Asthma is a chronic lung disease that affects a person's airways, which are tubes that carry air into the lungs and outside of the body. When a person has asthma, the linings of the airways become inflamed, which makes them strongly react to substances that a person is allergic to. Allergens include pollen, pet dander, cigarette smoke, or strenuous physical activities.
The airways tend to get narrower with the lungs getting less air when a person is exposed to certain allergens. For this reason, symptoms, such as coughing, wheezing, difficulty breathing, and chest tightness develop, particularly at night and early in the morning. When these symptoms become worse, it is called as an asthma attack. People can also die from a severe asthma attack, so it is very important to control or manage the disease with long-term treatment or rescue medicines from a flare.