The most common cause of bronchial asthma is inhalants, which are mainly found in daily life, such as dust mites, pollen, fungi, and some irritating and toxic gases, all of which may irritate the airways and cause asthma. Infections are closely related to the occurrence of asthma, and respiratory infections such as viruses, bacteria, and mycoplasma can all trigger asthma. Additionally, certain specific foods, such as fish, shrimp, crab, milk, and eggs, may cause asthma in certain groups of people. Factors such as the patient's mental state, changes in the climate, and intense exercise are also possible causes of bronchial asthma. These are the most common causes of bronchial asthma onset.