Asthma

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Overview, Causes, & Risk Factors

Asthma is a disease in which inflammation of the airways causes airflow into and out of the lungs to be restricted. When an asthma attack occurs, the muscles of the bronchial tree become tight and the lining of the air passages swells, reducing airflow and producing the characteristic wheezing sound. Mucus production is increased.

Most people with asthma have periodic wheezing attacks separated by symptom-free periods. Some asthmatics have chronic shortness of breath with episodes of increased shortness of breath. Other asthmatics may have cough as their predominant symptom. Asthma attacks can last minutes to days, and can become dangerous if the airflow becomes severely restricted.

In sensitive individuals, asthma symptoms can be triggered by inhaled allergens (allergy triggers), such as pet dander, dust mites, cockroach allergens, molds, or pollens. Asthma symptoms can also be triggered by respiratory infections, exercise, cold air, tobacco smoke and other pollutants, stress, food, or drug allergies. Aspirin and other non-steroidal anti-inflammatory medications (NSAIDS) provoke asthma in some patients.

Asthma is found in 3-5% of adults and 7-10% of children. Half of the people with asthma develop it before age 10, and most develop it before age 30. Asthma symptoms can decrease over time, especially in children.

Many people with asthma have an individual and/or family history of allergies, such as hay fever (allergic rhinitis) or eczema. Others have no history of allergies or evidence of allergic problems.