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Chicken Pox

Also known as:  Varicella

What is it?

Chicken pox, also called varicella, is an extremely infectious disease that produces an itchy, blistery rash that lasts about a week. A single attack of chicken pox usually provides lifelong immunity against the disease.

Who gets it?

Before the development of the chicken pox vaccine, approximately four million children in the United States contracted the disease each year. Chicken pox can strike at any age, but about 80 to 90 percent of children in the U.S. have had it by age ten. Adults account for less than five percent of all cases, because almost every case of chicken pox provides lifelong immunity to the disease. Adults are much more likely than children to suffer dangerous complications and account for more than half of all chicken pox deaths.

What causes it?

Chicken pox is caused by the varicella-zoster virus, a member of the herpes virus family. The disease is spread through the air or by direct contact with an infected person.

What are the symptoms?

Symptoms of chicken pox include a mild fever and a feeling of unwellness. Within several hours or days, small red spots begin to appear on the scalp, neck and upper half of the body. After 12 to 24 hours, the spots become itch, fluid-filled bumps which continue to appear for the next two to five days. In some cases, the spots may also be found inside the mouth, nose, ears, vagina, or rectum. After the blisters form, scabs develop and fall off. Scarring usually does not occur unless the blisters have been scratched and become infected. Occasionally a minor and temporary darkening of the skin (called hyperpigmentation) develops around some of the blisters.

For most people, chicken pox is no more than a few days of discomfort. However, some people are at risk for developing complications such as bacterial infections of the blisters, pneumonia, dehydration, encephalitis and hepatitis. The risk of complications is much higher among infants less than one year of age and adults.

How is it diagnosed?

Diagnosis is usually made at home or by a doctor over the phone. However, a doctor should be immediately contacted if fever is very high, takes more than four days to disappear, or if the blisters become infected (yellow pus, spreading redness, red streaks). In addition, a doctor should be contacted if the infected person seems nervous or confused, complains of a stiff neck or severe headache, has poor balance or trouble walking, is sensitive to light, is having breathing problems or is coughing a lot, is complaining of chest pain, is vomiting repeatedly, or is having convulsions.

What is the treatment?

Treatment of chicken pox usually takes place in the home unless symptoms are severe. Treatment usually focuses on reducing fever by using acetaminophen or another fever-reducing medication. Applying wet compresses or taking a bath with four to eight ounces of baking soda or one to two cups of oatmeal may reduce the itch. Calamine lotion (and some other kinds of lotions) also helps to reduce itchiness. If the itching becomes severe or interferes with sleep, the doctor may recommend a nonprescription antihistamine called Benadryl.

If mouth blisters make eating or drinking difficult, cold drinks and soft, bland foods may be recommended to ease discomfort. Chicken pox symptoms can also be lessened with an antiviral drug called acyclovir (Zovirax). However, it may only be helpful if started within 24 hours of the appearance of the first sores.

Chicken pox is usually only contagious until all the sores have scabbed over, usually about six to seven days after the sores appear.

Self-care tips

Chicken pox usually runs its course within a week without causing lasting harm. In about 20 percent of the population, usually people 50 and over, the virus never leaves the body and lies dormant in the nerve cells where it can be reactivated years later. The result is shingles (also called herpes zoster), a very painful nerve inflammation, accompanied by a rash, that usually affects the trunk or the face for ten days or more.

A vaccine for chicken pox, called Varivax, is now available and is about 85 percent effective for preventing all cases of chicken pox. The vaccine is now given to all children (with the exception of certain high-risk groups) at 12-18 months of age, preferably when they receive their measles-mumps-rubella vaccine. Vaccination is also recommended for any older child or adult considered susceptible to the disease. A single dose of the vaccine is sufficient for children up to age 12; older children and adults receive a second dose four to eight weeks later. The risks of the vaccine are extremely small, but those interested in getting the vaccine should check with their doctor about potential side affects.


This information has been designed as a comprehensive and quick reference guide written by our health care reviewers.  The health information written by our authors is intended to be a supplement to the care provided by your physician.  It is not intended nor implied to be a substitute for professional medical advice. 

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