Examples of things you might be allergic to are dust, pollen, molds, and animal dander. Some people have coughing or wheezing only during or after physical activity. This is called exercise-induced asthma. Asthma may be mild, moderate, or severe. An asthma attack may last a few minutes or for days.
Attacks can happen anywhere and at any time.
Severe asthma attacks can be fatal. It is very important to get treatment for asthma so you can live a healthy, active life. About 12 million Americans have asthma, and the number of people who have asthma is increasing worldwide. If you have asthma, the airways in your lungs are always somewhat inflamed, even when you do not have any symptoms. When your airways are exposed to irritants or allergens, the airways become more swollen and begin to make excess mucus.