Left side back pain hurts with inhalation, and it is considered to be related to pleural inflammation, rib fracture, myofibrillitis, frozen shoulder and other factors. 1. Pleural inflammation: when pleurisy occurs, a small amount of pleural fluid usually gathers here, and when the pressure in the chest cavity drops during inhalation and the lung tissue expands, the dirty pleura and the wall pleura will be friction and stimulation, and the left side back pain will appear. 2. Rib fracture: If a stable fracture occurs, although there is no obvious displacement, the broken end of the fracture may rub with breathing activities, resulting in left-sided back pain. 3. Myofibrillitis: cold, exertion and other factors can cause aseptic inflammation of the muscles. Muscle contraction can occur during inhalation, leading to pain symptoms. At this time, conservative treatment through physical therapy, heat and other ways to relieve the symptoms. 4. Frozen shoulder: Inflammation of the shoulder muscles will not only cause pain in the local tissues, but also lead to restricted movement of the joints and arms. Sometimes inhalation causes muscle contraction, can also lead to left back pain after inhalation. When the left side of the back pain inhalation pain symptoms, it is recommended to go to the hospital timely examination, clear causes, and then targeted treatment.