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Influenza - Just the Facts - Arabic (PDF)

What is the flu?

Influenza (the flu) is a respiratory infection caused by the influenza virus. The flu season (when most people get sick with the flu) often begins in late fall.

Learn More About the Flu

What are the symptoms of the flu?

After the germ enters the body, it can take 1-4 days before you may feel sick. Symptoms may include:

Photo of boy in bed with a thermometer in his mouth
  • Fever
  • Cough
  • Headache
  • Muscle aches
  • Stuffy and/or runny nose
  • Sore throat
  • Feeling unwell
  • Tiredness
  • For some children, nausea and vomiting may be present.

For the common cold, the symptoms are normally milder than the flu. Here is a chart that tells you the differences between the cold and the flu.

Who is at risk for complications from the flu?

Anyone can get the flu. Some people are at a higher risk for complications (such as pneumonia and worsening of underlying health conditions). They are much more likely to be admitted into the hospital because of the flu. These include:

  • Young children
  • Pregnant women
  • Older adults (65 years or older), especially those who live in group settings
  • People who have other health conditions, such as asthma or heart conditions

How is it spread?

The flu mostly spreads by breathing in contaminated air from an infected person who is sneezing, coughing, or speaking. You can also get infected by touching your eyes, nose, or mouth with your hands after touching contaminated hands, surfaces, or objects. The germ can live up to 24 hours on surfaces.

How long is it contagious?

A person with the flu may be contagious the day before symptoms begins and up to 7 days after. Children and people with a weakened immune system may be contagious for even longer.

How is the flu treated?

For a healthy adult, your body's immune system should be able to fight off the flu virus on its own. Symptoms may last 5 to 7 days. Treatment may include supportive care, drinking lots of fluids and getting plenty of rest. For more serious cases or during outbreaks, your health care provider might prescribe you medications, such as antivirals (fights viruses). Antibiotics (fights bacteria) cannot be used to treat the flu as it is caused by a virus.

How is the flu prevented?

Photo of elderly woman getting flu shot

For almost everyone 6 months of age or older, the best way to protect yourself is to get the flu vaccine early. It can take up to 2 weeks for the vaccine to work. By getting it early in the flu season, you are protected when the season peaks. It is also important to get the vaccine every year as the virus changes and your immune response decreases within a year. The flu vaccines are normally offered starting in October. You can get the vaccine from your health care provider or the pharmacy (for people older than 5 years of age).

Ways to prevent the spread of any infection include:

  • Washing your hands often for at least 15 seconds with warm water and soap. Avoid touching your eyes, nose, or mouth before you wash your hands.
  • Practicing respiratory etiquette, such as coughing and/or sneezing into your elbow or tissue.
  • Staying at home if sick.
  • Not sharing any personal items, such as cups and water bottles.
  • Cleaning and disinfecting surfaces that are often touched by others (such as door knobs, phones).


  • American Academy of Pediatrics. (2015). Red book: 2015 report of the Committee on Infectious Diseases. Elk Grove Village, IL: American Academy of Pediatrics.
  • Heymann, D.L. (2015). Control of communicable diseases manual, 20th edition. Washington, DC: APHA Press.
  • National Advisory Committee on Immunization. (2017). Canadian immunization guide chapter on influenza and statement on seasonal influenza vaccine for 2017-2018. Retrieved from
  • Ontario. Ministry of Health and Long-Term Care. (2014). Infectious diseases protocol, Appendix A: Disease-specific chapters, Chapter: Influenza. Toronto, ON: Queen’s Printer for Ontario.

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