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Chickenpox

Chickenpox (varicella) is a common, preventable childhood infection caused by the varicella-zoster virus. It’s most common in young children and is usually mild, but can be very uncomfortable for your child. When adolescents and adults get it, they can be very sick.

Chickenpox is very dangerous for people with immune system problems like leukemia, or for people taking medications that weaken the immune system.

What are the symptoms?

  • Chickenpox begins with a fever, aches and pains.
  • Within 1 or 2 days your child will get a rash. The rash is usually itchy and can make your child uncomfortable. It appears on the scalp and face, spreading quickly down the body and onto the arms and legs. The spots start as flat pink spots that turn into small water blisters. New spots will form even after others turn into blisters. Some children only get a few blisters, but others can have as many as 500. Blisters dry up and form scabs in 4 or 5 days.
  • Most children lose their appetite and have a headache during the first few days.

How is it spread?

Chickenpox spreads very easily. Because it can spread from 2 days before the rash appears, it often spreads without anyone knowing. It can also spread until all of the blisters have scabbed. 

  • The virus enters the body by the nose or mouth. It usually develops 2 to 3 weeks after contact with an infected person.
  • ​It is mainly spread through the air. The virus can survive in the air for several hours. It can be caught by being in a room with an infected person or in a room where someone with chickenpox has been recently.
  • It also spreads from person to person through direct contact with the virus. You can get chickenpox if you touch a blister, or the liquid or wet crust from a blister.
  • A pregnant woman with chickenpox can pass it on to her baby before birth.
  • Mothers with chickenpox can also give it to their newborn babies after birth.

If one of your children has chickenpox, it will probably spread to other members of the household who have not already had chickenpox or the chickenpox vaccine.

Chickenpox cannot live on objects like sheets, counters or toys. 

Can chickenpox cause bigger problems?

  • Babies who get chickenpox from their mothers before birth could be born with birth defects like skin scars, eye problems, brain damage or arms and legs that are not fully formed.
  • Chickenpox can be very severe or even life-threatening to babies in the first month of life, to adolescents and adults, and to anyone who has a weak immune system.
  • Children with chickenpox can get pneumonia (infection of the lungs) or get inflammation of the brain.
  • The blisters can get infected with bacteria and this can lead to lifelong scars. Though most of these infections are minor and clear up on their own, some can lead to a serious illness called necrotizing fasciitis (or “flesh-eating disease”).

Can you have chickenpox twice?

In most cases, you can only get chickenpox once. This is called life-long immunity. But in rare cases, a person might get it again, especially if they were very young when they had it the first time.

What is shingles?

Shingles looks like chickenpox and is caused by the same virus. But it usually appears on only one part of the body, where it causes pain. Shingles can happen in people who have already had chickenpox but usually many years later since after we have chickenpox, the virus stays with us in an inactive form. Shingles is contagious, but only to those who have never had chickenpox.

How can I treat chickenpox?

  • If your child gets chickenpox, do not give aspirin [acetylsalicylic acid (ASA)] or any products that contain aspirin. Taking aspirin increases the risk of getting Reye's syndrome. This severe illness can damage the liver and brain. If you want to control your child's fever, use acetaminophen (Tylenol, Tempra, Panadol and others).
  • Encourage your child not to scratch. Scratching can cause infection from bacteria that get into the skin. Adding baking soda to bathwater can be soothing. Your doctor may recommend a cream to help reduce the itch.
  • Infants with chickenpox, and older children or adults with a severe disease may be treated with antiviral drugs.

When should I call the doctor?

  • A new fever develops after the first couple of days. That is, the fever goes away for a day or so and returns.
  • Your child looks ill (not wanting to play, eat or drink), especially if he also has a high fever or has many spots inside the mouth.
  • A chickenpox spot becomes enlarged, red or very sore. Your doctor will decide if your child has developed a bacterial infection that needs antibiotics.

Can my child with chickenpox go to child care or school?

Many schools and daycare centres have policies that require children with chickenpox to stay home for 5 days after the rash appears. The goal is to protect other children from the disease. Unfortunately, this does not stop chickenpox from spreading.

Chickenpox is contagious from 1 to 2 days before the rash appears, and most infectious from 12 to 24 hours before the rash appears. It spreads through the air, not just by direct contact with the rash. Policies that require that your child stay home for a period of time don't work because by the time it's known that a child has chickenpox, it has already been passed on to other children.

If your child is too sick to take part in regular activities or if he has a fever, he should stay home. For mild cases (low fever for a short period of time and only a little rash, less than 30 spots), children can go to child care or school if they feel well enough to take part in regular activities, and if the child care center or school permits.

What if I'm pregnant?

Pregnant women can develop severe chickenpox. Most adult women are already protected against chickenpox by antibodies in their blood. If you are thinking of getting pregnant and have not had chickenpox, you should be vaccinated. If you are pregnant and have not had chickenpox, call your doctor right away if you are exposed to chickenpox. Your doctor may want to give you a special type of injection (VariZIG) to help prevent you from getting a severe infection. 

If you catch chickenpox early in your pregnancy, there is a 2% chance of it harming your unborn baby. 

How can I protect my child?

The best way to protect your child from chickenpox is vaccination.

If your child is not yet vaccinated and comes in contact with another child or family member who has chickenpox, he may still be protected if he is vaccinated right away.

If your child has an immune system disorder and comes in contact with chickenpox, call your doctor right away. The doctor can give a special type of immune globulin (VariZIG) with a large number of antibodies to help prevent infection, or early treatment with an antiviral drug.



Reviewed by the following CPS committees:
Infectious Diseases and Immunization Committee

Last Updated: July 2015