There are many reasons for left subcostal pain left back pain, and the common ones are intercostal neuritis, pleurisy, coronary heart disease and so on. 1. Intercostal neuritis: inflammatory reaction caused by various reasons, manifested as pain in the area innervated by the intercostal nerve, consistent with the intercostal nerve course, was distributed in a band. If the left intercostal neuritis is manifested as left subcostal pain and left back pain. 2. Pleurisy: a series of inflammatory reactions produced by various pathogenic bacteria invading the pleura, the pain is mostly located in the part of pleurisy, which can appear as left subcostal pain and left back pain, often accompanied by chest tightness, cough and other symptoms. 3. Coronary heart disease: atherosclerosis of the coronary arteries causes narrowing or occlusion of the lumen, resulting in myocardial ischemia and hypoxia, chest pain. It is mostly located in the middle or left side of the chest and may radiate to the left back. It is often accompanied by chest discomfort and dyspnea. The left side of the rib cage pain left back pain is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, standardize the treatment.