Asthma Triggers

Triggers are the things to which your airways are very sensitive — things that cause irritation or allergic reactions. These same things may not even bother other people. Contact with triggers can cause reactions that may intensify enough to set off an asthma attack when symptoms flare up. These triggers can cause you to react when the carpet is vacuumed, when you are around pets, or even when you go from a warm room into cold air.


The Domino Effect of Asthma Triggers

One of the best ways to understand how triggers work is to think of a line of dominoes. Imagine that the dominoes are upright, in line, quiet, and still. This domino line is similar to airways with asthma. The same way that airways with asthma are more reactive, these dominoes are not steady and can be easily tipped with even the slightest bump. Triggers set off reactions. They are like the bump that starts the cascade of dominoes knocking each other over.

The type and amount of triggers that cause a reaction in the airways are different for everyone with asthma. Triggers start an all-or-nothing effect. One trigger exposure can irritate airways and activate symptoms. The next trigger exposure causes symptoms to get even worse, and so on. Just like when one domino falls, the next one is knocked over, and it continues down the line.


Quick-relief medicines help stop the domino effect and put the dominoes back up in line. In other words, they can stop the tightening that causes symptoms to flare up. To keep your domino line from being knocked over, you want to avoid triggers to prevent even the very first domino from falling. Follow your doctor's treatment plan and take your control medicines that help stabilize your airways.

Reducing the Effects of Asthma Triggers

  • Identify and avoid triggers. The best way to avoid problems with triggers is to identify irritants, allergens, and conditions that cause asthma symptoms and take steps to avoid or minimize exposure to them. After a flare-up of asthma symptoms or an asthma attack, think about possible triggers and make a plan to avoid or reduce contact with these triggers.
  • Take medicine as directed. Another important way to prevent asthma attacks is to use long-term control medicines, as recommended by your doctor, to make your airways less reactive.


Identifying Your Triggers

Knowing your triggers is important to controlling your asthma and avoiding asthma attacks. Triggers and symptoms have a cause-and-effect relationship. Asthma symptoms increase in response to specific triggers. When you find a pattern to your symptoms, you can begin to identify and learn more about your triggers.

Many people with asthma also have allergies. Allergy symptoms are caused by an immune system reaction to things that do not affect people without allergies. Examples of an allergic reaction are skin rash, itching, sneezing, runny nose, watery eyes, digestive problems, coughing, breathing difficulty, wheezing, and other symptoms similar to asthma.


Allergens are the things that trigger an allergic reaction. Common allergens that bother some people include pet dander, dust mites, cockroaches, indoor and outdoor mold, certain foods, and pollen.

Allergic reactions are common. In people with asthma, allergic reactions can sometimes progress into an asthma attack. When you have allergies that are not controlled, asthma symptoms usually occur immediately and taper off when you are away from the allergen. Even if you have been away from the allergen for several hours, symptoms sometimes reappear. This is called a "late-phase reaction." Controlling your allergies is important and can improve your asthma symptoms.

Both allergens and irritants can trigger asthma. Irritants are substances (such as smoke, pollution, and strong smells) that irritate the airways but do not involve the immune system response that an allergen causes. When the bronchial tubes are inflamed, they become especially sensitive to these irritants.

People come into contact with irritants or allergens in many places: home, school, daycare, public places, the workplace, and just about anywhere they go. Symptoms often start many hours after contact with irritating substances such as gas, dust, smoke, perfumes, chemicals, or other fumes. Air quality may be responsible for some of these triggers.

When you suspect that exposure to something is a trigger, consider the following:

  • Other people in the same environment report reactions, even if their reactions do not trigger asthma symptoms.
  • When you are away from the area, symptoms clear up.


Other Types Of Asthma Triggers

Many other things can trigger asthma: sinus infections, gastroesophageal reflux disease (GERD), sensitivity to aspirin and non-steroidal anti-inflammatory drugs (NSAIDs), foods with sulfites (a food additive), beta-blocker medication, weather changes, menstruation, exercise, strong emotions, and respiratory viral infections such as colds.

Written by Karen Serrano, MD


Emergency Medicine resident at the University of Wisconsin-Madison.

Reviewed by Lisa V. Suffian, MD

Instructor of Clinical Pediatrics in the Division of Allergy and Pulmonary Medicine at Saint Louis Children's Hospital, Washington University School of Medicine

Assistant Clinical Professor in the Department of Pediatrics at Cardinal Glennon Children's Hospital, Saint Louis University

Board certified in Allergy and Immunology

Last updated June 2008