Flu (influenza)

The flu is a respiratory infection that spreads very easily. It is caused by the influenza virus.

The flu circulates each year in Québec and around the world. In Québec, it circulates mainly from late fall to early spring.

The length of flu season can vary. It can start earlier or later and be shorter or longer depending on the year.

Flu symptoms and their severity can vary with age and health status. The main symptoms are as follows:

• sudden fever:
  • between 38 °C and 40 °C (between 100.4 °F and 104 °F) for children, 
  • between 39 °C and 40 °C (between 102 °F and 104 °F) for adults;
• sudden cough;
• sore throat;
• muscle or joint pain;
• extreme fatigue;
• headache.

Symptoms can also include nausea, vomiting, diarrhea and abdominal pain. These symptoms are more common in children.

In older adults, feeling weak and confused sometimes may be the only symptoms.

The flu can be mistaken for other respiratory infections such as COVID-19 or a cold. For further information, see the Differences between a cold and the flu page.

Generally, the flu can be treated at home. To treat a flu at home, follow the advice in the Treatment section.

In some cases, however, you must see a doctor. If you don’t know if you or your child needs to see a doctor, call Info-Santé 811, option 1. A nurse will assess your situation and may be able to give you specific advice. The nurse will also be able to tell you if you should consult a doctor quickly or wait.

You can also follow the instructions below to find out whether a call to Info-Santé 811, consultation with a doctor or an emergency consultation is necessary.

Most healthy people recover from the flu on their own within 5 to 8 days. You must get plenty of rest and eat according to your appetite. Avoid forcing your child to eat; it is normal for your child to feel less hungry. Your child can resume normal activities when they feel well enough.

Avoid baths, alcohol rubdowns and fans because they can cause chills and increase the sick person’s temperature. Wear light clothing and keep the temperature of the sick person’s room at around 20 °C.

Coughing and fatigue may last up to 3 weeks or even longer. They are only worrisome if they are accompanied by persistent fever, breathing difficulties, a change in skin colouring or, in the case of children, pauses in breathing and choking.

You can relieve flu symptoms by taking the following measures:

• Drink plenty of fluids often
• Use medications as directed
• Perform nasal irrigation on your child

If you have a fever, your body naturally loses a lot of fluid, especially through sweating. It is therefore important that you or your child drink plenty of fluids often.

• Drink fluids, such as water, milk, juice or broth.
• Avoid alcoholic beverages, soft drinks or caffeinated drinks, such as coffee, tea and energy drinks. These drinks make you urinate, increasing fluid loss.
• If your child has been vomiting or has had diarrhea, watch for signs of dehydration.

In the absence of complications or risk factors for complications, you do not need prescription medication to treat the flu. However, to relieve fever and pain, you can take over-the-counter medications like acetaminophen (such as Tylenol®) or ibuprofen (such as Advil®).

Avoid taking medications that contain identical ingredients at the same time. For instance, do not take Tylenol® and Tylenol® Sinus together because both of these medications contain acetaminophen.

In some cases, your doctor or pharmacist may prescribe an antiviral medication to reduce the duration and severity of your symptoms. This type of medication is more effective when taken at the onset of an infection. To learn more, see the page Flu (influenza) antiviral medications for people at risk for complications.

Children and teenagers

If your child is over 3 months of age and has a fever, you can give them acetaminophen (such as Tylenol®), making sure to follow the instructions that come with the product, based on your child’s weight. If your child vomits, buy acetaminophen suppositories that you insert into the rectum. It is not recommended that a suppository be given within 4 hours after an oral dose was given, even if the child vomited the medication.

Fevers usually go down 1.5 to 2 hours after taking acetaminophen, then they go up again. That is how the medication usually works. Nevertheless, you must wait a minimum of 4 hours between doses.

Check with your pharmacist if you want to give your child over-the-counter cough and cold medication. Your pharmacist can help you find the right medication based on your child’s age and condition.

If your child suffers from health problems, consult your pharmacist or Info-Santé 811 before giving them over-the-counter medications. Avoid giving acetylsalicylic acid, also known as Aspirin, to children and adolescents. This medication could cause a serious brain and liver disease known as “Reye's syndrome” in children and teenagers who have the flu.

The flu can lead to complications. The most common complications are:

• dehydration due to sweating caused by fever;
• pneumonia;
• bronchitis;
• bronchiolitis (in French only)  in babies under 1 year old;
• sinusitis;
• otitis (ear infection).

For more vulnerable people, some complications can lead to hospitalization and even death.

People who have a higher risk of developing complications are:

• babies under 6 months of age;
• children and adults who have chronic diseases;
• pregnant women who have chronic diseases throughout their pregnancy;
• healthy pregnant women in the 2nd and 3rd trimesters of their pregnancy;
• people age 75 and over.

If you or your child has a higher risk of developing complications and you have flu symptoms, call Info-Santé 811. A nurse will assess your health and make recommendations based on your situation.

The flu virus prefers cool, dry places. It can live up to 2 days on contaminated objects and up to 5 minutes on skin.

The flu virus is very contagious. It spreads quickly from person to person:

• by droplets expelled into the air from the mouth or nose of a person infected with the flu when they cough or sneeze;

• by direct contact with secretions from the nose or throat of a person infected by the flu, such as by kissing;

• when you bring your hand to your nose, mouth or eyes after shaking the hand of a person who is infected or touching contaminated objects.

A person infected with the flu virus may be contagious:

• 24 hours before showing symptoms;
• up to 8 days after the onset of symptoms and sometimes even a little longer. Young children and older adults may be contagious for up to 14 days after the onset of symptoms.

If you have the flu, avoid direct contact with people who have a higher risk of developing complications as much as possible. This way, you reduce the risk of transmitting the illness to them.

The best way to protect yourself from flu-related complications is to get vaccinated. For further information, see the Flu Vaccination Program page.

Protection and hygiene measures can also help prevent the spread of the flu.

At all times

• Wash your hands often.
• Clean your immediate environment, such as furniture, counters, door handles and switches.
• Follow the steps for limiting the spread of respiratory infectious diseases.

If you have the flu

Stay at home as soon as you develop flu symptoms. Unless advised otherwise by a doctor, home is the best place to recover. By staying at home, you limit contact with other people or with other infections that may cause complications. You also limit the spread of the virus.

Follow the steps for limiting the spread of respiratory infectious diseases.