What Is Chickenpox?

Chickenpox is a viral infection that causes fever and an itchy rash with spots all over the body.

It used to be a common childhood illness in the United States, especially in kids under age 12. It's much rarer now, thanks to the varicella vaccine.

What Are the Signs & Symptoms of Chickenpox?

Chickenpox often starts without the classic rash, with a fever, headache, sore throat, or stomachache. These symptoms may last for a few days, with the fever in the 101°–102°F (38.3°–38.8°C) range.

The red, itchy skin rash usually starts on the belly or back and face. Then it spreads to almost everywhere else on the body, including the scalp, mouth, arms, legs, and genitals.

The rash begins as many small red bumps that look like pimples or insect bites. They appear in waves over 2 to 4 days, then develop into thin-walled blisters filled with fluid. The blister walls break, leaving open sores, which finally crust over to become dry, brown scabs.

illustration

All three stages of the chickenpox rash (red bumps, blisters, and scabs) appear on the body at the same time. The rash may spread wider or be more severe in kids who have weak immune systems or skin disorders like eczema.

What Causes Chickenpox?

Chickenpox is caused by the varicella-zoster virus (VZV). This virus also can cause a painful skin rash called shingles (herpes zoster) later in life. After someone has had chickenpox, the virus stays dormant (resting) in the nervous system for the rest of their life. The virus can reactivate ("wake up") later as shingles.

Kids who are vaccinated against chickenpox are much less likely to develop shingles when they get older.

Is Chickenpox Contagious?

Chickenpox is very contagious. Most kids with a sibling who's infected also will get it (if they haven't already had the infection or the vaccine), showing symptoms about 2 weeks after the first child does.

Someone with chickenpox can spread the virus:

  • through droplets in the air by coughing or sneezing
  • in their mucus, saliva (spit), or fluid from the blisters

Chickenpox is contagious from about 2 days before the rash starts until all the blisters are crusted over.

Someone with shingles can spread chickenpox (but not shingles) to people who haven't had chickenpox or the vaccine.

Because chickenpox is so contagious, a child who has it should stay home and rest until the rash is gone and all blisters have dried. This usually takes about 1 week. If you're unsure about whether your child is ready to return to school, ask your doctor.

What Problems Can Happen?

Some people are more at risk for complications from chickenpox, including:

  • pregnant women
  • newborns born to mothers who had chickenpox
  • patients with leukemia
  • kids receiving medicines that suppress the immune system
  • anyone with immune system problems

If they are exposed to chickenpox, they might be given a medicine (zoster immune globulin) to make the illness less severe.

Can Chickenpox Be Prevented?

Yes. Most people who get the chickenpox vaccine will not get chickenpox. And if they do get chickenpox, their symptoms will be much milder. 

Doctors recommend that kids get the chickenpox vaccine as:

  1. a first shot when they're 12–15 months old
  2. a booster shot when they're 4–6 years old

People 6 years of age and older who have never had chickenpox and aren't vaccinated can and should get two doses of the vaccine.

Kids who have had chickenpox do not need the vaccine — they usually have lifelong protection against the illness.

How Is Chickenpox Diagnosed?

Doctors usually can diagnose chickenpox by looking at the telltale rash.

Call your doctor if you think your child has chickenpox. The doctor can guide you in watching for complications and in choosing medicine to ease itching.

If you take your child to the doctor, let the staff know ahead of time that your child might have chickenpox. It's important not to expose other kids in the office — for some of them, a chickenpox infection could cause serious complications.

How Is Chickenpox Treated?

A virus causes chickenpox, so antibiotics can't treat it. But antibiotics are needed if bacteria infect the sores. This can happen when kids scratch and pick at the blisters.

An antiviral medicine might be prescribed for people with chickenpox who are at risk for complications. The depends on the:

  • child's age and health
  • extent of the infection
  • timing of the treatment

Your doctor can tell you if the medicine is right for your child.

How Can I Help My Child Feel Better?

To help relieve the itchiness and discomfort of chickenpox:

  • Use cool wet compresses or give baths in lukewarm water every 3–4 hours for the first few days. Oatmeal bath products, available at supermarkets and drugstores, can help to relieve itching. (Baths do not spread the rash.)
  • Pat (don't rub) the body dry.
  • Put calamine lotion on itchy areas (but don't use it on the face, especially near the eyes).
  • Ask your doctor or pharmacist about pain-relieving creams to apply to sores in the genital area.
  • Ask the doctor about using over-the-counter medicine to take by mouth for itching.

To prevent scratching:

  • Put mittens or gloves on your child's hands to avoid scratching during sleep. 
  • Trim fingernails and keep them clean.

If your child has blisters in the mouth:

  • Give cold, soft, bland foods because chickenpox in the mouth can make it hard to drink or eat. Avoid anything acidic or salty, like orange juice or pretzels.
  • Give your child acetaminophen to help relieve pain.

Never give aspirin to kids with chickenpox. It can lead to a serious illness called Reye syndrome.

When Should I Call the Doctor?

Most chickenpox infections don't need special medical treatment. But sometimes, problems can happen. Call the doctor if your child:

  • has a fever that lasts for more than 4 days
  • has a severe cough or trouble breathing
  • has an area of rash that leaks pus (thick, yellowish fluid) or becomes red, warm, swollen, or sore
  • has a severe headache
  • is very drowsy or has trouble waking up
  • has trouble looking at bright lights
  • has trouble walking
  • seems confused
  • is vomiting
  • seems very ill
  • has a stiff neck
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Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2020 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.

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