The left chest sometimes hurts and sometimes doesn’t hurt, which can be seen in chest wall lesions, heart disease, lung disease, etc. 1. Chest wall lesion: in the early stage of simple rib fracture, the pain is not obvious when breathing normally, and the chest pain can be felt when coughing or deep breathing. It can also reoccur for a short time after the pain of costochondritis is relieved. Intercostal neuralgia, if the cause persists, can reoccur after the pain has subsided. 2. Heart disease: angina pectoris and coronary artery disease can be caused by coronary artery spasm resulting in insufficient blood supply to the myocardium in a short period of time and paroxysmal pain. Cardiac neurosis, such as fatigue, emotional stress, etc. can be triggered again. 3. Lung diseases: pleurisy and lung infections, etc. with the evolution of the course of the disease will appear pain sometimes and sometimes not. The left chest sometimes hurts and sometimes doesn’t, and patients are advised to go to the hospital in time to avoid delaying the condition.