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Asthma symptoms affect an estimated 26 million Americans and are one of the leading causes of absences from work and school. Although asthma has no cure, effective treatments are available; the condition can be best managed by seeing an allergist. Learn about how asthma can affect children and pregnancies.


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What causes asthma?

Asthma is a chronic inflammation and obstruction of the bronchial tubes, the airways that allow air to enter and leave the lungs. People often think of asthma in terms of episodes or attacks. Actually, someone with asthma always has it, but the symptoms may not appear until triggered by something that provokes a response in the body, such as exercise, cold air, stress, illness, irritants in the air, certain medications or an allergen.

Allergens are substances that cause no problem in most people but produce an abnormal reaction in some. When someone who is sensitive to an allergen is exposed to it, his or her immune system “sees” it as a foreign substance and releases chemicals to deal with it. For people with asthma, those chemicals can cause an asthma attack — meaning that their airways become constricted, they find it difficult to breathe and they may experience coughing or wheezing.

Common Asthma Triggers

  • Outdoor allergens, such as pollens from grass, trees and weeds
  • Indoor allergens, such as pet dander, dust mites and mold
  • Irritants in the air, such as smoke, chemical fumes and strong odors
  • Exercise (although people with asthma can benefit from some exercise)
  • Stress
  • Weather conditions, such as cold air or extremely dry, wet or windy weather

Colds, flus and other illnesses

  • Viral respiratory infections, including the flu, are the leading cause of acute asthma attacks. (Surprisingly, bacterial infections, with the exception of sinusitis, do not bring about asthma attacks.)
  • Some people with heartburn can have asthma symptoms when stomach acid backs up into the esophagus.

Drugs and food additives

  • Up to 20 percent of people with asthma are sensitive to aspirin, products that contain aspirin or other over-the-counter pain relievers, such as ibuprofen. People with asthma should discuss with their allergist whether these products should be avoided.
  • Beta blockers, which often are prescribed for high blood pressure, glaucoma, migraine headaches and angina, can cause bronchospasm, an airway constriction. Patients with asthma should consult an allergist about the use of these medications.
  • Food additives rarely trigger asthma. The most common food trigger for asthma is sulfite, a preservative used in such products as frozen potatoes and some beers and wines.

Asthma vs. Allergic Disease

Asthma is a chronic condition; allergies are just one of the factors that can trigger an asthma attack. Not all people with asthma are allergic, and there are many people who have allergies but do not have asthma.

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