In this section: Asthma Triggers | Indoor Triggers | Outdoor Triggers | Occupational Asthma | Pets & Animals

What are asthma triggers?

Asthma triggers are things in your environment that cause worsening of asthma symptoms or asthma attacks. Triggers can be anywhere, and avoiding triggers that are under your control will help you be better prepared to deal with triggers that are more difficult to avoid like pollen, smog and viruses.

Triggers often bring on asthma attacks. It is important to avoid your triggers in order to keep airway inflammation to a minimum and reduce your asthma symptoms. Your personal triggers can be very different from those of another person with asthma. Knowing what your triggers are is an important part of managing your asthma.

Taking steps to ensure your asthma is properly managed is the key to living a symptom-free life. Speak with your healthcare provider about taking a controller medication, creating an Asthma Action Plan and proper inhaler technique. Since some asthma triggers are impossible to avoid, it’s important to always carry your reliever medication with you just in case of a trigger causing an asthma attack.

Different types of triggers

There are two types of asthma triggers:

Inflammatory (allergic) triggers set off an allergic reaction and can cause inflammation of the lung airways or tightening of the airway muscles. Inflammatory triggers include dust mites, animals, cockroaches, moulds, and pollens. Identification of allergic triggers is best confirmed by an allergist’s assessment.

Symptom (non-allergic) triggers generally do not cause swelling, but they can provoke “twitchy” airways, especially if they’re already inflamed. Symptom triggers include smoke, exercise, cold air, chemical fumes (and other strong-smelling substances like perfumes & scented laundry products), and intense emotions.

Common Allergic Asthma Triggers

  • Dust mites
  • Moulds
  • Pollen
  • Animals/Pet Allergens (i.e. dander)
  • Food Allergies/Additives (i.e. sulphites)
  • Cockroaches
  • Other Allergens

Common Non-Allergic Triggers

  • Air pollutants (i.e. Smoke/Smog)
  • Exercise
  • Viral infections
  • Cold air/weather changes
  • Chemical fumes, scented products (perfumes, detergents etc.)
  • Intense emotions

What you can do to avoid triggers

In addition to properly managing your asthma with medications, it’s important to know what your asthma triggers so that you can avoid them.

  • Speak with your doctor about having an allergy test done. Write down what you are allergic to and learn how to avoid or reduce your allergen exposure.
  • Use an Asthma Action Plan and an asthma diary or journal to keep track of your asthma symptoms and what triggered them. Review your findings with your healthcare provider to determine your asthma symptoms.

Once you have a clear idea of the things that make your asthma worse, take action and make plans to control your exposure to these triggers. Some triggers will be difficult to avoid (i.e. pollen, air pollution, weather changes), but many of them are avoidable. Start with your own home, and its indoor asthma triggers — many of us spend a lot of time at home and its environment is under your immediate control.

Here are some tips for controlling your home environment:

  • Make your home completely smoke free
  • Clean frequently – especially floors, furniture, and fabrics like bedding that can trap allergic triggers like dust mites and pet dander
  • If you are allergic to your pet – consider finding a new, loving home for your pet. We know for many people this may not be an option so click here for tips on managing asthma and living with pets
  • Monitor the humidity in your home – living in a damp home is likely to make asthma symptoms worse and increase exposure to triggers like mould
  • Avoid using chemicals or other scented products that may trigger your asthma such as candles, scented cleaners and laundry products
  • Consider replacing carpeted floors, which can trap dust mites and allergens with hardwood or other smooth flooring that are easier to clean. If you have carpets make sure to vacuum and clean them frequently — keeping your carpets properly maintained will reduce the amount of allergens and your exposure to them
  • Consider using asthma & allergy friendly™ certified products in your home and workplace

Here are some tips for avoiding triggers outside your home:

  • Plan ahead of time if a place you are visiting will put you in contact with any of your triggers (i.e. pets, cigarette smoke) and look for ways to reduce exposure
  • Take your controller medication as prescribed and keep your reliever medication handy at all times
  • Check the local weather and air quality before heading out — useful tools like the Air Quality Health Index make it easy to gauge your risk ahead of time
  • If cold weather is one of your triggers, plan activities for the warmest part of the day and wear a scarf or face covering to protect yourself from breathing in cold air
  • If humidity or hot weather is a trigger, plan activities for the cooler times of day like early in the morning

Indoor Triggers

Many people are surprised just how many asthma triggers are within their home. By educating yourself about indoor triggers, you’ll discover simple ways to reduce their levels.

Outdoor Triggers

When you’re outdoors, you have less control over the asthma triggers you encounter. Still, there are things you can do to help reduce you exposure to outdoor triggers. 


You can encounter asthma triggers in your workplace and certain industries may place you at a higher risk of occupational asthma. Understand your workplace triggers.

Pets & Animals

Many types of pets and animals can be asthma triggers. Learn about managing your asthma while living with pets.

Wildfire Season Advice

Wildfire Smoke

Wildfire smoke contains many harmful pollutants, including fine particulate matter that settles deep in the lungs, worsening asthma symptoms.

Breath Easy: Triggers

Download a copy of our Breathe Easy Booklet Series on asthma triggers. It provides useful information on managing your asthma, avoiding triggers and staying symptom-free . [Click here to download in French].