The causes of left-sided lumbar pain are commonly the following: 1, lumbar muscle strain: prolonged fixed posture or overexertion can cause left-sided lumbar muscle strain, and the patient will have clinical symptoms of left-sided lumbar pain. However, the pain is generally not serious and will not affect basic life. 2. Lumbar disc herniation: can compress the nerve, resulting in painful symptoms on the left side of the back, and will be accompanied by limited lumbar movement. 3. Left lumbar transverse process fracture: can cause severe and persistent painful symptoms on the left side of the back, requiring bed rest, in order to make clinical symptoms to be gradually relieved in about three weeks. Therefore, if pain occurs on the left side of the lumbar region, timely diagnosis and treatment are necessary to relieve clinical symptoms in a short period of time. Patients should pay attention to the protection of the lumbar region in general to avoid the development of several diseases mentioned above and to prevent the occurrence of symptoms.