Asthma is a description of symptoms, and it is a compensatory manifestation caused by severe cough for a long time or severe exercise leading to alveolar and bronchial spasm and decreased oxygen exchange function of the lungs. Generally, the onset is slow and the relief is rapid after rest. Long-term appearance may be a precursor to emphysema.

Asthma is an allergic disease. There are premonitory symptoms before the attack, such as sneezing, runny nose, cough and chest tightness. Generally, due to the stimulation of smoke, foreign bodies and cold air, the trachea and bronchus contract violently and secrete a large amount of secretions, which leads to shortness of breath, and a large amount of secretions block the trachea and bronchus, making it difficult to breathe, and even cyanosis and shock may occur. Need drug relief.