Shortness of breath is a symptom in itself, which may be caused by asthma, pneumothorax and other diseases, and is characterized by increased respiratory rate, which may be accompanied by dyspnea and other manifestations. 1. Asthma: Asthma attacks mostly occur after exposure to allergens, and its shortness of breath symptoms are mainly characterized by episodes of expiratory dyspnea, accompanied by rales. Patients feel that breathing is laborious, the breathing rate increases, severe asthma patients will also appear to slow down the number of breaths, or even breathing stops. 2. Pneumothorax: Its symptoms of shortness of breath are usually characterized by inspiratory or respiratory dyspnea with hissing sounds. Pneumothorax is mostly caused by car accidents or knife wounds that lead to rupture of the patient’s chest opening, air enters the lungs and causes the diaphragm to swing abnormally, which affects normal gas exchange, and the patient’s thoracic cavity gradually increases in size along with respiration, which causes respiratory distress and requires immediate ventilatory treatment. Shortness of breath may also be seen in pneumonia, heart failure, emotional excitement, strenuous exercise and other people, if the persistence can not be relieved, it is recommended to consult a doctor in a timely manner, under the guidance of the doctor to identify the causes of active treatment, so as not to delay the condition.