Asthma is a chronic inflammatory disease that affects the airways that carry air in and out of the lungs. Having asthma means the inside walls of the airways are inflamed, or swollen, which makes them narrower. In addition, the inflammation of the airways can cause secondary symptoms.
For example, the bronchi become overly reactive and more sensitive to all kinds of asthma triggers, such as allergens, cold and dry air, smoke, and viruses. When the bronchi react, the muscles around them tighten, narrowing the airways even more.
Inflammation may also cause the cells in the airways to produce more mucus than usual, which can further narrow the airways. The narrowing of the airways can cause additional symptoms of coughing, wheezing, chest tightness, and others. These symptoms are most common at night and in the early morning.
When asthma symptoms become worse than usual, it's called an asthma episode or attack. In a severe asthma attack, the airways narrow so much that they can no longer deliver enough oxygen to the body's vital organs. In some cases, asthma attacks can be fatal.
Unfortunately, asthma can't be cured. However, most people with asthma are able to successfully manage their condition so that they have fewer, less-frequent symptoms and can live normal, active lives.