Asthma is a chronic (long-term) disease in which a person’s airways are inflamed, making it difficult to breathe.

The airways become more inflamed when “triggers” are inhaled, which can cause them to produce more mucous and may also cause the muscles around the airway to tighten. These two factors together make it harder to breathe as the airway becomes smaller.

How common is it?

Asthma affects around three million Canadians.

Who can get it?

Anyone can get asthma. It is not contagious and causes are still unknown. Research has found there can be genetic (inherited) and environmental factors linked to asthma, but they are not always a cause. Environmental factors can include exposure to second-hand smoke and other air pollutants for a prolonged length of time.

What are the signs and symptoms?

The signs and symptoms of asthma can vary from minor to severe for every person and between people. For example, some people with asthma may only experience symptoms in certain situations (e.g., when exercising), while some may have symptoms all the time.

Common signs and symptoms include:

  • Shortness of breath
  • Tightness in the chest or chest pains
  • Whistling, wheezing sound when exhaling (especially in children)
  • Coughing or wheezing attacks which get worse when you have a cold or the flu

Signs that your asthma is getting worse:

  • Your symptoms are more frequent and more severe
  • It has become harder to breathe
  • You need to use your quick-relief inhaler more often

Certain situations or environments may cause your symptoms to get worse such as:

Exercise-induced asthma – Being active, especially in cold, dry, or humid conditions, can make symptoms flare up.

Occupational asthma – Asthma can be triggered by irritants at your workplace (e.g., chemical fumes, gas, dust).

Allergy-induced asthma – Symptoms can get worse when you’re exposed to things you’re allergic to (e.g., pet dander, pollen).

How is it diagnosed?

Symptoms of asthma may come and go. Persistent coughing is a common sign of lung disease, but can easily be mistaken for a chest infection or basic cough with a cold virus. If the coughing reaches the point that it regularly causes vomiting (especially in children), talk to your family healthcare provider about testing for asthma.

Only a doctor can diagnose asthma. They will rule out other medical conditions, allergies, and family history. Let them know when your symptoms get worse (e.g., when being active, when around pets, certain times of year) and how quickly they improve. Tests such as spirometry will be done to measure your air flow.

How is it treated?

Two kinds of medication are often used – one to control daily symptoms, and one to treat sudden attacks. Both medications come in the form of inhalers, devices containing medication which you breathe in. There are a variety of different inhalers and medication types; your doctor will help you find the inhaler that works best for you. These are only available through a doctor’s prescription.

Daily treatment - Controllers

Controllers, or “preventers”, are used daily to help reduce inflammation in the airways. Over time, you will have fewer symptoms as you gain control over your asthma. It is important to take the controller medication as directed by your doctor and to follow the plan, even if you feel like your asthma is under control. If you stop, your airways may become inflamed again, causing symptoms to return.

Symptom treatment - Relievers

Relievers are used to treat symptoms immediately, such as during an asthma attack. While these medications help with on-the-spot treatment, they do not replace your controller medication. Consider these a short-term, emergency solution only. It is important to monitor how often you need to use your reliever medication because it could mean your controller medication is not working properly, or your asthma is getting worse.

What are common triggers?

A trigger is a thing or condition that causes your asthma symptoms. Triggers will vary from person to person and can be grouped into two different categories: inflammatory and symptom.

Inflammatory triggers are allergens. These triggers will only affect people who have an allergy to them. Examples include:

  • Dust mites
  • Pet dander
  • Pollens
  • Moulds

Symptom triggers are non-allergic and can affect anyone with asthma. Examples include:

  • Smoke
  • Exercise
  • Chemical fumes
  • Air pollutants
  • Cold, dry, or humid air

Knowing and avoiding your triggers is a good way to avoid asthma attacks and keep inflammation as low as possible. 


The Asthma Society of Canada. (2017.) Asthma. Retrieved from

The Lung Association. (2017). Asthma. Retrieved from

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