Asthma

Asthma is a long-term condition of the airways, the tubes that carry air in and out of your lungs. In asthma those tubes can swell, tighten and fill with mucus, so moving air takes more effort. Symptoms come and go, and they often flare after contact with a trigger such as a cold virus, cold air, exercise, smoke or an allergen.

What asthma is, and what it is not

Asthma is often described as a childhood condition that people grow out of. It does often start in childhood, but it can begin at any age, including after 50. Adult-onset asthma is sometimes linked to workplace exposures, a chest infection, or allergies that develop later in life, and it is identified with the same breathing tests used in younger people.

Asthma is also not the same as COPD, although both narrow the airways and cause breathlessness. Asthma tends to vary from day to day and often improves a good deal after an inhaled bronchodilator, while the airflow limitation in COPD does not fully reverse. Some people have features of both. Because asthma varies, one normal breathing test does not always settle the question, which is why a clinician may repeat testing or add a challenge test.

Signs and symptoms

• Wheezing, a whistling sound when you breathe out
• Coughing, often worse at night or early in the morning
• Shortness of breath, or feeling that you cannot get a full breath
• Tightness or pressure in the chest
• Waking at night because of coughing or breathing trouble
• Getting more out of breath than usual during everyday activity
• Needing a reliever inhaler more often than usual

Symptoms differ from person to person and change over time. Many people have long stretches with very little trouble, then a flare set off by a virus, cold air, exercise, smoke or an allergen.

What raises the risk

Some things cannot be changed:

• A family history of asthma, eczema or hay fever
• Being born early or with a low birth weight
• Sex and age, with asthma more common in boys during childhood and in women during adulthood

Others can often be worked on, usually with support from a health care team:

• Tobacco smoke, including second-hand smoke and vaping aerosol
• Indoor allergens such as dust mites, mould, cockroaches and animal dander
• Outdoor air pollution, traffic exhaust and wildfire smoke
• Workplace exposures such as flour dust, isocyanates, wood dust and cleaning chemicals
• Carrying extra weight, which is linked with harder-to-control asthma

How asthma is diagnosed in Canada

Asthma is usually confirmed with spirometry, a breathing test that measures how much air you can blow out and how fast, before and after an inhaled bronchodilator medicine. If spirometry is normal but asthma is still suspected, a methacholine challenge test or an exercise challenge test may be used to see whether the airways narrow. A clinician may also look at peak flow readings kept over time, arrange allergy testing by skin prick or blood IgE, and in some centres use a FeNO breath test that measures airway inflammation.

Treatment and day-to-day management

Clinical research for Asthma is enrolling. See the current studies ↓

Asthma care in Canada aims to settle inflammation in the airways, keep symptoms from limiting your day, and lower the chance of a flare-up. Depending on how often you have symptoms and what sets them off, a health care team may discuss:

• Inhaled medicines taken by puffer, spacer or nebuliser, including short-acting relievers and longer-acting controller inhalers that contain corticosteroids
• Oral medicines, including corticosteroid tablets during a flare-up and leukotriene receptor antagonists
• Biologic injectable therapies, handled through specialist severe asthma clinics for a small group of people whose symptoms continue on inhaled treatment
• Asthma education and a written asthma action plan, from certified respiratory educators, pharmacists and family practices
• Trigger assessment, allergy testing and allergen immunotherapy through allergists and respirologists

Inhaler technique, timing and choice all matter, and what suits one person will not suit another. These are decisions for you and your own clinician, and this page is not a recommendation about any of them.

When to talk to a doctor

• Call 911 if you are struggling to breathe, cannot speak in full sentences, your lips or fingernails look blue or grey, or your reliever inhaler is not helping.
• Seek urgent medical care the same day if you need your reliever inhaler more often than every four hours, or if symptoms keep waking you at night.
• Book a review with your family doctor, nurse practitioner or pharmacist if you use a reliever inhaler more than twice a week, or if asthma is limiting your usual activities.

Why clinical research matters for asthma

A large share of people living with asthma in Canada still have symptoms despite treatment. Asthma Canada reported that only 45 percent of respondents to its 2024 national survey believed their asthma was well controlled. Researchers still do not fully understand why some people respond to standard inhalers while others do not, or how to pick out the different biological subtypes of asthma early. Studies running in Canada include new and existing biologic therapies for severe or eosinophilic asthma, single-inhaler anti-inflammatory reliever strategies, digital and connected inhaler tools that track how medicines are actually used, and research on air quality and wildfire smoke exposure.

Clinical studies are how those questions get answered. Taking part is voluntary, you give informed consent before anything begins, and you can stop at any time without affecting the care you get from your own doctor. Joining a study does not mean giving up your current treatment, and no one can say in advance whether a study will help you personally.

Learn more from Canadian sources

• Asthma Canada
• Canadian Lung Association: Lung Health Information Line
• Public Health Agency of Canada: asthma and COPD in Canada
• Public Health Agency of Canada: chronic conditions in childhood