Asthma Triggers

Reviewed by: HU Medical Review Board | Last reviewed: June 2023

Asthma is an ongoing (chronic) lung condition that causes airway inflammation. This leads to narrow airways and breathing problems. It also makes the airways more sensitive to allergens and other things you are exposed to. Symptoms can get worse after exposure to these triggers.1

Each person with asthma can have different triggers. Finding what triggers your symptoms can help you control your asthma. Talk to your doctor about how to identify and control your triggers.1

What are common asthma triggers?

Asthma triggers are usually things you breathe in (inhale). Many asthma triggers are allergens. Allergens cause your immune system to react. Other triggers are irritants. Inhaling triggers leads to asthma symptoms. An asthma attack can occur if symptoms start suddenly and get worse.2

Common inhaled triggers include:3-7

For some people, triggers may include:2-7

How do I know what triggers my asthma?

A great way to identify asthma triggers is to think about when your symptoms happen. Writing details down in a symptom journal can help you track any patterns. It may then be easier to connect your symptoms to common triggers.1

For example, if symptoms mostly happen at home, something in that environment may be a trigger. Consider whether any common asthma triggers are present in your home. If symptoms mostly happen at work, you may have work-related triggers. If symptoms worsen in the spring or fall, outdoor allergies may be involved.8

Your doctor may suggest allergy tests. These tests can see if you react to an allergen. But being allergic to something does not always mean that the substance will trigger asthma symptoms. Combining allergy tests with your symptom history can help identify allergic triggers.1

How can I control or avoid asthma triggers?

Reducing exposure to triggers is an important part of asthma control. Once you identify your asthma triggers, you have several options:1

  • Avoid the trigger completely
  • If you cannot avoid the trigger, limit your exposure
  • If you know you will be exposed to a trigger, ask your doctor about taking extra medicine ahead of time
  • Get allergy shots (immunotherapy)

When possible, completely avoiding triggers is the best way to prevent symptoms. It may not be possible to avoid your trigger, depending on the trigger and your situation. But you can make changes to reduce exposure to triggers. Depending on your specific triggers, some good steps may be:1,2,8

  • Avoiding smoking in your home or car, until you can quit
  • Washing bedding and vacuuming every week
  • Maintaining low indoor humidity and keeping surfaces dry
  • Keeping pets outside of the bedroom and off furniture
  • Using air filters that have HEPA filters
  • Keeping your home well-ventilated when showering and cooking
  • Limiting outdoor time if pollution or pollen levels are high

When you can predict your exposure to a trigger, taking extra medicine can help prevent symptoms. For example, even if exercise triggers symptoms, you should not avoid physical activity. One option is to take a quick-relief drug before exercising. Talk to your doctor about whether this is an option.1,2

In some cases, allergy shots can reduce your reaction to allergic triggers. This treatment is only available for common allergens (pollens, pet dander, dust, and mold). Allergy shots are most useful when there is a clear link between the allergen and asthma symptoms.9

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