There are two basic types of asthma: allergic (extrinsic) asthma and non-allergic (intrinsic) asthma. While the two types have similar symptoms, their triggers are different.

Allergic asthma

Allergic asthma is caused by an allergic reaction in the lungs. An allergic reaction involves the inappropriate activation of the immune system toward a substance that does not normally cause disease (called an allergen). This common form of asthma is often triggered by inhaling an airborne allergen, such as mold or pollen, which causes the immune system of the lung airways to react, making the tissue swollen and inflamed. In people with allergic asthma, allergens cause the release of several natural chemicals (such as histamine) in the cells of the lung airways. These constrict the air passageways which results in the wheezing, coughing, chest tightness, and shortness of breath that accompany an asthma attack. Some common allergic asthma triggers include both inhaled and ingested substances such as:

• tree and plant pollen
• animal dander
• dust mites
• mold spores
• foods, such as peanuts, milk, and shellfish

Non-allergic asthma

Non-allergic asthma causes symptoms very similar to allergic asthma, but the triggers are different. Instead of inhaled allergens causing an inappropriate activation of the immune system, in non-allergic asthma something in the environment triggers inflammation that does not involve the immune system. The airways become inflamed, swell, and release mucus, obstructing air flow and leading to similar symptoms of coughing, wheezing, chest tightness, and shortness of breath. Some common triggers for non-allergic asthma include:

• environmental irritants, such as smoke, smog, perfumes, gasoline, and household cleaners
• respiratory infections, such as colds, flu, and sinus infections
• changes in breathing including exercise or laughter
• weather, such as dry wind or cold air
• strong emotions like anger, fear, stress, and excitement
• certain medications like aspirin
• pregnancy