Flu (influenza)


Flu vaccination campaign

To find out all the details on the flu vaccination campaign and to book an appointment, see the page Flu vaccination.


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.

When should a child see a doctor

Call Info-Santé 811 for your child

Call Info-Santé 811, option 1 if your child has the following symptoms:

  • a child aged between 3 and 6 months who was vaccinated more than 48 hours ago:
    • a fever of 38 °C or 100.4 °F,
    • a rectal temperature of 36 °C or 96.8 °F or less
  • a child under 2 years of age
    • a fever (38.5 °C or 101.3 °F) that has persisted more than 48 hours
  • any child, regardless of age:
    • who drinks and urinates less than usual
    • who presents mild to moderate signs of dehydration
    • whose fever is increasing rapidly
    • whose fever returns after subsiding for more than 24 hours
    • who is having a harder time breathing than usual
    • who presents symptoms that worsen or do not improve after 7 days.

Go to the emergency department immediately

You must go to the emergency department with your child immediately in one of the following situations:

  • if your baby is under 3 months of age, has a fever (38 °C or 100.4 °F) and has not been vaccinated in the past 48 hours
  • if your child, regardless of age, has one of the following symptoms:
    • a rectal temperature of 36 °C or 96.8 °F or less,
    • a fever that has persisted more than 48 hours AND is not alleviated by fever medication,
    • pale complexion or abnormal skin colouring,
    • more rapid or difficult breathing despite frequent nasal irrigation with saline water,
    • retracting: when the skin pulls below and between the ribs with each of the child’s breaths. Another sign of difficulty breathing is flaring nostrils.
    • difficulty feeding,
    • moderate to severe signs of dehydration
    • no reaction to stimulation, amorphous state and less alert;
  • if your child has a chronic illness or a weakened or deficient immune system AND has a temperature over 38.5 °C or 101.3 °F;

If you require immediate help with getting to an emergency department, call 9-1-1.

Additional information

  • Fever can last from 48 to 72 hours. Keep your child at home until the fever subsides.
  • Your child might be more irritable than usual. Young children might cry more frequently.

When should an adult see a doctor

Calling Info-Santé 811 

Call Info-Santé 811 if you are in one of the following situations:

  • you are out of breath;
  • you don’t know if you should see a doctor.

Same day consultation

You must see a doctor on the same day if you have flu symptoms and also one of the following symptoms:

  • persistent or increasing pain when breathing;
  • a fever that is getting worse or has lasted for over 5 days.

If your symptoms get worse or do not improve after 7 days, you must see a doctor.

You can get a consultation at a resource near you, such as at a medical clinic or at a CLSC. For further information or to find one of these resources, see the Getting a medical consultation with a health professional page.

Immediate consultation in an emergency department

You must go to the emergency department immediately if you have flu symptoms and one of the following symptoms:

  • persistent or increasing difficulty breathing;
  • blue lips;
  • severe chest pain;
  • persistent or increasing severe headache;
  • drowsiness, difficulty staying awake, weakness;
  • confusion, disorientation;
  • seizures (the body stiffens and muscles contract in a jerky and involuntary manner);
  • no urination for 12 hours, intense thirst.

If you require immediate help with getting to an emergency department, call 9-1-1.


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

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.

Use medications as directed

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.

Perform nasal irrigation on your child

Children with the flu can experience nasal discharge and congestion. Perform nasal irrigation on your child to relieve these symptoms. For further information on nasal irrigation techniques, see:


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

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

People who have a higher risk of developing complications

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.

Protection and prevention

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

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.

Last update: December 15, 2023


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