Asthma is a chronic lung disease that makes it harder to move air in and out of your lungs. It causes recurring periods of wheezing, chest tightness, shortness of breath, and coughing.
When you breathe, air passes through your nose and down your throat into your lungs. Inside your lungs are branching tubes called airways. The airways are tubes that carry air into and out of your lungs. With asthma, the airways are often swollen (inflamed). The muscles that wrap around your airways can also tighten, making it hard to breathe.
Inflammation causes mucus to form. Mucus is a sticky, thick liquid that can further narrow the airways, making it even harder to breathe. When that happens, it’s called an asthma flare-up, asthma episode or asthma “attack”.
An asthma episode can occur when a person with asthma is exposed to an asthma trigger. A trigger could be a cold, the weather, or things in the environment, such as dust, pollen, chemicals, smoke and pet dander.
Treating symptoms when you first notice them is important. This will help prevent the symptoms from worsening and causing a severe asthma attack. Severe asthma attacks may require emergency care, and they can be fatal.
Asthma affects people of all ages, but it most often starts during childhood. In the United States, more than 25 million people are known to have asthma. About 7 million of these people are children.