The itchy blister rash caused by chickenpox infection appears 10 to 21 days after exposure to the virus and usually lasts about five to 10 days. Other signs and symptoms, which may appear one to two days before the rash, include:

• Fever
• Loss of appetite
• Headache
• Tiredness and a general feeling of being unwell (malaise)

Once the chickenpox rash appears, it goes through three phases:

• Raised pink or red bumps (papules), which break out over several days
• Small fluid-filled blisters (vesicles), which form in about one day and then break and leak
• Crusts and scabs, which cover the broken blisters and take several more days to heal

New bumps continue to appear for several days, so you may have all three stages of the rash — bumps, blisters and scabbed lesions — at the same time. You can spread the virus to other people for up to 48 hours before the rash appears, and the virus remains contagious until all broken blisters have crusted over.

The disease is generally mild in healthy children. In severe cases, the rash can cover the entire body, and lesions may form in the throat, eyes, and mucous membranes of the urethra, anus and vagina.

Chickenpox infection is caused by a virus. It can spread through direct contact with the rash. It can also spread when a person with the chickenpox coughs or sneezes and you inhale the air droplets.

Your risk of becoming infected with the varicella-zoster virus that causes chickenpox is higher if you haven't already had chickenpox or if you haven't had the chickenpox vaccine. It's especially important for people who work in child care or school settings to be vaccinated.

Most people who have had chickenpox or have been vaccinated against chickenpox are immune to chickenpox. If you've been vaccinated and still get chickenpox, symptoms are often milder, with fewer blisters and mild or no fever. A few people can get chickenpox more than once, but this is rare.

Chickenpox is normally a mild disease. But it can be serious and can lead to complications including:

• Bacterial infections of the skin, soft tissues, bones, joints or bloodstream (sepsis)
• Dehydration
• Pneumonia
• Inflammation of the brain (encephalitis)
• Toxic shock syndrome
• Reye's syndrome in children and teenagers who take aspirin during chickenpox
• Death

Chickenpox and pregnancy

Low birth weight and limb abnormalities are more common among babies born to women who are infected with chickenpox early in their pregnancy. When a mother is infected with chickenpox in the week before birth or within a couple of days after giving birth, her baby has a higher risk of developing a serious, life-threatening infection.

If you're pregnant and not immune to chickenpox, talk to your doctor about the risks to you and your unborn child.

Chickenpox and shingles

If you've had chickenpox, you're at risk of a complication called shingles. The varicella-zoster virus remains in your nerve cells after the skin infection has healed. Many years later, the virus can reactivate and resurface as shingles — a painful cluster of short-lived blisters. The virus is more likely to reappear in older adults and people who have weakened immune systems.

The pain of shingles can persist long after the blisters disappear. This is called postherpetic neuralgia and can be severe.

Two shingles vaccines (Zostavax and Shingrix) are available for adults who have had chickenpox. Shingrix is approved and recommended for people age 50 and older, including those who've previously received Zostavax. Zostavax isn't recommended until age 60. Shingrix is preferred over Zostavax.