Questions & Answers

What causes chickenpox?
Chickenpox is caused by a virus, the varicella-zoster virus.

How does chickenpox spread?
Chickenpox spreads from person to person by direct contact or through the air by coughing or sneezing. It is highly contagious. It can also be spread through direct contact with the fluid from a blister of a person infected with chickenpox, or from direct contact with a sore from a person with shingles.

How long does it take to show signs of chickenpox after being exposed?
It takes from 10–21 days to develop symptoms after being exposed to a person infected with chickenpox. The usual time period is 14–16 days.

What are the symptoms of chickenpox?
The most common symptoms of chickenpox are rash, fever, coughing, fussiness, headache, and loss of appetite. The rash usually develops on the scalp and body, and then spreads to the face, arms, and legs. The rash usually forms 200–500 itchy blisters in several successive crops. The illness lasts about 5–10 days.

How serious is chickenpox?
Many cases of chickenpox are mild, but deaths from this disease can occur. Before the development of a vaccine, about 100 people died every year in the United States from chickenpox. Most of these people were previously healthy. Chickenpox also accounted for about 11,000 hospitalizations each year. Even children with average cases of chickenpox are uncomfortable and need to be kept out of daycare or school for a week or more.

What are possible complications from chickenpox?
The most common complication is bacterial infection of the skin or other parts of the body including the bones, lungs, joints, and blood. The virus can also lead to pneumonia or infection of the brain. These complications are rare but serious. Complications are more common in infants, adults, and people with weakened immune systems.

How do I know if my child has chickenpox?
Usually chickenpox can be diagnosed by disease history and appearance alone. Adults who need to know if they've had chickenpox in the past can have this determined by a laboratory test.

How long is a person with chickenpox contagious?
Patients with chickenpox are contagious for 1–2 days before the rash appears and continue to be contagious through the first 4–5 days or until all the blisters are crusted over.

Is there a treatment for chickenpox?
Most cases of chickenpox in otherwise healthy children are treated with bed rest, fluids, and control of fever. Children with chickenpox should NOT receive aspirin because of possible subsequent risk of Reye's syndrome. Acetaminophen may be given for fever control.

Chickenpox may be treated with an antiviral drug in serious cases, depending on the patient's age and health, the extent of the infection, and the timing of the treatment.

How common is chickenpox in the U.S.?
Because it is so easy to catch chickenpox, almost every adult in the United States has been infected. Until a vaccine became available, there were an estimated four million cases/year. Since the vaccine was licensed in 1995, the number of cases of chickenpox had fallen 83%–93% by 2004.

Can you get chickenpox more than once?
Most people are immune to chickenpox after having the disease. However, although it is not common, second cases of chickenpox can occur, particularly in immunocompromised people.

If I think my child has been exposed to chickenpox, what should I do?
If the child has had chickenpox or has been vaccinated, nothing needs to be done. It is recommended that a susceptible person (one who has never had chickenpox) receive the chickenpox vaccine as soon as possible after being exposed to the virus. There is evidence that the vaccine may prevent illness or reduce the seriousness of the disease, if given within 3 to 5 days following exposure. Even if the person was not infected with the chickenpox virus from the exposure, receiving the vaccination will prevent future disease.

How are chickenpox and shingles related?
Both chickenpox and shingles are caused by the same virus. After a person has had chickenpox, the virus rests in the body permanently, but silently. About 20% of all people who have been infected with chickenpox later develop the disease known as herpes zoster, or shingles. Symptoms of shingles are pain, itching, blisters, and loss of feeling along a nerve. Most cases occur in people older than 50, and the risk of developing shingles increases with age. In May 2006, the FDA approved a zoster vaccine to prevent shingles. Currently, the vaccine is only licensed for people age 60 years and older. (See the shingles section for more information about shingles disease and zoster vaccine.)

Questions and answers about chickenpox (varicella) vaccine

Technically reviewed by the Centers for Disease Control and Prevention, September 2010