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

Common Asthma Triggers

About Inflammatory Triggers | About Symptom Triggers

About Inflammatory Triggers

Dust Mites
Dust mites are tiny, spider-like creatures that eat the skin particles humans shed. These little creatures live wherever there is a lot of human contact and in humid environments. You can find dust mites in:

  • Bedding (pillows, sheets and blankets)
  • Carpets
  • Stuffed toys
  • Sofas and mattresses
  • Curtains

While dust mites are generally harmless, their body parts and droppings contain a substance that can cause inflammation of the airways in those who are allergic.

Many types of animals - both pets you have at home and animals you may encounter outside - have been shown to trigger airway inflammation in people who are allergic. These include:

  • Cats (which are the worst offenders)
  • Dogs
  • Gerbils, hamsters
  • Rabbits
  • Mice
  • Birds
  • Other furry animals

You may have heard that dander (particles of an animal's skin) can be a significant asthma trigger. But many other things produced by animals - saliva, oil secretions, urine and feces - can serve as triggers too.

Up to 50% of children with asthma have symptoms triggered by pets. If you have a pet allergy consider finding a new home for the pet. If you decide to keep the pet even though you are allergic, you will be increasing the severity of your asthma over time. There is no such thing as an allergy-free dog or cat. All furred animals shed dander. Reducing your exposure to pet allergens is the most effective way to help your asthma symptoms.

If you can't find a new home for the pet, you can try to control your exposure to it and other animals.

The feces of cockroaches have been shown to trigger asthma symptoms. If there are cockroaches in your home, call a professional exterminator.

Found in almost any damp, humid place, moulds are a type of fungus. When moulds reproduce, they release spores into the air that can trigger asthma episodes. People with asthma can come into contact with these spores both outside and inside. The air is never free of mould, but you can prevent growth by keeping your house clean and dry all year.

Outside, moulds can grow in:

  • Piles of leaves
  • Cut grass
  • Stagnant water
  • Garbage containers
  • Composters

Fortunately, there are things you can do to avoid exposure to outdoor moulds.

Inside, you can find moulds growing in:

  • Basements
  • Bathrooms
  • Humidifiers
  • Dehumidifiers
  • Old houses
  • Cottages

Again, there's plenty you can do to control your exposure to indoor moulds.

Pollens are common allergens - substances that cause allergic reactions - that can also trigger asthma attacks. Pollens are carried by the wind on hot and windy days. Pollens are produced by:

  • Trees in the spring
  • Grasses in the summer
  • Weeds (especially ragweed) in the fall

While you can't avoid it altogether, you can limit your exposure to pollen.

Viral Infections
Viruses can both cause asthma episodes and make people with asthma more sensitive to other asthma triggers.

Viral triggers include:

  • The rhinovirus (common cold)
  • Respiratory syncytial virus (RSV)
  • Certain flu viruses

Your healthcare team can tell you about ways to avoid viral infections, and what to do when you get sick.

People with asthma are encouraged to get the flu shot in the Fall.

Air Pollutants
Some people with asthma find that going outside on smoggy days can make their symptoms worse. If you're one of them, try to stay indoors as much as possible if the air-quality index is high.

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.