48 year old man left side partial back pain mostly refers to the left side of the adult waist pain, common causes are exertion, trauma, lumbar muscle strain, kidney stones, lumbar intervertebral disc herniation and so on. 1. Exhaustion: prolonged stooping work, weight-bearing activities, overworked body, lumbar muscle lactic acid accumulation caused by pain, rest can be relieved. 2. Trauma: due to the work of improper posture sprain waist or fall, fall from a height and other reasons, caused by the left side of the lumbar soft tissue injury or lumbar spine fracture, resulting in lumbar pain. 3. Lumbar muscle strain: due to prolonged weight bearing, stooping, improper posture, causing aseptic inflammation of the muscles and fascia of the lumbar back, the common symptoms are lumbar pain, difficulty in bending. 4. Kidney stones: due to the blockage of the ureter after the stone, causing local damage, irritation, lumbar pain, usually more intense pain. 5. Lumbar intervertebral disc herniation: due to advanced age, improper posture, trauma and other reasons, resulting in disc degeneration, the nucleus pulposus protrudes backward and compresses the nerve root inside the dural sac, and lumbar pain can occur. Causes of left-sided lumbar pain in adults are more, may also be related to lumbar back fasciitis, tumor, ankylosing spondylitis, bone tuberculosis and other diseases, if the symptoms continue to be unrelieved, it is recommended to consult a doctor in time, to clarify the cause of the disease, and to carry out targeted treatment.