Treatment, Prevention, and Vaccine Information
Chickenpox, also called varicella, is a highly contagious illness caused by the varicella-zoster virus (VZV). It is best known for an itchy rash that develops into fluid-filled blisters and then scabs. Before routine vaccination, chickenpox was an extremely common childhood infection in the United States. Vaccination has made the disease, its complications, and related hospitalizations much less common.
Many infections are mild, especially in otherwise healthy children, but chickenpox should not be dismissed as harmless. It can cause bacterial skin infections, pneumonia, inflammation of the brain, bloodstream infection, dehydration, and other serious complications. The risk is greater in infants, adolescents, adults, pregnant people, and people with weakened immune systems.
The same virus can cause two different illnesses. A person’s first VZV infection causes chickenpox. After recovery, the virus remains inactive in nerve tissue and may reactivate years later as shingles, also called herpes zoster. Chickenpox and shingles are therefore related, but they are not the same clinical illness.
Quick Facts
- Cause: Varicella-zoster virus.
- Spread: Mainly through direct contact with blister fluid and through virus-containing particles from an infected person’s respiratory tract or skin lesions.
- Incubation period: Usually 14 to 16 days after exposure, with a possible range of 10 to 21 days.
- Contagious period: Usually from 1 to 2 days before the rash appears until every lesion has crusted. A vaccinated person whose lesions do not crust is considered contagious until no new lesions have appeared for 24 hours.
- Typical illness duration: The rash and other symptoms usually last about 4 to 7 days, although scabs and skin marks may take longer to resolve.
- Vaccine availability: Yes. The U.S.-licensed products are VARIVAX, a stand-alone varicella vaccine, and ProQuad, a combined measles, mumps, rubella, and varicella vaccine for eligible children.
- Emergency warning signs: Trouble breathing, severe weakness, confusion, difficulty waking, a stiff neck, repeated vomiting, poor fluid intake, signs of dehydration, or a rash that becomes very red, warm, painful, or drains pus.
What Causes Chickenpox?
Chickenpox is caused by varicella-zoster virus, a member of the herpesvirus family. Infection begins after the virus enters the body, commonly through the respiratory tract or direct contact with virus from skin lesions. It then multiplies and spreads through the body before the characteristic rash appears.
After the immune system controls the initial infection, VZV does not leave the body completely. It becomes latent in sensory nerve tissue. If it reactivates later, it causes shingles rather than a second typical episode of chickenpox. Shingles can occur in anyone who has previously had chickenpox, although the risk rises with age and immune suppression.
Chickenpox is not caused by poor hygiene, food, or exposure to cold weather. Because it is highly contagious, infection can spread quickly among people who are not immune, particularly in households, schools, childcare settings, and other places with close contact.
How Chickenpox Spreads
VZV spreads easily from a person who has chickenpox. Transmission can occur when another person inhales infectious particles or has direct contact with fluid from the blisters. A person without immunity can also develop chickenpox after exposure to someone with shingles, because shingles lesions contain VZV. In that situation, the exposed person develops chickenpox, not shingles.
According to the CDC, approximately 90% of susceptible close contacts become infected after household exposure. The virus can spread before an infected person realizes that the rash is about to begin, which makes prevention by isolation alone difficult.
A person with chickenpox is generally contagious from 1 to 2 days before the rash appears until all lesions have crusted. This often takes about a week. Some vaccinated people develop a milder form called breakthrough varicella in which lesions may remain flat or never crust. They are considered contagious until no new lesions have appeared for 24 hours.
People with chickenpox should avoid contact with anyone who is pregnant and lacks evidence of immunity, newborns, premature infants, and people with weakened immune systems. They should also stay home from school, childcare, work, and group activities until they are no longer contagious, following the advice of a clinician and applicable public-health or school policies.
Incubation Period and Stages
The incubation period is the time between exposure and the start of symptoms. For chickenpox it is usually 14 to 16 days, but it can range from 10 to 21 days. A person generally feels well during most of this period.
The illness often progresses through several stages:
- Prodrome: Fever, tiredness, loss of appetite, or headache may begin 1 to 2 days before the rash. These early symptoms are often more noticeable in adolescents and adults.
- Early rash: Small red spots or bumps usually appear first on the chest, back, or face and then spread over the body. Lesions can also develop inside the mouth, on the eyelids, or in the genital area.
- Blister stage: The bumps become intensely itchy, fluid-filled blisters. New groups of lesions may continue to appear for several days, so spots, blisters, and scabs can be present at the same time.
- Crusting stage: The blisters break or dry and form scabs. The person remains contagious until every lesion has crusted, unless the lesions never crust, in which case the 24-hour no-new-lesion rule applies.
Scratching can break the skin and allow bacteria to enter. Keeping fingernails short, discouraging scratching, and using clinician-approved itch-relief measures can reduce skin injury.
Symptoms
The classic symptom is a generalized itchy rash that progresses from spots to blisters and then scabs. Other symptoms can include:
- Fever
- Tiredness or a general unwell feeling
- Loss of appetite
- Headache
- Itching that may be intense
- Sore areas in the mouth if lesions develop there
Not everyone has the same number of lesions. An unvaccinated person may develop hundreds of spots, while vaccinated people who experience breakthrough disease often have fewer lesions, little or no fever, and a shorter illness.
Symptoms may be more severe in adults than in children. Adults have a higher risk of varicella pneumonia, and people with weakened immune systems may develop prolonged illness or virus spread to internal organs.
How Long Does Chickenpox Last?
The active illness usually lasts 4 to 7 days. New lesions may appear for several days, and most blisters then dry and crust within about a week. Scabs can remain longer and eventually fall off as the skin heals.
The timeline can differ in vaccinated people, infants, adults, and people with weakened immunity. Breakthrough varicella is often shorter and milder. Severe infection can last longer and may require hospitalization. Skin discoloration after a lesion heals may persist temporarily; deeper scarring is more likely when lesions are scratched or become infected.
Because the incubation period can extend to 21 days, a person exposed to chickenpox may need to watch for symptoms for three weeks. Public-health authorities or clinicians may give different monitoring or exclusion instructions for healthcare, school, or high-risk settings.
Breakthrough Chickenpox After Vaccination
No vaccine prevents every infection. Breakthrough varicella is chickenpox that occurs in a vaccinated person more than 42 days after vaccination. It is generally milder than disease in an unvaccinated person.
A vaccinated person may have fewer than 50 lesions, a low fever or no fever, and spots that stay flat instead of becoming typical blisters. Because this rash can resemble insect bites or other skin conditions, breakthrough disease can be harder to recognize. It can still spread to other people, so suspected cases should be assessed and managed carefully.
Two doses of varicella vaccine provide stronger protection than one. The CDC reports that two doses are about 90% effective at preventing chickenpox. Vaccinated people who do become infected are less likely to develop severe illness.
Possible Complications
Most healthy children recover without major problems, but complications can occur. They include:
- Bacterial infection of the skin and soft tissues
- Pneumonia
- Inflammation of the brain, called encephalitis
- Problems with balance and coordination, called cerebellar ataxia
- Dehydration
- Bleeding problems
- Bloodstream infection or sepsis
- Rare involvement of other organs
Seek urgent medical care if a person with suspected chickenpox has difficulty breathing, severe coughing, blue or gray lips, confusion, extreme drowsiness, a stiff neck, difficulty walking, repeated vomiting, severe abdominal pain, dehydration, or a rash that becomes hot, swollen, very painful, or drains pus.
Who Is at Higher Risk?
People at increased risk of serious chickenpox include:
- Infants, especially certain premature infants and newborns exposed around delivery
- Adolescents and adults without immunity
- Pregnant people without evidence of immunity
- People with weakened immune systems because of cancer, HIV, transplantation, immune-suppressing medicine, or high-dose steroid therapy
- People with some chronic skin or lung conditions
Anyone in a high-risk group who has been exposed or develops compatible symptoms should contact a healthcare professional promptly. Do not wait for a severe rash to appear before seeking advice, because post-exposure prevention and antiviral treatment are time-sensitive.
Chickenpox During Pregnancy and Around Birth
Chickenpox during pregnancy requires urgent medical guidance. Pregnant people are at increased risk of severe illness, especially pneumonia. Infection during the first or early second trimester carries a small risk of congenital varicella syndrome, which can affect a developing baby’s skin, limbs, eyes, brain, and other organs. The CDC estimates this risk at approximately 0.4% to 2% after infection during that period.
The period around delivery is also important. A newborn is at risk of severe neonatal varicella if the pregnant parent develops a rash from 5 days before delivery through 2 days after delivery. Obstetric, infectious-disease, pediatric, and public-health specialists may need to coordinate care.
Varicella vaccine is a live vaccine and is not given during pregnancy. A person who lacks immunity can discuss vaccination after pregnancy. Anyone who is pregnant and believes they were exposed should contact their obstetric clinician immediately rather than waiting for symptoms.
Diagnosis and Testing
Clinicians can often suspect chickenpox from the appearance and evolution of the rash, exposure history, vaccination history, and accompanying symptoms. Laboratory confirmation may be important when the rash is atypical, when a vaccinated person has possible breakthrough disease, during outbreaks, or when the diagnosis affects a high-risk patient.
Polymerase chain reaction, or PCR, testing of material from skin lesions is the preferred laboratory method for confirming VZV infection. Samples can be collected from vesicle fluid, scabs, or cells from the base of a lesion. Blood antibody tests have limitations for diagnosing an active rash and should be interpreted in context.
Because several infections, allergic reactions, medication eruptions, and insect bites can resemble chickenpox, avoid relying on photographs or self-diagnosis alone when the diagnosis is uncertain.
Treatment and Home Care
Treatment depends on age, illness severity, time since the rash began, pregnancy status, immune function, and risk of complications. Many otherwise healthy children need supportive care only. Helpful measures may include:
- Rest and adequate fluids
- Lukewarm baths and other gentle measures to reduce itching
- Calamine lotion or clinician-recommended anti-itch medication
- Keeping fingernails clean and short
- Loose clothing to reduce irritation
- Clinician-approved medicine for fever or discomfort
Do not give aspirin to a child or teenager with chickenpox. Aspirin use during viral illness is associated with Reye syndrome, a rare but dangerous condition affecting the liver and brain. The American Academy of Pediatrics also recommends avoiding ibuprofen when possible in children with chickenpox because of an association with serious bacterial skin infections. Ask a clinician which fever or pain medicine is appropriate.
Antiviral Medicine
Antiviral medicine may be recommended for people at increased risk of moderate or severe disease. Options used in appropriate patients include acyclovir and valacyclovir. Oral treatment works best when started early, preferably within the first 24 hours after the rash begins. Treatment decisions should be made by a clinician because age, pregnancy, kidney function, immune status, and illness severity affect the choice and dose.
Intravenous acyclovir is recommended for severe disease, including disseminated infection, pneumonia, encephalitis, or other serious complications, and for some immunocompromised patients. People with severe illness may also need oxygen, intravenous fluids, antibiotics for a secondary bacterial infection, or intensive monitoring.
What to Do After Exposure
After a significant exposure, first determine whether the exposed person has evidence of immunity. Evidence may include age-appropriate vaccination, laboratory evidence of immunity or disease, clinician-verified prior chickenpox or shingles, or other criteria used by the CDC.
For an eligible person without immunity, varicella vaccine given soon after exposure can prevent disease or make it milder. CDC guidance generally recommends vaccination within 3 to 5 days after exposure when vaccination is appropriate, while still offering the vaccine later for protection against future exposures.
Some people at high risk for severe disease cannot receive a live vaccine. They may be eligible for varicella-zoster immune globulin. The U.S. product is VariZIG. It should be given as soon as possible after exposure and can be administered within 10 days. VariZIG provides temporary antibodies; it is not a vaccine and does not create the same long-term immune memory as vaccination.
Contact a healthcare professional or public-health department promptly after exposure if the exposed person is pregnant, immunocompromised, a newborn, certain premature infants, or otherwise unable to receive the vaccine.
Chickenpox Vaccines Available in the United States
The United States has two licensed vaccine products that protect against varicella:
VARIVAX
VARIVAX is a stand-alone live attenuated varicella vaccine. Its proper name is Varicella Virus Vaccine Live. It is licensed for people age 12 months and older who are eligible for vaccination.
ProQuad
ProQuad is a combined live vaccine against measles, mumps, rubella, and varicella, commonly abbreviated MMRV. Its proper name is Measles, Mumps, Rubella and Varicella Virus Vaccine Live. It is licensed for children ages 12 months through 12 years.
ProQuad is not used for adolescents or adults. A clinician chooses between separate MMR plus varicella vaccines and the combined MMRV product based on age, dose number, medical history, benefits, and risks.
Routine Vaccine Schedule
CDC recommends two doses of varicella-containing vaccine for children:
- First dose: 12 through 15 months of age.
- Second dose: 4 through 6 years of age.
Children can receive the second dose earlier if the minimum interval for the selected product and age is met. Catch-up vaccination is recommended for children, adolescents, and adults without evidence of immunity.
People age 13 years or older without evidence of immunity should receive two doses of single-antigen varicella vaccine at least 28 days apart. Adults with a higher likelihood of exposure or transmission—such as healthcare personnel, teachers, childcare workers, college students, international travelers, and household contacts of immunocompromised people—should make sure they have evidence of immunity.
Vaccine schedules can change, and individual circumstances matter. A clinician should confirm the correct product, timing, and interval.
Who Should Not Receive a Varicella Vaccine?
Because varicella vaccines are live vaccines, they are not appropriate for everyone. People should tell the vaccinating clinician about pregnancy, immune-system problems, cancer treatment, recent blood products, medicines that suppress immunity, severe allergies, recent vaccines, or current illness.
Varicella vaccine is contraindicated during pregnancy. It is also contraindicated in certain people with severe immunodeficiency and in anyone with a severe allergic reaction to a previous dose or vaccine component. Some people with less severe immune-system conditions may be vaccinated under specialist guidance.
A moderate or severe acute illness may be a reason to delay vaccination, while a mild illness usually is not. People who recently received blood, plasma, or immune globulin may need to wait because antibodies can interfere with the vaccine response.
Vaccine Side Effects and Safety
Common reactions are usually mild and temporary. They can include:
- Soreness, redness, or swelling where the shot was given
- Fever
- A mild rash or a small number of spots
Serious reactions are rare. A person who develops signs of a severe allergic reaction—such as hives, facial or throat swelling, difficulty breathing, a fast heartbeat, dizziness, or weakness—needs emergency care. Any concerning event after vaccination should be evaluated by a healthcare professional.
Vaccination is safer than acquiring chickenpox naturally. Natural infection carries risks of hospitalization, pneumonia, brain inflammation, severe skin infection, and death, and it leaves the virus in the body where it can later reactivate as shingles.
Prevention Beyond Vaccination
Vaccination is the best way to prevent chickenpox. Additional steps can reduce spread:
- Keep an infected person away from school, childcare, work, and public activities until no longer contagious.
- Avoid contact with pregnant people without immunity, newborns, and immunocompromised people.
- Do not share towels, clothing, bedding, or personal items that may have contacted lesions.
- Wash hands regularly, especially after contact with the infected person or their belongings.
- Cover coughs and sneezes and improve ventilation where practical.
- Keep lesions clean and discourage scratching.
- Follow healthcare or public-health guidance during an outbreak.
Household prevention can be difficult because contagiousness begins before the rash. Check immunity and seek post-exposure advice promptly rather than relying only on separation after symptoms begin.
Chickenpox and Shingles
Chickenpox and shingles are both caused by VZV. Chickenpox is the primary infection; shingles is a reactivation of latent virus. A person cannot catch shingles from someone else, but a person without VZV immunity can catch the virus from shingles lesions and develop chickenpox.
The childhood varicella vaccine and the adult shingles vaccine have different purposes, products, age recommendations, and schedules. A shingles vaccine does not replace routine varicella vaccination for someone who lacks evidence of immunity, and varicella vaccine is not the routine shingles vaccine for older adults. Ask a clinician which vaccine is appropriate.
When to Contact a Healthcare Professional
Contact a clinician promptly if chickenpox is suspected in a person who is pregnant, younger than one year, older than 12 years and not immune, immunocompromised, or taking immune-suppressing medicine. Also call if fever persists or returns, the rash becomes increasingly painful or infected, symptoms worsen, or the diagnosis is uncertain.
Seek emergency care for breathing difficulty, confusion, inability to wake normally, a stiff neck, trouble walking, repeated vomiting, severe dehydration, a rapidly worsening rash, or other signs of severe illness.
Before visiting a clinic, call ahead and explain that chickenpox is possible. The facility may use special arrival and isolation procedures to protect other patients.
Frequently Asked Questions
Can a vaccinated person still get chickenpox?
Yes. Breakthrough varicella can occur, but it is usually milder and shorter than illness in an unvaccinated person. Two doses provide better protection than one.
Can someone get chickenpox twice?
Most people develop lasting immunity after infection, so a second episode is uncommon. A later VZV illness is more often shingles. Laboratory testing may be needed when the history or rash is uncertain.
Is there a vaccine for chickenpox?
Yes. VARIVAX is the stand-alone U.S. varicella vaccine for eligible people age 12 months and older. ProQuad is the combined MMRV vaccine for eligible children ages 12 months through 12 years.
How soon after exposure should vaccination be given?
For an eligible person without immunity, vaccination is most helpful when given within 3 to 5 days after exposure. It may still be offered later to protect against future exposure.
What is VariZIG?
VariZIG is varicella-zoster immune globulin used after exposure for certain high-risk people who cannot receive varicella vaccine. It supplies temporary antibodies and is not a vaccine.
When can a child return to school?
Generally, when all lesions have crusted. If a vaccinated child has lesions that do not crust, the CDC uses no new lesions for 24 hours as the contagious-period endpoint. Follow the child’s clinician and local school or public-health rules.
Can chickenpox be treated with antibiotics?
Antibiotics do not treat VZV. They may be needed only if a bacterial complication develops. Antiviral medicines such as acyclovir or valacyclovir may be used for selected patients.
Should aspirin be used for fever?
No. Children and teenagers with chickenpox should not receive aspirin because of the risk of Reye syndrome. Ask a clinician about safe alternatives.
Key Takeaways
Chickenpox is a highly contagious VZV infection with a characteristic itchy blistering rash. Illness usually lasts 4 to 7 days, but the virus can spread before the rash begins and until all lesions have crusted. Complications are possible, especially in infants, adults, pregnant people, and people with weakened immunity.
The U.S. vaccines are VARIVAX and, for eligible children, ProQuad. CDC recommends a two-dose childhood schedule and catch-up vaccination for people without evidence of immunity. Prompt medical advice is important after high-risk exposure, during pregnancy, or when severe symptoms develop.
Official Sources
- CDC: Clinical Overview of Chickenpox
- CDC: Chickenpox Signs and Symptoms
- CDC: Chickenpox Treatment
- CDC: Clinical Guidance for People at Risk for Severe Varicella
- CDC: Chickenpox Vaccination
- FDA: VARIVAX
- FDA: ProQuad
Medical guidance and vaccine recommendations reviewed through September 2026. Recommendations may change. Use current CDC guidance and individualized advice from a qualified healthcare professional.