Asthma

Asthma is a common long-term inflammatory disease of the airways of the lungs.^[3] It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms.^[10][11]Symptoms include episodes of wheezing, coughing, chest tightness, and shortness of breath.^[2] These may occur a few times a day or a few times per week.^[3] Depending on the person, they may become worse at night or with exercise.^[3]

Asthma is thought to be caused by a combination of genetic and environmental factors.^[4] Environmental factors include exposure to air pollution and allergens.^[3] Other potential triggers include medications such as aspirin and beta blockers.^[3] Diagnosis is usually based on the pattern of symptoms, response to therapy over time, and spirometry.^[5] Asthma is classified according to the frequency of symptoms, forced expiratory volume in one second (FEV1), and peak expiratory flow rate.^[12] It may also be classified as atopic or non-atopic, where atopy refers to a predisposition toward developing a type 1 hypersensitivity reaction.^[13][14]

There is no cure for asthma.^[3] Symptoms can be prevented by avoiding triggers, such as allergens and irritants, and by the use of inhaled corticosteroids.^[6][15] Long-acting beta agonists (LABA) or antileukotriene agents may be used in addition to inhaled corticosteroids if asthma symptoms remain uncontrolled.^[16][17] Treatment of rapidly worsening symptoms is usually with an inhaled short-acting beta-2 agonist such as salbutamol and corticosteroids taken by mouth.^[7] In very severe cases, intravenous corticosteroids, magnesium sulfate, and hospitalization may be required.^[18]

In 2015, 358 million people globally had asthma, up from 183 million in 1990.^[8][19] It caused about 397,100 deaths in 2015,^[9] most of which occurred in the developing world.^[3] It often begins in childhood.^[3] The rates of asthma have increased significantly since the 1960s.^[20] Asthma was recognized as early as Ancient Egypt.^[21] The word "asthma" is from the Greek ἅσθμα, ásthma, which means "panting".^[22]