Asthma is a chronic disease that affects the airways. Airways are tubes that carry air in and out of the lungs. Asthma causes the inside walls of the airways to become sore and swollen, which makes them very sensitive and may cause a strong reaction to allergens or irritants. When airways react to allergens or irritants, they get narrower and cause the lungs to get less air. This can cause wheezing, coughing, chest tightness and trouble breathing, especially early in the morning or at night.

Asthma is treated with two kinds of medicines: quick-relief medications to stop asthma symptoms and long term control medications to prevent symptoms. Most cases of asthma can be managed with proper ongoing therapy on an outpatient basis. Hospital admission for asthma is not a measure of hospital quality, but rather one way to measure outpatient care of asthma. Proper outpatient treatment may reduce the likelihood of hospital admission for asthma.