Asthma is the common chronic inflammatory disease of the airways characterized
by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm.
Symptoms include wheezing, coughing, chest tightness, and shortness of breath.
Asthma is clinically classified according to the frequency of symptoms, forced
expiratory volume in 1 second (FEV1), and peak expiratory flow rate.
It is thought to be caused by a combination of genetic and environmental factors.
Treatment of acute symptoms is usually with an inhaled short-acting beta-2 agonist
(such as salbutamol).
Symptoms can be prevented by avoiding triggers, such as allergens and irritants, and by
inhaling corticosteroids. Leukotriene antagonists are less effective than corticosteroids
and thus less preferred.
Its diagnosis is usually made based on the pattern of symptoms and/or response to
therapy over time. The prevalence of asthma has increased significantly since the 1970s.
As of 2010, 300 million people were affected worldwide.
In 2009 asthma caused 250,000 deaths globally. Despite this, with proper control of
asthma with step down therapy, prognosis is generally good.