When airways narrow and become clogged (left), your lungs get less air than during normal breathing (right).
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Asthma is a chronic disease that affects your airways. Your airways are tubes that carry air in and out of your lungs. If you have asthma, the inside walls of your airways become sore and swollen. That makes them very sensitive, and they may react strongly to things that you are allergic to or find irritating. When your airways react, they get narrower and your lungs get less air. This can cause wheezing, coughing, chest tightness, and trouble breathing, especially early in the morning or at night.
When your asthma symptoms become worse than usual, it's called an asthma attack. In a severe asthma attack, the airways can close so much that your vital organs do not get enough oxygen. People can die from severe asthma attacks.
Asthma is treated with two kinds of medicines: quick-relief medicines to stop asthma symptoms and long-term control medicines to prevent symptoms. Since the1970s and 1980s, researchers have developed new drugs designed specifically to reduce inflammation in asthma. Scientists are now exploring ways to stop the inflammatory process or prevent it from starting in the first place.
A microscopic view of dust mites, which feed off dead skin cells in bedding and carpets; they are a major trigger for asthma.
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Who Gets Asthma?
People get asthma because of an interaction between the environment in which they live and the genes they inherit.
Allergies: Most people with asthma have allergies. Your response to allergens—proteins from common materials like house dust mites, cockroaches, and pollens—may cause the inflammation that leads to asthma symptoms. Researchers are studying methods for reducing allergen levels to prevent inflammation. For example, many inner-city children are allergic to cockroaches and experience severe asthma. Reducing cockroach allergens and tobacco smoke in inner-city homes may help.
Environment: Researchers now suspect that susceptibility to asthma develops very early in life. A pregnant woman's cigarette smoking, exposures to allergens, and diet may play a role. Children's exposures to allergens and respiratory infections during the first three years of life may make them more likely to develop asthma.
Genetics: Genes also play a role in the development of asthma. Researchers are studying families in different ethnic and geographic communities to identify which genes are related to asthma. Genetic studies have also revealed differences in the ways patients respond to medications. Understanding the genetics of asthma should provide clues to preventing the disease and help physicians select the most effective treatments for individual patients.