Health Topics


Chickenpox is a highly contagious illness caused by the varicella zoster virus.


  • Is usually a mild illness in healthy children.
  • Can be more severe in babies, adolescents, adults and people with weak immune systems.

Complications of chickenpox include:

  • Pneumonia - a lung infection
  • Encephalitis - swelling of the brain
  • Bacterial infections of the skin from scratching the rash

Pregnant women who get chickenpox and are not immune are at serious risk for complications, including death.  If a pregnant woman gets chickenpox, the fetus may become infected and develop congenital varicella syndrome, which can cause a variety of serious complications.  Risk to newborn babies can be significant.

The virus spreads easily:

  • By touching the fluid from chickenpox blisters
  • Through the air when an infected person coughs or sneezes
  • By touching secretions from an infected person

If you have chickenpox, you can spread the virus to others one to two days before the rash appears until about five days after the rash appears and the rash forms scabs. You are most infectious one or two days before rash the rash appears.

It is possible to get chickenpox from someone who has herpes zoster, also known as shingles, if you do not have immunity to the virus.

Chickenpox symptoms develop 10 to 21 days after contact with another person who has chickenpox.

Signs and symptoms

Initial symptoms of chickenpox include:

  • Fever
  • Tiredness
  • Loss of appetite
  • Runny nose
  • Headache

A few days later, a red itchy skin rash appears. The rash develops into fluid-filled blisters that dry and become scabs. The rash usually appears first on the chest, back and face, before spreading to other parts of the body, including the scalp, mouth, nose, ears and genitals.

Talk to your doctor if you think you or your child has chickenpox. 

You can use acetaminophen, commonly known as Tylenol, to relieve fever.  Do not give aspirin-containing products to children; they are associated with Reye’s syndrome.

You should cut fingernails short to prevent skin infections caused by scratching blisters.  Use calamine lotion and/or oatmeal baths to relieve itching.

Here are recommendations to prevent the spread of chickenpox:

  • According to the Canadian Pediatric Society, if your child has a mild illness without a fever, they can return to school or daycare as soon as they are well enough to take part in all activities, regardless of a rash
  • Stay away from newborn babies, pregnant women and people with weakened immune systems

The chickenpox virus stays in the body and can come back later as shingles in about 10 to 20% of the population. 

Here are some tips to prevent chickenpox:

  • The best way to prevent or reduce the severity of chickenpox is to get your varicella vaccine.  We recommend two doses of this free vaccine. Check to see when you and your child should get this vaccine.
  • If your child is immunosuppressed, you should ask their school to tell you when chickenpox is in your child’s class or at their school.
  • Pregnant women, newborn babies, teenagers, adults and people with weakened immune systems who have not had chickenpox or the varicella vaccine should call the doctor immediately if exposed to chickenpox or think they have chickenpox.  Make an appointment to see the doctor at the end of the day to limit exposure to other people.
  • If you are thinking about getting pregnant, but have not had the varicella vaccine or do not know if you are immune to chickenpox, talk to your doctor about the chickenpox vaccine.
  • If you think you have been in contact with a person with chickenpox and are not immune, talk to your doctor right away. You may be able to get a vaccine that could stop you from developing chickenpox or decrease the severity of the disease.

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