What Causes Asthma?

From pollen, to smoke, to the flu: a range of triggers can cause asthma symptoms.

On this page


Asthma can be hard to predict. It can develop in young children and stay with them their entire lives. But some people don’t develop asthma until they are adults.

In some people, asthma symptoms don’t appear until they are exposed to a trigger such as smoke or pollen. Their immune system views these triggers as foreign substances and releases chemicals to combat them. For people with asthma, those chemicals can cause an asthma attack – meaning their airways tighten up, they have difficulty breathing and they may experience coughing or wheezing.

But if you have asthma, don’t let the fear of an asthma attack hold you back! An allergist can identify your triggers, then create a plan to help you avoid and manage them.

If coughing and wheezing are keeping you on the sidelines…

It’s time for an allergist.

Common Triggers

Different allergens and irritants can act as triggers for different people, but common asthma triggers include:

  • Outdoor allergens, such as pollens from grass, trees and weeds
  • Indoor allergens, such as pet danderdust mites, cockroaches and mold
  • Irritants in the air, such as smoke, chemical fumes and strong odors
  • Exercise (although people with well-controlled asthma can exercise)
  • Weather conditions, such as cold air or extremely dry, wet or windy weather
  • Certain drugs
  • Stress

Colds, Flu and Other Illnesses

Viral respiratory infections, including the flu, are the leading cause of acute asthma attacks.

Some people with heartburn have asthma symptoms when stomach acid backs up into the esophagus.

Drugs and Food Additives

Beta blockers, which often are prescribed for high blood pressure, glaucoma, migraine headaches and angina, can cause bronchospasm, an airway tightening. Patients with asthma should consult their allergist about the use of these medications.

Food additives rarely trigger asthma. The most common food trigger for asthma is sulfite, a preservative used in such products as frozen potatoes and some beers and wines.