What is asthma?

More than 3 million Canadians have asthma, a chronic condition characterized by cough, shortness of breath, chest tightness, and wheezing. Maintaining a healthy lifestyle, avoiding triggers, and working closely with a healthcare professional are the best ways to keep asthma under control.

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Risk factors

While the exact cause of asthma is not known, it appears to result from several factors, including:

  • genetics
  • obesity
  • the tendency to have allergic reactions
  • high exposure to airborne irritants (pet dander, house dust, mould, chemicals, and outdoor air pollution)
  • exposure to tobacco smoke during pregnancy and childhood
  • frequent respiratory infections early in life
  • indoor and outdoor air quality
  • low birth weight
  • respiratory distress syndrome


Asthma symptoms include:

  • cough
  • shortness of breath
  • tightness in the chest
  • wheezing

While asthma symptoms can almost always be controlled, they can sometimes be fatal. Talk to your healthcare professional about the warning signs that you may need emergency treatment.


Asthma symptoms and attacks (meaning episodes of more severe shortness of breath) usually occur after exposure to "triggers." Common triggers include:

  • cold or chest infections
  • allergens like pet dander, house dust, mould, chemicals, and outdoor air pollution
  • exposure to tobacco smoke
  • exercise
  • cold air
  • pollen
  • exposure to irritant fumes or gases

When people with asthma are exposed to triggers, they can have an asthma attack. During an attack, the airways in their lungs become inflamed and swollen.  As a result, the airways start to tighten and it becomes difficult to breathe. During some asthma attacks, the airways can also produce mucus, making it even harder to breathe.

Work closely with your healthcare professional to find out what your specific triggers are and how to avoid them.


"Asthma-like" symptoms do not always mean that someone has asthma. If you have more than one symptom and think that you may have asthma, visit your healthcare professional. A diagnosis is usually confirmed by medical tests.


There is no cure for asthma, but with the right information, treatment, and support, most people with asthma can control their symptoms and lead active, healthy lives.

Here are a few ways to help manage your asthma:

  • Work with your healthcare professional to develop a personalized asthma management plan.
  • Avoid or control triggers.
  • Take the right medication in the right way at the right time.
  • Schedule ongoing monitoring and follow-up appointments with your healthcare professional to assess symptoms and response to medication.


There are two types of asthma medications:

  • "Controllers" are medications taken daily on a long-term basis to keep asthma under control, mainly through their anti-inflammatory effects. These medications are usually inhaled through a device called a "puffer" or inhaler, but can also be taken in pill form or through injection.

    Tip: Knowing how to use your puffer correctly is important. Talk to your healthcare professional for tips on proper use.

  • "Relievers" are medications used on an as-needed basis that act quickly to reduce asthma symptoms.

    Tip: Talk to a healthcare professional if you need "reliever" medication more often as time goes on. You may need to adjust your asthma management plan.

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