OverviewAsthma is a disease in which inflammation of the airways causes airflow into and out of the lungs to be restricted. The muscles of the bronchial tree become tight and the lining of the air passages swells, reducing airflow and producing the characteristic wheezing sound. This is known as an asthma attack, which can occur as an allergic reaction to an allergen or other substance (acute asthma), or as a part of a complex disease cycle which may include reaction to stress or exercise (chronic asthma).
Update Date 4/21/2015
Updated by: Neil K. Kaneshiro, MD, MHA, Clinical Assistant Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.