Asthma is a chronic disease that makes breathing difficult.  If you have asthma, your airways – the tubes through which air flows to and from your lungs – are very sensitive to things you are allergic to (allergens) or find irritating (irritants).  The airways react strongly to these things; the reaction causes the airways to narrow, so less air can move through them.

There are three kinds of reactions that cause this narrowing of the airways:

• Inflammation, which means the airways become red and swollen (inflamed)
• "Bronchoconstriction," which means the muscles surrounding the airways contract and tighten, squeezing the airways
• Over production of mucous, which means the cells in the walls of the airways produce more mucous than normal, clogging the airways

The narrowing leads to the symptoms of asthma, which include:

• Wheezing (a raspy, squeaking, or whistling sound when you breathe)
• Coughing
• A feeling of tightness in the chest
• Shortness of breath

There are two kinds of asthma, allergic and non-allergic. In allergic asthma, allergens cause the airways to become inflamed. The inflammation can lead the body to release histamines, chemicals that cause the swelling, mucous secretion, and muscle contractions.  (For more information about allergies and allergens, go to Key Point 2). 

In non-allergic asthma, irritants cause inflammation or bronchoconstriction.  Irritants can include, among others, smoke, viruses, hyperventilation, exercise, cold air, dry air, and even strong emotions such as anxiety and stress.

Allergens and irritants are usually called asthma "triggers" because they provoke asthma symptoms.  (However, some medical professionals distinguish between "triggers" which cause bronchoconstriction, and asthma "inducers" which cause inflammation.)  For more information about asthma triggers, go to Key Point 1.

When airways are already inflamed, they're more sensitive to allergens and irritants.  So a person with inflamed airways is more likely to suffer asthma symptoms.  We don't know why people first get inflamed airways, but there does seem to be a genetic factor to it.  That means you can be born with the tendency or predisposition to have asthma, but it does not mean you definitely will get it. 

Asthma varies from person to person, that is, not everyone reacts to the same triggers, suffers the same symptoms, nor suffers them at the same intervals (i.e., daily, weekly, etc.).  Further, each individual's symptoms can vary from one time to another, and their frequency can also vary. Asthma often begins in childhood, though there is also "adult onset asthma." 

When the symptoms of asthma become very strong, we say the person is having an "asthma attack."  In a severe asthma attack, a person may have so much trouble breathing that emergency treatment is needed.  This can cause serious damage to the body.  In fact, according to the American Academy of Allergy Asthma & Immunology about 5000 people per year die from very severe asthma attacks.

The National Institutes of Health (NIH) says about fifteen million Americans have asthma, including close to five million children.  The Asthma and Allergy Foundation of America puts the total figure nearer twenty million.  In children, more boys than girls have asthma; in adults, the situation is reversed.  Although asthma is a problem among all races in America, the NIH says African-Americans have more asthma attacks, are more likely to be hospitalized for it, and are more likely to die from it.

There are many things we don't know about asthma – including how to cure it.  But we do know how to treat it so we can alleviate its effects and allow people to live with few or no asthma symptoms.  For more information about treating asthma, go to Key Point 3.