Sudden feeling of breathlessness may be caused by psychological factors, asthma, myocardial infarction and so on. 1. Psychological factors: mental tension, anxiety, depression and other bad emotions may lead to poor breathing. It is recommended to learn to relax yourself and take deep breaths, which can help improve the situation. 2. Asthma: Sudden exposure of asthma patients to certain allergens may cause asthma attacks, resulting in poor breathing. It is recommended to find and get rid of the allergens, and give antihistamines (e.g., loratadine, levocetirizine, etc.) and bronchodilators (e.g., salbutamol, etc.) if necessary, which can help relieve the symptoms. 3. Myocardial infarction: Myocardial infarction patients feel breathlessness, which is mainly considered to be related to impaired cardiac function caused by myocardial infarction. Besides, ischemia caused by myocardial infarction may also lead to dyspnea. Suddenly feel breathless for many reasons, can also be seen in pulmonary embolism and other diseases, it is recommended to improve the relevant laboratory tests in time, clear causes, targeted and rational standardized treatment.