Asthma is a common chronic (chronic (medicine)) inflammatory disease of the airways (bronchi) characterized by variable and recurring symptoms, airflow obstruction, and bronchospasm. Symptoms include wheezing, cough, chest tightness, and shortness of breath.

Medicines such as inhaled short-acting beta-2 agonists (Beta2-adrenergic agonist) may be used to treat acute attacks. Attacks can also be prevented by avoiding triggering factors such as allergens or rapid temperature changes and through drug treatment such as inhaled corticosteroids. Leukotriene antagonists are less effective than corticosteroids, but have fewer side effects. The monoclonal antibody omalizumab is sometimes effective.

It affects 7% of the population of the United States, 6.5% of British people and a total of 300 million worldwide. Citation neededdate=May 2010 Asthma causes 4,000 deaths per year in the United States and 250,000 deaths per year worldwide. Prognosis is good with treatment.

Although asthma is a chronic (chronic (medicine)) obstructive (obstructive lung disease) condition, it is not considered as a part of chronic obstructive pulmonary disease as this term refers specifically to combinations of bronchiectasis, chronic bronchitis, and emphysema. Unlike these diseases, the airway obstruction in asthma is usually reversible; however, if left untreated, asthma can result in chronic inflammation of the lungs and irreversible obstruction.Citation neededdate=May 2010 In contrast to emphysema, asthma affects the bronchi, not the alveoli. Public attention in the developed world (developed country) has increased recently because of its rapidly increasing prevalence, affecting up to one quarter of urban (urban area) children.