Symptoms

The first symptoms of chickenpox include:

• A fever of 100.4°F (38°C) to 103°F (39.4°C).
• Feeling sick, tired, and sluggish.
• Little or no appetite.
• Headache and sore throat.

The first symptoms are usually mild in children, but they can be severe in teens and adults. These symptoms may continue throughout the illness.

About 1 or 2 days after the first symptoms of chickenpox appear, an itchy rash develops. During a typical course of chickenpox:

• Red or swollen spots or bumps appear and turn into blisters that are filled with clear or cloudy fluid and that look like pimples.
• The blisters break open, often leaking fluid.
• A dry crust forms over the broken blisters as they heal.

Chickenpox is most contagious from 2 to 3 days before the rash appears until all the blisters have crusted over.

Other conditions may cause a similar rash.

What Happens

The first symptoms of chickenpox—fever, feeling sick, decreased appetite, headache, cough, and sore throat—usually develop between 14 and 16 days after contact with a person infected with the virus. But it may be as late as 21 days after contact before symptoms appear.

• Some children develop the chickenpox rash without first having the early symptoms.
• Babies 6 months old and younger may have some protection against chickenpox from antibodies passed on by their mothers. So if they are infected with the virus, they may not have many symptoms.
• People with impaired immune systems may develop the first symptoms of chickenpox sooner than the usual 10 to 14 days after exposure.

Chickenpox rash usually appears on the upper body about 1 or 2 days after the first symptoms develop. The trunk usually is most affected, the arms and legs the least. The rash also may spread to the scalp, face, nose, and mouth. In rare cases, it spreads into the eyelid lining (conjunctiva), into the clear covering over the eye (cornea), inside the throat, or into the genital area.

It takes about 1 or 2 days for a chickenpox red spot (macule) to go through all its stages, including drying and crusting over. New red spots continue to develop every day for as long as 5 to 7 days.

Skin infection is the most common complication for children under age 5. Skin infection can develop after scratching the rash, which allows bacteria from the skin or under the fingernails to get into a chickenpox blister. This condition can become serious if it is not treated. An infected blister also may develop into a scar.

Some people may have more chickenpox blisters and longer-lasting symptoms than healthy children. Severe illness or complications are more common in:

• Infants after infection of the mother. A baby born within a few days of his or her mother's chickenpox infection has a risk of severe chickenpox infection. Babies born to women who had chickenpox in the first or early second trimester of pregnancy may develop congenital varicella syndrome, which can cause birth defects such as eye problems or an underdeveloped limb.
• Pregnant women, who are at risk for premature labor and varicella pneumonia.
• People age 13 and older (especially people who smoke cigarettes or have long-term lung diseases).
• People who have impaired immune systems.
• People who have cystic fibrosis, which causes problems with the lungs and other organs.
• Children and adolescents receiving long-term aspirin therapy.

The varicella-zoster virus that causes chickenpox can appear in different forms. These variations of chickenpox are most often seen in young children and in the fetus of a pregnant woman.

Although you become immune to the chickenpox virus after you have had chickenpox, the virus will still be in your body. The virus can later cause shingles (herpes zoster), usually when you are an older adult. About 20 out of 100 people who have chickenpox will later develop shingles.¹