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Chickenpox cover a child's face

What is Chickenpox?

Chickenpox is a very contagious and common illness with rash and fever caused by the varicella-zoster virus. Chickenpox illness usually lasts about 5 to 10 days and is usually a mild infection, however, it can be life-threatening to some.

Severe chickenpox covering a torso

What are the signs and symptoms of Chickenpox?

  • Itchy rash (small, red spots and bumps blistering over 3-4 days, then forming scabs)
  • Fluid filled blisters  (will come out over several days)
  • Fever
  • Cold-like symptoms (runny nose and cough)
  • Tiredness
  • Loss of Appetite
  • Headache

Chickenpox beginning to blister

Rash may be in the mouth, ears, genital areas and scalp. The rash first appears on the head and face, spreads quickly down the body and onto the arms and legs. The rash is usually worse on the face, chest, stomach and back than on the arms and legs. The pox (rash) progresses quickly and goes through stages.

The stages are:

  • Red spot
  • Blister filled with clear fluid (Vesicle)
  • Blister filled with cloudy fluid (Pustule)
  • Crust or scab.

New pox appear in clusters for 3 to 4 days, therefore pox in all stages could be present at the same time. The rash is itchy and may cause great discomfort.

How is Chickenpox spread?

The Chickenpox virus spreads easily. Anyone not previously infected or vaccinated (with 2 doses) against Chickenpox can get the infection if exposed. Chickenpox is spread:

  • Through direct contact or “person-to-person”.
  • In the air when an infected person coughs, talks or sneezes.  
  • By touching or breathing in the virus particles in the air from the fluid-filled rash.

Chickenpox may also be transmitted after a person has contact with someone with shingles.

Scabs from the healing blisters are not infectious. It may take 14 to 21 days to break out with a Chickenpox rash from the time a person is first exposed to the virus.

Is there treatment for Chickenpox?

Your healthcare provider is the best person to diagnose and recommend specific treatments. These are general treatment recommendations to help relieve symptoms and prevent skin infections.

  • Rest.
  • Drink plenty of fluids to avoid dehydration.
  • Stay cool, calm and dry. Becoming hot and sweaty will make the itching worse.
  • Use good hygiene (stay clean).
  • Stay out of the sun.
  • Do not scratch the itchy rash or pick the scabs because the skin can get infected. Keep nails cut short. Wear mitts or socks on the hands when sleeping to help avoid scratching during the night.
  • Have oatmeal baths, pat the skin dry and apply a calamine lotion to itchy areas. This may reduce the itching. Talk to your pharmacist to help you find over-the-counter products to relieve the symptoms.
  • Use non-aspirin medications, such as acetaminophen to treat fever. Never use aspirin for the fever with chickenpox. Talk to your pharmacist or your health care provider about over-the-counter medication that can be used to reduce fever.

How long is Chickenpox contagious?

Chickenpox is contagious 1 to 2 days before the rash appears and until all the blisters have dried and scabbed over (usually about 5 days) after the start of the rash.

What are the possible complications of Chickenpox?


Complications may happen in some healthy children. Some complications in children are:

  • Skin infections.
  • Pneumonia (infection of the lungs).
  • Encephalitis (infection in the brain)

Pregnant Women:

Women of childbearing age should discuss immunizations before pregnancy to ensure they are up to date on their vaccinations. Chickenpox Infection to a woman in the first trimester and early second trimester of pregnancy is very serious. If you are pregnant and think you may have been exposed to chickenpox consult your health care provider immediately for further individual advice. Transmission during pregnancy to the fetus can also happen. If a woman gets chickenpox in pregnancy, it requires prompt treatment within 24-48 hours from when the rash started to prevent complications to baby and mother.

Immune Comprised:

People with a weakened immune system (for example, someone with cancer or a chronic condition) should talk to their health care provider if they’ve been exposed to chickenpox. Those with weakened immune systems are at risk for more serious complications. A health care provider can advise you on an individual basis.  

How do I prevent Chickenpox infection?

There is a very effective vaccine to help prevent Chickenpox (Varicella Vaccine) and is routinely provided by Health Care Providers through the Publicly Funded Immunization program in Ontario.

Children with documented evidence of vaccination with 2 doses of varicella-containing vaccine are considered immune.

Can someone who has the Chickenpox vaccine still get the Chickenpox illness?

Some people who have been vaccinated for Chickenpox may still get the illness. They would have milder symptoms with fewer blisters because of the vaccine.

When should I call my Health Care Provider?

For people with chickenpox at risk of serious complications, call a health care provider if the person

  • has a weakened immune system
  • is pregnant
  • develops any of the following symptoms:
    • fever that lasts longer than 4 days
    • fever that rises above 38.9C (102°F)
    • any areas of the rash or any part of the body becomes very red, warm, or tender, or begins leaking pus (thick, discoloured fluid) These symptoms may point to an infection.
  • seems very sick
  • has trouble waking up or seems confused
  • difficulty walking
  • stiff neck
  • frequent vomiting
  • trouble breathing
  • severe cough

Health Care Providers / Schools and Child Care Providers:

Chickenpox is a Reportable Infection to the Health Unit. Please fill in the Chickenpox Register and fax it to 226-783-2132 by the next working day. Laboratories are required to fax lab confirmed case information to the Health Unit by the next working day.  Fax to 226-783-2132.

Exclusions from School/Daycare:

Exclude infected children from group settings until the rash has crusted over. Daycares and schools should notify parents and staff of varicella (chickenpox) in a classroom. Refer them to this webpage and   their health care provider. Those pregnant or immunocomprised (as discussed above) are at a higher risk if they have been exposed, and should seek individual advice from their health care provider immediately.

If you have any questions or concerns please call 519-258-2146 ext. 1420 during business hours.

For further information about human diagnostic testing, contact Public Health Ontario Laboratories Customer Service (Consulting with Health Care Providers on laboratory testing) or call.

Toll Free: 1-877-604-4567 or see case definition for approved/validated diagnostic tests.

Ontario’s Public Health Infectious Disease Protocol / Management of Varicella (Chickenpox)

Varicella (Chickenpox) Provincial Case Definition


Control of Communicable Diseases Manual. Ed: David L. Heymann. Washington DC, USA: American Public Health Association, 20th (edn) 2015.

Managing Infectious Diseases in Child Care and Schools. Ed: Aronson, S. and Shope, T. Illinois, USA: American Academy of Pediatrics, 3rd (edn) 2013.

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