Chickenpox (Varicella)

Cause

The varicella-zoster virus, one of the herpes viruses, causes chickenpox infection. The same virus that causes chickenpox also causes shingles (herpes zoster).

How it is spread

The chickenpox virus can spread easily from one person to another. It most often spreads through the respiratory tract, such as mucous membranes of the mouth and nose. You also can get chickenpox through the air from an infected person's sneezing or coughing. Less often, chickenpox is spread when fluid from a chickenpox blister gets on your skin.

In rare cases, a person can get chickenpox from the fluid of shingles blisters.

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.

What Happens

The first weeks after catching the virus

About 14 to 16 days after contact with a person infected with the virus, the first symptoms of chickenpox usually develop. Most people feel sick and have a fever, a decreased appetite, a headache, a cough, and a sore throat.

• Some children get 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 weak immune systems may get the first symptoms of chickenpox sooner than the usual 10 to 14 days after exposure.

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

The chickenpox rash

The chickenpox rash usually appears on the upper body about 1 or 2 days after the first symptoms start. The trunk usually is most affected, and 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:

• 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.

Possible complications

Skin infection is the most common complication for children under age 5. Skin infection can form after the rash is scratched. Scratching allows bacteria from the skin or under the fingernails to get into a chickenpox blister. The infection can become serious if it isn't treated. An infected blister also may leave a scar.

Some people also are at increased risk of more serious problems from chickenpox. This higher-risk group includes newborns, teenagers, adults—especially pregnant women—and those who have weak immune systems.

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 1 in 5 people who have chickenpox will later get shingles.^{footnote 1} The shingles vaccine can help prevent shingles or make shingles less painful.

What Increases Your Risk

You are at risk for chickenpox if you have not had chickenpox or the vaccine and you:

• Live with someone who has chickenpox.
• Are indoors for more than 1 hour with someone who has chickenpox.
• Are in the hospital and share a room with someone who later gets chickenpox or are cared for by a staff member who later gets chickenpox.
• Have a weak immune system.

After you have had chickenpox or the vaccine, you become immune to the virus. It is possible that you may have a slight reaction after reexposure, such as a few spots and a slight fever. But you aren't likely to get chickenpox more than once.

When To Call

Call your doctor now if you or your child with chickenpox has:

• A severe headache or constant vomiting, sensitivity to bright light, or unusual sleepiness or confusion. These may be signs of inflammation of the brain (encephalitis).
• Problems breathing or persistent coughing. These may be signs of varicella pneumonia.
• Red, warm, and sore skin, or if the chickenpox rash changes to bigger open sores. These may be signs of serious skin infection.

Call for an appointment with your doctor if:

• You are older than age 12, you aren't sure if you have ever had chickenpox or the vaccine, and you have been exposed to chickenpox.
• You or your child has a weak immune system and has been exposed to chickenpox.
• You are pregnant and have been exposed to chickenpox.
• You or your child has chickenpox and any of the following:
  • A fever that lasts longer than 24 hours
  • Severe itching that cannot be relieved by home treatment
  • Chickenpox rash on the eyeball
  • A rash that lasts longer than 2 weeks

If you are a teen or adult, are pregnant, or have a weak immune system, it's important to see your doctor as soon as you think you've been exposed to the chickenpox virus. Your doctor may want to give you a medicine that helps protect you from the virus.

Watchful waiting

A healthy child with chickenpox symptoms may not need to visit a doctor. You may be able to describe your child's symptoms to the doctor over the phone. Then your child won't have to leave the house and risk spreading the virus to others. But it's important to check with your doctor to find out if your child needs to be seen.

If you go to a doctor's office, ask if you need to take any precautions when you arrive to avoid spreading the infection. For example, office staff may take you directly to an exam room when you arrive, rather than have you wait in the lobby.

Exams and Tests

Chickenpox usually can be diagnosed based on how the chickenpox rash looks. For a healthy child, describing the rash over the phone to a doctor (rather than visiting the office) may be all you need to do.

Anyone who is over age 12, or pregnant, or has a weak immune system needs to be checked by a doctor as soon as you suspect chickenpox. When given right away, treatment can help prevent serious complications. For more information, see When to Call a Doctor.

At the doctor's office, your doctor will ask you about your symptoms and will examine you. This usually gives your doctor enough information to find out if you have chickenpox.

Chickenpox during pregnancy

A woman who has had chickenpox early in her pregnancy may want to have her fetus checked for birth defects. This can be done with a fetal ultrasound during the second trimester.

Find out if you are immune

If you have never had chickenpox or the chickenpox vaccine, you have no immunity against the virus. This means that the virus can make you sick—you can get chickenpox.

If you need to make sure you're immune to the chickenpox virus, a viral test can tell you. It makes sense to get a viral test if you aren't sure you're immune and you:

• Plan to or can possibly become pregnant. Having chickenpox immunity prevents complications of chickenpox during pregnancy.
• Are more likely than normal to get severely ill from chickenpox or to have complications of chickenpox.
• Are required to prove chickenpox immunity for work or school.

Treatment Overview

Treatment for chickenpox depends on your age, your health, how long it's been since you were exposed to the virus, and your symptoms.

• A healthy child with chickenpox may need only home treatment to help relieve itching and monitor fever. For more information, see Home Treatment.
  • Chickenpox: Controlling the Itch
• Healthy teens and adults with chickenpox usually have more severe symptoms than children and are at higher risk for complications than healthy children. If you are older than age 12, are pregnant, or have a weak immune system, your doctor may want to give you a medicine or vaccine that helps protect you from the virus. For more information, see Medications. Home treatment measures can also help to make you more comfortable.

Prevention

The chickenpox, or varicella, virus spreads easily from person to person. If you have never had chickenpox or the chickenpox vaccine, you have no immunity against the virus. This means that the virus can make you sick.

If you or your child is not immune, you can prevent chickenpox by getting the vaccine. It is recommended for:

• All healthy children 12 months of age and older who have not had chickenpox.
• Healthy people who aren't sure if they've had the vaccine or chickenpox as a child.
• Women who are planning to get pregnant but aren't pregnant yet.

For women who aren't immune, chickenpox and pregnancy can be a dangerous combination. Getting the vaccine when not pregnant prevents complications of chickenpox during pregnancy. Talk to your doctor about the right timing for the vaccine.

You can help prevent chickenpox by avoiding close contact with people infected with the virus. This is even more important if you have a weak immune system. But the virus can spread from an infected person even before symptoms develop.

Prevent chickenpox after being exposed to the virus

If you have been in contact with a person who has chickenpox and aren't sure if you are immune, a shot of the vaccine may prevent you from having the illness. Or it may make the illness milder.

If you can't have the chickenpox vaccine (for example, during pregnancy) a shot of antibodies (immunoglobulin) or an antiviral medicine may help delay or prevent the chickenpox.

For more information, see Medications.

Don't expose children to chickenpox

Before the chickenpox vaccine was available, families often had the virus for weeks at a time as it sickened one person, then the next. To "get it over with," some parents intentionally exposed their children to a child with chickenpox.

Now that the vaccine can protect against the virus, parents have a safer option than exposing their children to chickenpox. Do not expose a child to the chickenpox virus. Even young children can have serious (though rare) complications from the infection, including pneumonia or encephalitis.

Self-Care

Most healthy children, teens, and adults with chickenpox need only home treatment. But all teens and adults with chickenpox need to see a doctor. When given right away, treatment can help prevent serious complications.

If you have chickenpox, you don't need to stay in bed. But it's best to stay quiet and rest. Over-the-counter medicines can help relieve symptoms such as fever and itching.

Before you give medicine to your sick child, check with your child's doctor. Because of their small size, children are more sensitive than adults to the effects of some medicines. Use a measuring spoon or medicine cup to give liquid medicine to a child. Don't guess the amount or use a regular table spoon.

Reduce itching

The chickenpox rash itches. Do what you can to control the itch and avoid scratching. Scratching the blisters may cause a skin infection, or scars may form after the blisters heal.

You can take steps to control itching, such as taking oatmeal baths, applying cool compresses, and taking antihistamines. Check with your child's doctor before giving your child antihistamines.

• Chickenpox: Controlling the Itch

Monitor fever

Fever is your body's normal response to infection. A higher-than-normal temperature kills bacteria and viruses that cause illness. Fever medicines stop this natural process, so use one only when fever is causing discomfort.

You can help relieve a fever with over-the-counter medicine. Follow the package instructions carefully. If you give medicine to your baby, follow your doctor's advice about what amount to give. (Do not give aspirin to people younger than 20, because of the risk of Reye syndrome, a rare but serious problem).

Call your doctor if you or your child has a fever that lasts longer than 24 hours.

Prevent the spread of infection

If you or your child has chickenpox, don't return to work, school, or day care until after all blisters have crusted over, usually about 10 days after the first symptoms start. To help prevent spreading chickenpox, stay away from people who aren't immune.

Medicines

Medicines for chickenpox can:

• Prevent chickenpox by making you immune to it.
• Help make chickenpox less severe after you are exposed or have symptoms.
• Help relieve chickenpox itch, pain, and fever.

If you (or your child) are not immune to chickenpox and have been exposed to the virus, call your doctor. The right medicine depends on your health, age, how long it's been since you were exposed to the virus, and your symptoms.

Vaccination to prevent chickenpox

To prevent chickenpox, most people can get the chickenpox vaccine. To fully protect you, two doses are needed before you're exposed to the virus.

Some people can't get the chickenpox vaccine. They include women who are pregnant and people who have ever had an anaphylactic reaction to gelatin, neomycin, or any other substance in the vaccine.

Medicines to help reduce the severity of chickenpox

• Chickenpox vaccine. If you are exposed to chickenpox and you get the vaccine within 3 days, you may not get sick, or your illness may be mild. If you can't get the shot within 3 days, getting it up to 5 days after exposure may still help.^{footnote 2}
• Immunoglobulins. Immunoglobulins (IG) help the body's immune system recognize and destroy harmful bacteria and viruses in the body, such as the varicella virus. Pregnant women, newborns who are at high risk for getting chickenpox, and people who have certain immune system problems can get a shot of chickenpox IG soon after they are exposed to the virus. It can help prevent infection and help them feel better sooner.
• Antiviral medicine. Antiviral medicine, such as acyclovir, is usually used to treat adults who have weak immune systems. It's used after you start to have symptoms of chickenpox. Healthy children and adults usually don't need this medicine when they have chickenpox.

Medicines to relieve pain and discomfort

After you have symptoms of chickenpox, you can take over-the-counter medicines to help relieve discomfort. Check with your child's doctor before giving medicine to your child.

• Acetaminophen (such as Tylenol) or ibuprofen (such as Advil) to reduce pain and fever. Follow the package instructions carefully. If you give medicine to your baby, follow your doctor's advice about what amount to give. People over age 20 also can take aspirin to reduce fever. Do not give aspirin to anyone younger than 20, because of the risk of Reye syndrome.
• Oral antihistamines (such as diphenhydramine) to relieve itching. Talk to your doctor before using any antihistamine lotions or creams on yourself or your child. And check with your child's doctor before giving antihistamine pills to your child.
• Your doctor may prescribe antibiotics to you or your child if you get a skin infection from chickenpox blisters.