Influenza, commonly known as the flu, is a respiratory illness caused by viruses that affect the nose, throat and lungs. Flu season, the peak time for influenza, is November through April each year. The flu vaccine is your best defence to protect yourself and your family against the flu.
How do you get the flu?
The flu is spread from person to person through coughing or sneezing, or by touching surfaces that are contaminated with the virus.
To protect yourself from the flu you can:
- Frequently wash your hands with soap and running water, or use an alcohol-based hand rub
- Frequently clean and disinfect common surfaces and items
- Get your flu vaccine
Symptoms
Symptoms usually start one to four days after being exposed to the virus. Most people will recover in seven to ten days. Individuals in high-risk groups could experience more severe complications.
You may have the flu if you have:
- Fever
- Chills
- Cough
- Runny nose
- Stuffy nose
- Sore throat
- Headache
- Muscle ache
- Extreme weakness and tiredness
Influenza is often confused with the common cold. Read Flu Facts to compare your symptoms.
If you think you have the flu, you should:
- Stay home until your symptoms begin to go away; get plenty of rest
- Cover your mouth and nose with your arm or a tissue when coughing or sneezing
- Do not visit people in hospital or long-term care facilities
- See your health care provider if:
- You do not start to feel better after a few days
- Your symptoms get worse
- You are in a high-risk group and develop flu symptoms
Complications
Flu-related complications can affect anyone but they are more common for those in a high risk group. This includes:
- Older adults (people 65+ years)
- Children under five years old
- Pregnant women
- People with underlying health conditions
Complications from the flu can include pneumonia, which is a serious illness. It is estimated that flu causes approximately 12,200 hospitalizations and 3,500 deaths in Canada each year.
Flu vaccine
The 2024-2025 flu season has ended. The annual flu vaccine program will start in late October, 2025. Flu season generally lasts from November to April each year.
The flu vaccine is the best way to reduce your risk of getting sick with influenza and spreading it to others. In elderly people, the vaccine can prevent pneumonia, hospitalization and death. Protection against the flu protects us and those most vulnerable in our families and community.
The vaccine is free and available to anyone six months of age and older in Ontario.
Check back in late October, 2025 for more information on how to get the flu vaccine.
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