Asthma has more causes and belongs to metabolic diseases, the common causes are as follows: 1, genetic variation: asthma is affected by genes and is a disease with a tendency to genetic variation; 2, allergic factors: is the most important factor in the occurrence of asthma, such as eating meat, eggs, milk allergy, which in turn leads to the occurrence of bronchial asthma; 3, infection factors: such as bacterial, viral, fungal infection, prone to bronchial asthma; 4, exercise: exercise can trigger bronchial asthma; 5, other: asthma can occur during menstruation in some female patients.