Overview

Chickenpox is an infection caused by the varicella-zoster virus. It causes an itchy rash with small, fluid-filled blisters. Chickenpox is highly contagious to people who haven't had the disease or been vaccinated against it. Today, a vaccine is available that protects children against chickenpox. Routine vaccination is recommended by the U.S. Centers for Disease Control and Prevention (CDC).

The chickenpox vaccine is a safe, effective way to prevent chickenpox and its possible complications.

Symptoms

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.

When to see a doctor

If you think you or your child might have chickenpox, consult your doctor. He or she usually can diagnose chickenpox by examining the rash and considering other symptoms. Your doctor can also prescribe medications to lessen the severity of chickenpox and treat complications, if necessary. To avoid infecting others in the waiting room, call ahead for an appointment and mention that you think you or your child may have chickenpox.

Also, let your doctor know if:

• The rash spreads to one or both eyes.
• The rash gets very red, warm or tender. This could indicate a secondary bacterial skin infection.
• The rash is accompanied by dizziness, disorientation, rapid heartbeat, shortness of breath, tremors, loss of muscle coordination, worsening cough, vomiting, stiff neck or a fever higher than 102 F (38.9 C).
• Anyone in the household has a problem with his or her immune system or is younger than 6 months.

Causes

Chickenpox infection is caused by the varicella-zoster 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.

Risk factors

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

Complications

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

Who's at risk?

People who are at higher risk of chickenpox complications include:

• Newborns and infants whose mothers never had chickenpox or the vaccine
• Adolescents and adults
• Pregnant women who haven't had chickenpox
• People who smoke
• People whose immune systems are weakened by medication, such as chemotherapy, or by a disease, such as cancer or HIV
• People who are taking steroid medications for another disease or condition, such as asthma

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 last long after the blisters disappear. This is called postherpetic neuralgia and can be severe.

The shingles vaccine (Shingrix) is recommended for adults who have had chickenpox. Shingrix is approved and recommended for people age 50 and older, including those who've previously received another shingles vaccine (Zostavax). Zostavax, which isn't recommended until age 60, is no longer sold in the United States.

Prevention

The chickenpox (varicella) vaccine is the best way to prevent chickenpox. Experts from the CDC estimate that the vaccine provides complete protection from the virus for nearly 98% of people who receive both of the recommended doses. When the vaccine doesn't provide complete protection, it significantly lessens the severity of chickenpox.

The chickenpox vaccine (Varivax) is recommended for:

• Young children. In the United States, children receive two doses of the varicella vaccine — the first between ages 12 and 15 months and the second between ages 4 and 6 years — as part of the routine childhood vaccination schedule.

  The vaccine can be combined with the measles, mumps and rubella vaccine, but for some children between the ages of 12 and 23 months, the combination may increase the risk of fever and seizure from the vaccine. Discuss the pros and cons of combining the vaccines with your child's doctor.

• Unvaccinated older children. Children ages 7 to 12 years who haven't been vaccinated should receive two catch-up doses of the varicella vaccine, given at least three months apart. Children age 13 or older who haven't been vaccinated should also receive two catch-up doses of the vaccine, given at least four weeks apart.

• Unvaccinated adults who've never had chickenpox and are at high risk of exposure. This includes health care workers, teachers, child care employees, international travelers, military personnel, adults who live with young children and all women of childbearing age.

  Adults who've never had chickenpox or been vaccinated usually receive two doses of the vaccine, four to eight weeks apart. If you don't remember whether you've had chickenpox or the vaccine, a blood test can determine your immunity.

The chickenpox vaccine isn't approved for:

• Pregnant women
• People who have weakened immune systems, such as those who are infected with HIV, or people who are taking immune-suppressing medications
• People who are allergic to gelatin or the antibiotic neomycin

Talk to your doctor if you're unsure about your need for the vaccine. If you're planning on becoming pregnant, consult with your doctor to make sure you're up to date on your vaccinations before conceiving a child.

Is it safe and effective?

Parents typically wonder whether vaccines are safe. Since the chickenpox vaccine became available, studies have consistently found it to be safe and effective. Side effects are generally mild and include redness, soreness, swelling and, rarely, small bumps at the site of the shot.

Diagnosis

Doctors generally diagnose chickenpox based on the rash.

If there's any doubt about the diagnosis, chickenpox can be confirmed with lab tests, including blood tests or a culture of lesion samples.

Treatment

In otherwise healthy children, chickenpox typically needs no medical treatment. Your doctor may prescribe an antihistamine to relieve itching. But for the most part, the disease is allowed to run its course.

If you're at high risk of complications

For people who are at high risk of complications from chickenpox, doctors sometimes prescribe medications to shorten the length of the infection and to help reduce the risk of complications.

If you or your child are at high risk of complications, your doctor may suggest an antiviral drug such as acyclovir (Zovirax, Sitavig). This medication might lessen the severity of chickenpox when given within 24 hours after the rash first appears. Other antiviral drugs, such as valacyclovir (Valtrex) and famciclovir, also may lessen the severity of the disease, but might not be approved or appropriate for everyone.

In some instances, your doctor may recommend getting the chickenpox vaccine within three to five days after you've been exposed to the virus. This can prevent the disease or lessen its severity.

Treating complications

If complications develop, your doctor will determine the appropriate treatment. He or she may prescribe antibiotics for skin infections and pneumonia. Brain inflammation (encephalitis) is usually treated with antiviral drugs. You may need to be hospitalized.

Lifestyle and home remedies

To help ease the symptoms of an uncomplicated case of chickenpox, follow these self-care measures.

Avoid scratching

Scratching can cause scarring, slow healing and increase the risk that the sores will become infected. If your child can't stop scratching:

• Put gloves on his or her hands, especially at night
• Trim his or her fingernails

Relieve the itch and other symptoms

The chickenpox rash can be very itchy, and broken vesicles sometimes sting. These discomforts, along with fever, headache and fatigue, can make anyone miserable. For relief, try:

• A cool bath with added baking soda, aluminum acetate (Domeboro, others), uncooked oatmeal or colloidal oatmeal — a finely ground oatmeal that is made for soaking.
• Calamine lotion dabbed on the spots.
• A soft, bland diet if chickenpox sores develop in the mouth.
• Antihistamines such as diphenhydramine (Benadryl, others) for itching. Check with your doctor to make sure your child can safely take antihistamines.
• Acetaminophen (Tylenol, others) for a mild fever.

If fever lasts longer than four days and is higher than 102, call your doctor. And don't give aspirin to children and teenagers who have chickenpox because it can lead to a serious condition called Reye's syndrome.

Talk with your doctor before giving any type of nonsteroidal anti-inflammatory drug (NSAID) — such as ibuprofen (Advil, Motrin IB, others) — to someone who has chickenpox. Some studies suggest this type of medication may lead to skin infections or tissue damage.

Preparing for an appointment

Call your family doctor if you or your child has signs and symptoms common to chickenpox. Here's some information to help you get ready for your appointment.

Information to gather in advance

• Pre-appointment restrictions. Ask if there are any restrictions you or your child should follow, such as staying isolated so as not to spread infection, in the time leading up to the appointment.
• Symptom history. Write down any symptoms you or your child has had, and for how long.
• Recent exposure to possible sources of infection. Try to remember if you or your child has been exposed to anyone who might have had chickenpox in the last few weeks.
• Key medical information. Include any other health problems and the names of any medications you or your child is taking.
• Questions to ask your doctor. Write down your questions so that you can make the most of your time with your doctor.

Questions to ask your doctor about chickenpox include:

• What is the most likely cause of these signs and symptoms?
• Are there any other possible causes?
• What treatment do you recommend?
• How soon before symptoms improve?
• Are there home remedies or self-care steps that could help relieve symptoms?
• Am I or is my child contagious? For how long?
• How do we reduce the risk of infecting others?

Don't hesitate to ask any other questions.

What to expect from your doctor

Your doctor may ask:

• What signs and symptoms have you noticed, and when did they first appear?
• Has anyone else you know had signs and symptoms common to chickenpox within the last few weeks?
• Have you had or has your child had a chickenpox vaccine? How many doses?
• Are you or is your child being treated or have you recently been treated for other medical conditions?
• What medications are you or your child currently taking, including prescription and over-the-counter drugs, vitamins and supplements?
• Is your child in school or child care?
• Are you pregnant or breastfeeding?

What you can do in the meantime

Rest as much as possible, and avoid contact with others. Chickenpox is highly contagious until skin lesions have fully crusted.