What causes asthma?

Christopher M. Webber, MD
Allergy & Immunology
Asthma is caused when inflammation is triggered in the lungs, which causes symptoms that include airway swelling, mucus production and a pinching or clamping down of muscles around the lungs. This is an actual immune system inflammation. To help this make sense, think of a time that you cut yourself: You have the cut itself, which will eventually scab over, and you have the surrounding area that is red, swollen and painful. This is true inflammation, which is caused by the immune system rushing to destroy any bacteria or dirt, for example, that surrounds the cut.

Now imagine this happening in your lungs. First, inflammation causes airway swelling and mucus production inside the lung. This can cause shortness of breath, oxygen problems, chest tightness and most asthma symptoms. Second, inflammation causes problems with the muscles that surround the airway. Muscles surround the airway of the lungs like paper towels around the cardboard center. Inflammation causes these muscles to close off or pinch down all of a sudden. This also causes wheezing, chest tightness and shortness of breath; this is usually the tipping point for an asthma attack.
Paul M. Ehrlich, MD
Allergy & Immunology
Dr. Anthony Gagliardi, a pulmonologist at St. Vincent's Hospital in New York, says that the study of asthma "is the study of one." That is, asthma describes a set of symptoms -- also known as "asthma syndrome," -- that may be triggered by many allergic or environmental causes, or bacterial infection. We have to solve the mysteries, and treat them, one at a time. Although no single "asthma gene" has been discovered, asthma does seem to run in families. Asthma also tends to occur more often in families that have a history of other allergies, and in fact, many patients have both asthma and allergies of the nose, eyes, or skin.

If a parent or sibling has asthma, there is greater likelihood of early onset asthma, which means it develops early in childhood. If the parents smoke, particularly the mother, it increases the incidence of asthma at a young age. Still, asthma may start at any age. Attacks are triggered by substances to which children are allergic. For example, a patient with cat allergy develops an asthma attack when he visits a home with cats.
Asthma Allergies Children: A Parent's Guide

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Asthma Allergies Children: A Parent's Guide

Asthma and allergies are at epidemic proportions. It doesn't have to be that way. Two experienced pediatric allergists tell everything a conscientious parent needs to know about these conditions,...
Sam Pejham, MD
People with Asthma have very sensitive airways that respond to different triggers.  These triggers cause the airways to become inflamed and become narrowed causing the asthma symptoms.  The reason why some people get asthma and some don't is still largely unknown, but genetics, lung infections, and environmental factors have been linked to cause asthma in some individuals.
Triggers for asthma include: air pollution, smoking, pollen, respiratory infections, allergies, exercise, weather changes, etc.

The exact cause of asthma is unknown, but researchers believe that a combination of factors including genetics and environmental exposures together cause this condition. Typically, asthma begins in childhood, but it can start at any age. People with a family history of asthma or who have allergies are at increased risk for asthma. In people with allergies, the allergic response can make you more sensitive to allergens in the air (such as dust mites, cockroaches, pet dander, tobacco smoke) and can trigger an asthma attack.

Doctors aren't sure what causes asthma, but it probably comes from a combination of inherited and environmental triggers. If you are genetically prone to asthma, an attack can be brought on if you feel stressed, breathe cold air or cigarette smoke, have a cold, or inhale allergens like mold or pollen.

Asthma can also be caused by allergies. Allergens such as pet dander can swell the passages in the nose and the airways to the lungs, causing tightness of breath and wheezing.

Another possible cause of asthma is the "hygiene hypothesis." Some scientists think that modern advancements in personal hygiene have limited children's exposure to common infections, affecting the development of their immune systems. They may be more prone to developing allergies and asthma because they have not had the chance to develop immunity to common allergens.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.