Asthma is a chronic inflammatory disease that affects the lining of the airways, causing bronchospasm.

The airways become inflamed and swollen and produce extra mucus. Episodes of asthma (called asthma attacks) occur when the airways narrow, making it difficult to breathe.

Inflamed Bronchus in the Lungs

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During an asthma attack, symptoms may range from mild wheezing (whistling or hissing sound as you breathe) to severe obstruction of the airways, potentially causing a life-threatening inability to breathe. Cough-variant asthma manifests as persistent, chronic cough without shortness of breath. Although asthma can be very serious, there are many ways to prevent and control symptoms.

The underlying cause of asthma is two-fold: 1) inflammation in the lining of the lung, and 2) structural changes in the lung due to inflammation and narrowing of air passages. Factors in the environment (both indoors and outdoors), called triggers, can make asthma symptoms worse and cause asthma attacks in people who have asthma.

Known asthma triggers include:

  • Allergens:
    • Pollen
    • Mold
    • Animal dander (fine scales from skin, hair, or feathers)
    • Dust mites
    • Cockroaches
  • Viral infections of the respiratory tract
  • Irritants:
    • Strong odors or sprays
    • Chemicals (including preservatives containing sulfites and dyes which are in many foods)
    • Air pollutants (especially ozone, nitrogen dioxide, and sulfur dioxide)
    • Changing weather conditions
  • Tobacco smoke or wood smoke
  • Drugs (including aspirin and other over-the-counter painkillers in individuals with a special type of asthma)
  • Exercise (especially when exertion occurs in a cold environment)
  • Emotional stress

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