Chickenpox is a viral infection that causes a distinctive rash, fever, and body aches

Chickenpox is caused by the varicella-zoster virus. The infection spreads through the air when an infected person coughs or sneezes, or through direct contact with the characteristic fluid-filled blisters that appear on the skin. Most people who get chickenpox develop immunity to the virus for life, though the virus remains dormant in nerve tissue and can reactivate later as shingles.

The disease typically lasts 7 to 10 days from the time symptoms start. It is most common in children, though adults and vaccinated people can still contract it. Severity varies widely — some people have mild symptoms while others develop complications that require medical attention.

Key Takeaways

  • Chickenpox spreads through respiratory droplets or direct contact with blisters and is contagious from one to two days before the rash appears until all blisters have crusted over.
  • The infection causes fever, fatigue, and loss of appetite followed by a rash that progresses from red spots to fluid-filled blisters to crusted scabs over several days.
  • Most people recover without treatment, but complications like bacterial skin infections, pneumonia, and encephalitis can occur, particularly in adults and immunocompromised individuals.
  • The varicella vaccine prevents chickenpox in most people who receive it and significantly reduces severity if infection does occur.

How the infection develops and what symptoms look like

Chickenpox has an incubation period of 10 to 21 days after exposure to the virus. This means a person can be infected and contagious before they feel sick or notice any signs. The first symptoms are usually non-specific: fever, headache, body aches, fatigue, and loss of appetite. These early symptoms may last one to two days.

The rash appears next, typically starting on the face, scalp, or chest and spreading to other parts of the body. The rash progresses through three stages over several days. It begins as flat red spots, then develops into raised bumps, and finally becomes fluid-filled blisters. As the blisters dry out, they crust over and eventually fall off, leaving temporary pink marks that fade over weeks. New blisters can continue to appear for three to four days, so a person may have spots in all three stages at the same time.

The itching is often intense and can last throughout the illness. Scratching the blisters increases the risk of bacterial infection and can lead to permanent scarring.

Who is most at risk for serious complications

Most children recover from chickenpox without lasting effects. However, certain groups face higher risk of complications. Adults who contract chickenpox are more likely to develop pneumonia, encephalitis (brain inflammation), or severe skin infections than children are. Pregnant people, particularly in the first or third trimester, can experience serious complications and may pass the virus to the fetus.

People with weakened immune systems — including those with HIV, those undergoing chemotherapy, or those taking immunosuppressant medications — are at elevated risk for severe disease and complications. Newborns whose mothers did not have chickenpox immunity and infants too young to be vaccinated are also vulnerable to severe infection.

Secondary bacterial infections of the blisters are common, especially when blisters are scratched. These can lead to abscesses, cellulitis, or in rare cases, invasive streptococcal or staphylococcal infection. Pneumonia, though uncommon in healthy children, occurs more frequently in adults and immunocompromised individuals.

Treatment focuses on managing symptoms while the body fights the virus

There is no cure for chickenpox, but treatment aims to reduce fever, ease itching, and prevent complications. Over-the-counter fever reducers like acetaminophen or ibuprofen can lower fever and body aches. Lukewarm baths with colloidal oatmeal or baking soda can soothe itching. Keeping fingernails short and wearing soft clothing reduces the urge and ability to scratch.

Antiviral medications like acyclovir may be prescribed for adults, immunocompromised individuals, or people at high risk of complications. These medications work best when started early in the infection and can reduce symptom severity and duration. Most healthy children do not need antiviral treatment.

A person with chickenpox should stay home and avoid contact with others until all blisters have crusted over, which typically takes 7 to 10 days. This prevents spreading the virus to people who have not had chickenpox or the vaccine.

Prevention through vaccination is highly effective

The varicella vaccine prevents chickenpox in approximately 90 percent of vaccinated people. Among those who do contract chickenpox after vaccination, the infection is usually much milder, with fewer blisters, lower fever, and faster recovery. The vaccine is given in two doses: the first at 12 to 15 months of age and the second at 4 to 6 years old.

Adults who have never had chickenpox or the vaccine can receive the vaccine at any age. Two doses given 4 to 6 weeks apart provide protection. People who are unsure whether they have had chickenpox can ask their doctor about a blood test to check for immunity before deciding whether to vaccinate.

The vaccine is not recommended for pregnant people, but vaccination before pregnancy is safe and effective. People with certain medical conditions or taking specific medications should discuss vaccination with their doctor to determine whether it is appropriate for them.

Shingles can develop years or decades after chickenpox

After a person recovers from chickenpox, the varicella-zoster virus remains dormant in nerve cells. In some people, the virus reactivates later in life as shingles (herpes zoster). Shingles causes a painful rash, usually on one side of the body, and can lead to long-term nerve pain called postherpetic neuralgia.

The risk of shingles increases with age and is higher in people with weakened immune systems. A person cannot catch shingles from another person, but someone with shingles can transmit the varicella-zoster virus to people who have never had chickenpox or the vaccine, causing chickenpox in those individuals.

A separate vaccine called the shingles vaccine (recombinant zoster vaccine) is recommended for adults 50 and older to prevent shingles or reduce its severity. This vaccine is different from the chickenpox vaccine and provides protection against reactivation of the dormant virus.

When to contact a doctor

Most people with chickenpox do not need to see a doctor. However, contact a healthcare provider if fever lasts more than four days or exceeds 103°F (39.4°C), if blisters show signs of bacterial infection (increasing redness, warmth, pus, or spreading), if breathing becomes difficult, if there is severe headache or stiff neck, or if confusion or extreme drowsiness develops.

People in high-risk groups — adults, pregnant people, immunocompromised individuals, and newborns — should contact a doctor as soon as chickenpox is suspected, as antiviral treatment may be recommended. Do not wait for complications to develop.

If you are unsure whether symptoms are chickenpox or another condition, a doctor can confirm the diagnosis through examination or, if needed, a blood test or culture of fluid from a blister.

Frequently Asked Questions

Can someone get chickenpox twice?

Reinfection is rare but possible. Most people who recover from chickenpox develop lifelong immunity. However, vaccinated people or those with weakened immune systems may contract chickenpox more than once, though the second infection is usually milder than the first.

Is chickenpox dangerous during pregnancy?

Chickenpox during pregnancy carries risks to both mother and fetus. Infection in the first 20 weeks can cause congenital varicella syndrome, which may result in birth defects. Infection close to delivery can cause severe chickenpox in the newborn. Pregnant people should contact their doctor immediately if exposed to or infected with chickenpox.

How long does immunity from the vaccine last?

Immunity from the varicella vaccine is long-lasting, and most vaccinated people remain protected throughout their lives. Booster doses are not routinely recommended for healthy people. Immunity can be checked with a blood test if there is doubt about protection.

Can adults who had chickenpox as children still get shingles?

Yes. Anyone who has had chickenpox carries the dormant virus and can develop shingles later in life. The risk increases after age 50. The shingles vaccine is recommended for adults 50 and older to prevent reactivation or reduce severity if it occurs.

What should I do if I think I have been exposed to chickenpox?

If you have never had chickenpox or the vaccine and believe you have been exposed, contact your doctor within 3 to 5 days. Antiviral medication given early may prevent infection or reduce severity. If you are vaccinated or immune, no action is needed. If you are pregnant or immunocompromised, seek medical advice immediately.