The Asthma Society of Canada
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About Asthma
What Is Asthma?
How to Tell if You Have Asthma
Who Gets Asthma?
Common Asthma Triggers
What to Expect if You Have Asthma
What to Do if Your Asthma Worsens
Taking Control
Resources & Support
About Asthma

What Is Asthma?

Have you, or someone you know, been diagnosed with asthma? If so, you probably have lots of questions.

You may wonder, for example, just what asthma is. The medical definition of asthma is simple, but the condition itself is quite complex.

Doctors define asthma as a "chronic inflammatory disease of the airway" that causes the following symptoms:

  • Shortness of breath
  • Tightness in the chest
  • Coughing
  • Wheezing

Asthma has no set pattern. Its symptoms:

  • Can be mild, moderate or severe
  • Can vary from person to person
  • Can flare up from time to time and then not appear for long periods
  • Can vary from one episode to the next

The cause of asthma is not known, and currently there is no cure. However, there are many things you can do so you can live symptom-free.

Breathing: Normal Airway Versus Asthma Airway
In someone with normal lung function, air is inhaled through the nose and mouth. It passes through the trachea (also called the windpipe) before moving into the bronchi (large airways), which are branching tubes leading away from the trachea. The bronchi branch into smaller and smaller tubes, ending in many small sacs called alveoli. It's in the alveoli that oxygen, which the body needs, is passed to the blood, while carbon dioxide, which the body doesn't, is removed from it.

Normal Lungs

People with asthma often have trouble breathing when they're in the presence of what are called "triggers." When someone with asthma has asthma symptoms, it means that the flow of air is obstructed as it passes in and out of the lungs. This happens because of one or both of the following:

  • The lining of the airways becomes inflamed (irritated, reddened and swollen), and may produce more mucous. The more inflammation the more sensitive the airway becomes, and the more symptoms.
  • The muscles that surround the airways become sensitive and start to twitch and tighten, causing the airways to narrow. This usually occurs if the inflammation is not treated.

Both of these factors cause the airways to narrow, making it difficult for air to pass in and out of them.

The airways of someone with asthma are inflamed, to some degree, all the time. The more inflamed the airway the more sensitive the airway becomes. This leads to an increase in breathing difficulty.

Asthmatic Lungs

Asthma Can Affect Anyone
Asthma is a chronic condition, meaning it needs to be monitored and controlled over a lifetime.

Anyone can get asthma, although it's usually first diagnosed in young people. Currently, about three million Canadians have asthma.

Living with Asthma
Most people with asthma can live full, active lives. The trick is learning how to keep the asthma symptom-free. If you have asthma, you can control it:

Do You Have Asthma?

When is a cough more than a cough? What's the relationship between asthma and allergies, asthma and being constantly stuffed up, and asthma and acid reflux? Learn the signs to watch for as well as when to talk to your doctor.

More > >

Asthma Basics Booklet Series

We developed the Asthma Basics Steps to help you learn about good asthma control. Use these booklets to learn more about asthma diagnosis, triggers and medications, as well to guide your discussions with you doctor, pharmacist and asthma educator.

More > >

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DISCLAIMER: Content on this website is for information purposes only andnot a substitute for a qualified medical professional.
For specific information treatment and management your asthma and/or potential side effects of medications and
treatment, please consult your physician.