Asthma Home > Causes of Asthma

Scientists have not yet determined the exact cause or causes of asthma. Possible causes include allergies to dust mites, pet dander, pollen, mold, and cockroaches, to name a few. Often, a combination of factors may trigger symptoms of asthma. Certain types of exercise can also lead to an attack. What causes or triggers the onset of asthma symptoms varies from person to person.

An Introduction to Asthma Causes

It is not clear exactly what makes the airways of people with asthma inflamed in the first place. Inflamed airways may be due to a combination of things. People are more likely to develop asthma if other family members have the condition. New research suggests that being exposed to things such as tobacco smoke, infections, and some allergens may increase the risk for developing asthma.

Asthma Triggers

There are factors that can make asthma symptoms worse and lead to asthma attacks.
Some of the more common things that can worsen asthma symptoms are:
  • Exercise
  • Allergens
  • Irritants
  • Viral infections.


Some people only have asthma with exercise or a viral infection. The following sections give some examples of things that can worsen asthma symptoms.

Common allergens that may be asthma triggers include:
  • Animal dander (from the skin, hair, or feathers of animals)
  • Dust mites (contained in house dust)
  • Cockroaches
  • Pollen from trees and grass
  • Mold (indoor and outdoor).
Some irritants that may cause asthma symptoms include:
  • Cigarette smoke
  • Air pollution
  • Cold air or changes in weather
  • Strong odors from painting or cooking
  • Scented products
  • Strong emotional expression (including crying, laughing hard, or stress).
Other Triggers
Other items that have been known to cause or worsen asthma symptoms include:
  • Medications (such as aspirin and beta-blockers)
  • Sulfites in food (dried fruit) or beverages (wine)
  • A condition called gastroesophageal reflux disease (GERD) that causes heartburn and that can worsen asthma symptoms, especially at night
  • Irritants or allergens in the workplace (such as special chemicals or dusts)
  • Infections.
This is not a complete list of all the things that can trigger or worsen asthma symptoms. People can have trouble with one or more of these. If you have asthma, it is important to learn which factors are problems for you. Your doctor can help you identify which things affect your asthma and ways to avoid them.
Written by/reviewed by:
Last reviewed by: Arthur Schoenstadt, MD
Last updated/reviewed:
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