Left back pain can be caused by lumbar dorsal myofasciitis, lumbar degenerative diseases, nerve compression diseases, urinary tract diseases and other diseases. 1. Myofasciitis of the lumbar back: injury to the muscles and other soft tissues of the left lumbar region, or myofasciitis of the lumbar region, often caused by factors such as prolonged desk work, sedentary work, and prolonged periods of time in a cold and humid environment, and the occurrence of aseptic inflammation in the muscles of the left lumbar back, which can lead to pain in the left lumbar region, and symptoms of limited activity. 2. Lumbar degenerative diseases: degenerative lumbar scoliosis, lumbar spondylolisthesis, arthritic hyperplasia, lumbar spondylolisthesis and other diseases, which can cause left lateral curvature of the spine, aseptic inflammation of the left side of the joints and left side of the muscle, and lead to the left lumbar pain and discomfort symptoms. 3. Nerve compression diseases: lumbar spinal stenosis, disc herniation and other diseases can lead to the left side of the sinus nerve compression, causing the left side of the lumbar numbness, pain and other discomforts, and can be radiated to the lower limbs and other areas. 4. Urological diseases: left kidney tumor, pyelonephritis, left urinary stones, due to its location near the left side of the waist, the onset of pain in the left side of the waist symptoms. There are many reasons for left lower back pain, if it is difficult to relieve, you should consult a doctor in time, under the guidance of specialists to actively carry out appropriate treatment, which will help to relieve the pain and other uncomfortable symptoms as soon as possible.