Chest pain after quitting smoking is mainly caused by withdrawal reactions. Symptoms similar to the flu will appear about 1-2 weeks after quitting, which also tend to cause chest tightness and chest pain. In most cases, it lasts for about 10 days, and then it will slowly decrease or disappear. At this time, you should pay attention to rest and diet, and try to avoid overexertion. If the chest pain is more severe and does not decrease after a period of time, you should also consider that it is caused by other reasons. If you have respiratory disease or heart disease, such as lung cancer, tuberculosis, pneumonia or myocardial ischemia, you need to go to the hospital for appropriate tests to rule out these diseases.