Asthma Home > What Causes Asthma?

Doctors and scientists don't know for certain what causes asthma. Some of the difficulty in determining what causes it stems from the fact that what triggers asthma in one person may have no effect on another person. Possible causes include pet dander, dust, cold weather, or even a cold or flu, to name a few.

What Causes Asthma?

The cause of asthma is not yet understood. Both genetic and environmental factors appear to play roles in asthma. New research suggests exposures early in life to things such as tobacco smoke, infections, and some allergens may be among the possible asthma causes.
There is no cure for asthma, but it can be controlled by learning to avoid asthma triggers and by taking medicine.

Asthma Triggers

Many people with asthma have allergic reactions to particles breathed in through the air, such as animal dander and pollen. These common substances are called allergens, meaning that they cause an allergic reaction. The tendency to react to allergens by having an asthma attack is probably genetic.
Some common triggers include:
  • Animal dander (from the skin, hair, or feathers of animals)
  • Waste products from dust mites
  • Pollen from trees and grass
  • Mold (indoor and outdoor)
  • Cigarette smoke
  • Air pollution
  • Infections, such as colds and the flu
  • Exercise
  • Strong feelings or stress
  • Changes in weather or cold air
  • Strong odors from painting or cooking
  • Scented products
  • Certain medicines and foods.
This is not a complete list of all the things that trigger asthma. People may have trouble with one or more of these triggers. Everyone is different.
Written by/reviewed by:
Last reviewed by: Arthur Schoenstadt, MD
Last updated/reviewed:
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