Facts about Influenza (the Flu)

HealthLinkBC File Number: 
12b
Influenza (Flu) Series
Last Updated: 
September 2015

What is influenza?

Influenza, often called the flu, is an infection of the upper airway caused by an influenza virus.

Getting sick with influenza also puts you at risk of other infections. These include viral or bacterial pneumonia which affect the lungs. The risk of complications, which can be life-threatening, is greater for seniors 65 years and older, very young children, and people who have lung or heart diseases, certain chronic health conditions, or weakened immune systems.

Healthy pregnant women in the second half of their pregnancy are at greater risk of being hospitalized following infection with influenza virus.

In Canada, thousands of people are hospitalized and may die from influenza and its complications during years with widespread or epidemic influenza activity.

How can influenza be prevented?

You can reduce the risk of getting influenza or spreading it to others by:

  • washing your hands regularly;
  • promptly disposing of used tissues in the waste basket or garbage;
  • coughing and sneezing into your shirt sleeve rather than your hands;
  • staying home when you are ill; and
  • getting an influenza vaccine.

Getting an influenza vaccine can help prevent you from getting sick with influenza and from spreading it to others.

How does influenza spread?

Influenza spreads easily from person to person through coughing, sneezing, or having face-to-face contact.

The virus can also spread when a person touches tiny droplets from a cough or a sneeze on another person or object and then touches their own eyes, mouth or nose before washing their hands.

An infected person can spread the influenza virus even before feeling sick. An adult can spread the virus from about 1 day before to 5 days after symptoms start. Young children may be able to spread the virus for a longer period of time.

What are the symptoms?

Influenza symptoms can include fever, headache, muscle pain, runny nose, sore throat, extreme tiredness, and cough. Children may also experience nausea, vomiting, or diarrhea. Although infections from other viruses may have similar symptoms, those due to the influenza virus tend to be worse.

Symptoms can begin about 1 to 4 days, or an average of 2 days, after a person is first exposed to the influenza virus. Fever and other symptoms can usually last up to 7 to 10 days, but the cough and weakness may last 1 to 2 weeks longer.

What is the home treatment?

If you get sick with influenza, home treatment can help ease symptoms. Follow the self-care advice below:

  • Get plenty of rest.
  • Drink extra fluids to replace those lost from fever.
  • Avoid smoking and ask others not to smoke in the house.
  • Breathe moist air from a hot shower or from a sink filled with hot water to help clear a stuffy nose.
  • Anti-influenza drugs or antivirals are available by prescription, but these must be started within 48 hours of the start of your symptoms to work best. These will shorten symptoms by about 3 days if given within 12 hours and by about 1.5 days if given within 2 days of the start of symptoms.
  • Non-prescription cough and cold medications are available for relief of influenza symptoms but these are not recommended for children less than 6 years of age.
  • Acetaminophen or Tylenol® can be given for fever or soreness. ASA or Aspirin® should NOT be given to anyone under 20 years of age due to the risk of Reye Syndrome. For more information on Reye Syndrome, see HealthLinkBC File #84 Reye Syndrome.

When should I see a health care provider?

Consult your health care provider early if you develop flu-like symptoms and you have a condition that puts you at higher risk of complications.

You should also call your health care provider if your symptoms get worse, such as shortness of breath or difficulty breathing, chest pain, or signs of dehydration (such as dizziness when standing or low urine output).

Is it influenza or a cold?

The following table can help you determine whether you have influenza or a cold.

Symptoms Cold Influenza (the flu)
Fever Rare Usual, sudden onset 39º-40ºC (102.2-104ºF), lasts up to 7 to 10 days
Headache Rare Usual, can be severe
Aches and pains Sometimes mild Usual, often severe
Fatigue and weakness Sometimes mild Usual, may last 2-3 weeks or more
Extreme fatigue Unusual Usual, early onset, can be severe
Runny, stuffy nose Common Sometimes
Sneezing Common Sometimes
Sore throat Common Sometimes
Chest discomfort, coughing Sometimes mild to moderate Usual, can be severe
Complications Can lead to sinus congestion or earache Can lead to pneumonia, respiratory failure, and more complications in persons with chronic diseases
Prevention Frequent hand washing Yearly influenza vaccine and frequent hand washing
Treatment No specific treatment is available; symptom relief only Antiviral drugs by prescription, which can reduce symptoms

For More Information

For more information, see the following HealthLinkBC Files:

ImmunizeBC logo BCCDC logo

Is it an emergency?

If you or someone in your care has chest pains, difficulty breathing, or severe bleeding, it could be a life-threatening emergency. Call 9-1-1 or the local emergency number immediately.
If you are concerned about a possible poisoning or exposure to a toxic substance, call Poison Control now at 1-800-567-8911.

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