The causes of pain in the ribs under the left breast are as follows: first, it may be caused by inflammation of the ribs, if the pain is inflammatory, there is a more pronounced pain at the pressure when the ribs are pressed, it is recommended to go to the hospital in time to take pictures to confirm the diagnosis and determine the inflammation site for treatment. Second, it may be caused by local injury to the ribs, when the muscles and nerves around the ribs are damaged will cause pain, such cases can be treated with painkillers, such as slow-release type of painkillers ibuprofen, etc. At the same time, pay attention to the warmth of the injured parts to prevent cold. You can also apply local heat, massage, infrared light irradiation, etc. to promote local blood circulation and promote the recovery of the injured tissue. Third, the cause of rib fracture should be considered. If it is a rib fracture, it should be fixed by incision in time to prevent the fracture end from being displaced and affecting the surrounding tissues.