Chickenpox (varicella) is a viral infection that causes an itchy, blister-like rash. Chickenpox is highly contagious to people who haven't had the disease nor been vaccinated against it. Before routine chickenpox vaccination, virtually all people had been infected by the time they reached adulthood, sometimes with serious complications. Today, the number of cases and hospitalizations is down dramatically.

For most people, chickenpox is a mild disease. Still, it's better to get vaccinated. The chickenpox vaccine is a safe, effective way to prevent chickenpox and its possible complications.

Chickenpox infection usually lasts about five to 10 days. The rash is the telltale indication of chickenpox. 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
  • Fluid-filled blisters (vesicles), forming from the raised bumps over about one day before breaking and leaking
  • Crusts and scabs, which cover the broken blisters and take several more days to heal

New bumps continue to appear for several days. As a result, you may have all three stages of the rash — bumps, blisters and scabbed lesions — at the same time on the second day of the rash. Once infected, you can spread the virus for up to 48 hours before the rash appears, and you remain contagious until all spots crust over.

The disease is generally mild in healthy children. In severe cases, the rash can spread to cover the entire body, and lesions may form in the throat, eyes and mucous membranes of the urethra, anus and vagina. New spots continue to appear for several days.

When to see a doctor

If you suspect that you or your child has chickenpox, consult your doctor. He or she usually can diagnose chickenpox by examining the rash and by noting the presence of accompanying symptoms. Your doctor can also prescribe medications to lessen the severity of chickenpox and treat complications, if necessary. Be sure to call ahead for an appointment and mention you think you or your child has chickenpox, to avoid waiting and possibly infecting others in a waiting room.

Also, be sure to let your doctor know if any of these complications occur:

  • The rash spreads to one or both eyes.
  • The rash gets very red, warm or tender, indicating a possible 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 103 F (39.4 C).
  • Anyone in the household is immune deficient or younger than 6 months old.

Chickenpox, which is caused by the varicella-zoster virus, is highly contagious, and it can spread quickly. The virus is transmitted by direct contact with the rash or by droplets dispersed into the air by coughing or sneezing.

Your risk of catching chickenpox is higher if you:

  • Haven't had chickenpox
  • Haven't been vaccinated for chickenpox
  • Work in or attend a school or child care facility
  • Live with children

Most people who've been vaccinated against chickenpox or who've had chickenpox are immune to the virus.

Chickenpox is normally a mild disease. But it can be serious and can lead to complications, especially in high-risk people. Complications include:

  • Bacterial infections of the skin, soft tissues, bones, joints or bloodstream (sepsis)
  • Pneumonia
  • Inflammation of the brain (encephalitis)
  • Toxic shock syndrome
  • Reye's syndrome for people who take aspirin during chickenpox

Who's at risk?

Those at high risk of having complications from chickenpox include:

  • Newborns and infants whose mothers never had chickenpox or the vaccine
  • Adults
  • Pregnant women who haven't had chickenpox
  • People whose immune systems are impaired by medication, such as chemotherapy, or another disease, such as cancer or HIV
  • People who are taking steroid medications for another disease or condition, such as children with asthma
  • People taking drugs that suppress their immune systems

Chickenpox and pregnancy

Other complications of chickenpox affect pregnant women. Chickenpox early in pregnancy can result in a variety of problems in a newborn, including low birth weight and birth defects, such as limb abnormalities. A greater threat to a baby occurs when the mother develops chickenpox in the week before birth. Then it can cause a serious, life-threatening infection in a newborn.

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 another disease caused by the varicella-zoster virus called shingles. After a chickenpox infection, some of the varicella-zoster virus may remain in your nerve cells. Many years later, the virus can reactivate and resurface as shingles — a painful band of short-lived blisters. The virus is more likely to reappear in older adults and people with weakened immune systems.

Shingles can lead to its own complication — a condition in which the pain of shingles persists long after the blisters disappear. This complication, called postherpetic neuralgia, can be severe.

A shingles vaccine (Zostavax) is available and is recommended for adults age 60 and older who have had chickenpox.

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 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 or 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 breast-feeding?

What you can do in the meantime

While you wait for your appointment, you may be able to reduce fever with ibuprofen (Advil, Motrin IB, others) and acetaminophen (Tylenol, others). Anyone recovering from chickenpox shouldn't take aspirin. This is because aspirin has been linked to Reye's syndrome, a rare but potentially life-threatening condition, in people recovering from chickenpox.

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

Doctors generally diagnose chickenpox based on the telltale rash.

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

In otherwise healthy children, chickenpox typically requires 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 have a high risk of complications from chickenpox, doctors sometimes prescribe medications to shorten the duration of the infection and to help reduce the risk of complications.

If you or your child falls into a high-risk group, your doctor may suggest an antiviral drug such as acyclovir (Zovirax) or another drug called immune globulin intravenous (IGIV). These medications may lessen the severity of the disease when given within 24 hours after the rash first appears. Other antiviral drugs, such as valacyclovir (Valtrex) and famciclovir (Famvir), also may lessen the severity of the disease, but they have been approved for use only in adults. In some cases, your doctor may recommend getting the chickenpox vaccine after exposure to the virus. This can prevent the disease or lessen its severity.

Don't give anyone with chickenpox — child or adult — any medicine containing aspirin because this combination has been associated with a condition called Reye's syndrome.

Treating complications

If complications do develop, your doctor will determine the appropriate treatment. Treatment for skin infections and pneumonia may be with antibiotics. Treatment for encephalitis is usually with antiviral drugs. Hospitalization may be necessary.

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

Don't scratch

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, 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) or ibuprofen (Advil, Motrin IB, others) for a mild fever.

Don't give aspirin to anyone with chickenpox because it can lead to a serious condition called Reye's syndrome. And don't treat a high fever without consulting your doctor.

The chickenpox (varicella) vaccine is the best way to prevent chickenpox. Experts from the Centers for Disease Control and Prevention (CDC) estimate that the vaccine provides complete protection from the virus for nearly 90 percent of young children who receive it. When the vaccine doesn't provide complete protection, it significantly lessens the severity of the disease.

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 immunization schedule. The vaccine can be combined with the measles, mumps and rubella vaccine, but 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 but 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.

If you've had chickenpox, you don't need the chickenpox vaccine. A case of the chickenpox usually makes a person immune to the virus for life. It's possible to get chickenpox more than once, but this isn't common. However, if you're older than 60, talk to your doctor about the shingles vaccine.

The chickenpox vaccine isn't approved for:

  • Pregnant women
  • People with weakened immunity, such as those with HIV or people 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 safe and effective. Side effects are generally mild and include redness, soreness, swelling and, rarely, small bumps at the site of the shot.

Mar. 26, 2013