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Diseases A–Z

Influenza (regular seasonal flu)

This page talks about regular seasonal flu (influenza). It explains flu symptoms, treatment, and prevention. It also talks about the flu shot.

What is the flu?

The flu is an infection of the nose, throat and lungs caused by the influenza virus.

In most people, the flu is uncomfortable and tiring. It can keep people in bed for days or even a couple of weeks. Some people are more at risk for serious complications from the flu, including seniors, young children, and people with long-term lung diseases like asthma and chronic obstructive pulmonary disease (COPD). Flu can make asthma symptoms worse and cause COPD flare-ups.

Flu can be fatal. Each year regular seasonal flu causes 4000-8000 deaths in Canada.

What causes the flu?

The flu is caused by the influenza virus. There are different strains (kinds) of influenza virus. They usually cause the same symptoms.

Signs and symptoms of the flu
  • headache
  • chills
  • cough
  • fever
  • loss of appetite
  • muscle aches
  • fatigue
  • runny nose, sneezing, watery eyes
  • throat irritation

Flu symptoms usually come on quickly.

Warning signs of severe flu in children — get emergency help if kids show one or more of these signs:
  • fast breathing or trouble breathing
  • skin is bluish or gray
  • blue or grey lips
  • not drinking enough fluids, hasn't peed (passed urine) in many hours, or no tears when she cries
  • lots of vomiting (throwing up)
  • not waking up, not paying attention to anything
  • cranky, doesn't want to be held
  • seizures
  • child's flu symptoms improve but then come back; she has a fever and her cough is worse
Warning signs of severe flu in adults — get emergency help right away if you have one or more of these signs:
  • it's hard to breathe, you're short of breath
  • blue or grey lips
  • pain or pressure in your chest or stomach
  • suddenly dizzy
  • confused
  • dehydrated, not peeing (no urine)
  • lots of vomiting (throwing up)
  • seizures
  • your flu symptoms improve but then come back; your cough is worse and you have a fever
Is the flu contagious (can you catch it)?

Yes. The flu is easy to catch, and easy to spread to other people.

The most common way the flu spreads is through people's hands. People with the flu often have flu germs on their hands because they've touched their eyes, nose or mouth. When they touch things — shake your hand, touch a tap or a doorknob — they can pass along the flu germs. If you touch something with flu germs on it, then touch your eyes, nose or mouth, you could get infected with the flu. This is why it's very important to wash your hands properly and often.

Flu germs can also travel through the air. If a person with the flu talks, sneezes or coughs, they can spray respiratory droplets (tiny drops of mucus) into the air. If these drops land in your nose, mouth or eyes, you can get the flu.

Learn more about how flu germs spread and how to prevent the flu.

How is the flu diagnosed?

Doctors often diagnose flu by observing your symptoms. To make a precise diagnosis, doctors use lab tests. They rub a swab in your nose or throat and send it to a lab for testing.

The lab can tell if you have a flu virus. If you do have a flu virus, it can say which particular strain (kind of flu) you have.

Treatment for the flu

Most of the time, people can take care of the flu at home:

  • Stay home and rest. Get lots of sleep.
  • Stay away from other people and avoid spreading your germs. Wash your hands, clean common areas, and take these other steps to avoid spreading your germs.
  • Drink lots of fluids:
    • water
    • broth
    • for adults and teens: sport drinks (for example, Gatorade©)
    • for kids: electrolyte drinks (for example, Pedialyte©)
    • for babies: continue breastfeeding, and give electrolyte drinks (for example, Pedialyte©)
  • For your headache, muscles aches and fever, you can take over-the-counter medicines like acetaminophen (for example, Tylenol©) or ibuprofen (for example, Advil©). Children and teens should not take aspirin (ASA or acetylsalicylic acid). If you're not sure what to take, call a pharmacist.
  • If you have asthma, keeping follow the advice in your asthma action plan. If you have COPD, follow the advice in your COPD action plan (PDF). You may have to take extra medicine to control your symptoms.

    If you don't know how to treat your asthma or COPD, or if your symptoms are out of control, see the doctor.

    If it's hard to breathe or your rescue medicine isn't working, call 911 or your local emergency number.
  • Watch for warning signs of severe flu. If you have these warning signs, get emergency help right away.
  • Call your doctor if you are not improving after a few days.

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How can I prevent the flu?

1. Get the flu shot every year. The flu shot is your best defence against the flu. It's recommended for most people over six months old, and especially recommended for people in high-risk groups:

  • seniors
  • children
  • childcare workers
  • healthcare workers
  • people with weak immune systems
  • people with chronic (long-term) diseases like asthma and COPD

The flu shot is not recommended for certain people:

  • people who have a severe allergy to chicken eggs or who have had a severe reaction to a flu shot in the past
  • children less than six months old
  • people who have a moderate or severe illness with a fever; they should wait until their symptoms lessen before they get the flu shot

2. Wash your hands properly and often and take other steps to fight germs.

3. Stay healthy: get plenty of sleep, exercise, and eat well. This helps your immune system stay strong and fight germs.

What else do I need to know about seasonal flu?

Sometimes people call an upset stomach "the stomach flu". There is no such thing as stomach flu. Most strains of flu (influenza) virus do not affect the stomach. When people have "stomach flu", it's usually a bacteria or virus infecting their stomach.

Where can I get more information on seasonal flu?

To get a flu shot, ask your family doctor or local public health unit. In most provinces, the flu shot is free for high-risk groups including seniors, children, and people with lung diseases like asthma and COPD.

For more information on flu prevention and immunization, see the website of The Canadian Coalition for Immunization Awareness & Promotion.

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