The causes of asthma are as follows: 1, allergies: such as pollen, special substances in the air, mites, formaldehyde, etc.; 2, infections: such as viruses, bacteria, mycoplasma, etc.; 3, food: younger children, easy to food-induced asthma, with the growth of age, the incidence of the chances of can be reduced; 4, climate change: winter, spring, or fall and winter, asthma attacks are more frequent; 5, psychiatric factors: nervousness, anxiety, fear, when the asthma is prone to attacks; 6, exercise: some patients with exercise-based asthma; 7, women’s physiological and gestation may trigger or aggravate asthma; 8, medications: such as cardiac glycosides and aspirin easily caused asthma.