The causes of asthma mainly include endogenous and exogenous factors, endogenous factors are genetic factors, exogenous factors are mainly related to allergens, as follows: 1, endogenous factors: most of them are genetic and physical factors, asthma is a disease related to genetics, which is more complex and is a multi-gene genetic tendency, on the basis of endogenous factors encounter allergens, infections, sports, as well as drugs, chemical agents, mental stimulation and other triggers, which can make The small blood vessels of the tracheobronchial mucosa are dilated and congested, the exudation increases, the secretion in the lumen increases, and the bronchial tubes become spasmodic, the airflow is restricted, and asthma occurs or is aggravated.2. External factors: common allergens such as indoor dust mites, pollen, and some animal fur can also induce, and then aspirin, which is the most common kind of drug that induces asthma. In addition, environmental factors are also contributing factors.