Influenza (FLU)

What is the Flu?

Influenza, also called the flu, is a serious, highly contagious viral infection of the nose, throat and lungs. Illness from the flu can last two to seven days. It may last longer in people with chronic diseases or the elderly. Some people get very ill, develop complications and are admitted to hospital. Some people will die from getting the flu.

How is it spread?

Anyone can get the flu. It is spread in the air by an infected person coughing or sneezing or by touching surfaces or objects contaminated with the flu virus, such as doorknobs, toys or unwashed hands.

What are the symptoms?

The flu causes high fever, dry cough, chills, sore throat, headache, muscle aches, and generally you feel very tired. Children can also have earaches, nausea, vomiting and diarrhea. Although colds and other viruses may cause similar symptoms, influenza weakens a person much more than other viruses.

Is it a cold or influenza?

Cold Symptom Influenza
rare fever usual – high fever (102°F/39°C to 104°F/40°C), sudden onset, lasts 3-4 days
rare headache usual – can be severe
sometimes – mild general aches and pains usual – often severe
sometimes – mild fatigue and weakness usual – severe, may last 2-3 weeks or more
usual extreme fatigue usual – early onset, can be severe
common runny, stuffy nose common
common sneezing sometimes
common sore throat common
sometimes – mild to moderate chest discomfort, coughing usual – can be severe
can lead to sinus congestion or earache complications can lead to pneumonia and respiratory failure; can worsen a current chronic condition; can be life-threatening

Most people who get sick with the flu can be cared for at home. If you have the flu, stay at home to prevent spreading the illness to others. Plan ahead for child care arrangements in case your child becomes ill and will not be going to school or daycare.

To speak with a registered nurse

Visit Telehealth Ontario or call 1-866-797-0000
TTY: 1-866-797-0007
Hours of operation : 24 hours, 7 days a week


The following symptoms may indicate complications and the sick person may need immediate medical care:

  • Chest pain
  • Shortness of breath
  • Rapid or difficulty breathing, or wheezing
  • Bluish or grey skin colour
  • Bloody or coloured mucus/spit
  • Sudden dizziness or confusion
  • Severe or persistent vomiting
  • Seizures
  • High fever that does not go away or comes back after 4-5 days
  • Low blood pressure
  • Dehydration (people may be dizzy when they stand up, they are not urinating, ill infants may not have tears when they cry)
  • Additional symptoms to watch for in children include:
    • Any fever in a baby less than 3 months of age
    • Not drinking enough fluids or not eating
    • Not waking or interacting
    • Irritable or not wanting to play or be held

How can I protect myself?

The flu shot can protect you. Anyone six months of age and older who lives, works or attends school in Ontario can get the flu shot for free. It takes about two weeks after getting the flu shot to be protected. The vaccine is needed every year because the flu strains may change. Children less than nine years old need two flu shots the first year they get the vaccine. They need one flu shot each year after. Check where to get the flu shot in your community.

What are side effects from the vaccine?

If you get the flu shot you can still get the flu, but you likely won’t be as ill. The flu shot may cause minor side effects such as redness, warmth, swelling where the needle was given, tiredness or a slight fever for a day or two. More severe reactions are rare. If you have trouble breathing, swelling of the mouth or face, hives, rash or seizure/convulsion, seek medical care immediately. Report any severe reactions to the health unit or your healthcare provider.

Who should not get this vaccine?

Do not get the vaccine if you(r):

  • had a serious allergic reaction to a past flu shot
  • child is under six months of age
  • have a high fever or serious infection worse than a cold on clinic day
  • had Oculo-respiratory Syndrome (ORS) after a past flu shot and needed to be admitted to hospital
  • had Guillain-Barre Syndrome (GBS) develop within eight weeks of a past flu shot

Speak to your healthcare provider or public health nurse if you are allergic to thimerosal (form of mercury), neomycin or kanamycin.

 What else can I do to protect myself and others?

  • Wash your hands frequently.
  • Cough or sneeze into your sleeve.
  • If you have influenza symptoms or feel unwell, stay at home and do not visit relatives or friends in hospitals or long-term care facilities.

If you have a question please call us at 519.482.3416 or toll-free at 1.877.837.6143. Ask to speak to a public health nurse on the Infectious Disease team.