Hidden pain in the left side of the waist can be considered physiological factors, lumbar muscle strain, lumbar degenerative changes, lumbar disc herniation, internal diseases and other factors. 1. Physiological factors: due to cold, women’s menstruation and other physiological reasons, may trigger pain and discomfort in the lumbar region, appropriate rest or local heat can be relieved. 2. Lumbar muscle strain: due to long-term bad posture or excessive fatigue and other factors, can cause aseptic inflammation of the lumbar muscles, resulting in lumbar muscle strain, manifested as one side of the spinous processes or bilateral pain and stiffness, can be gradually relieved by improving bad habits, pay attention to rest and other ways. 3. Degenerative changes of lumbar vertebrae: mostly seen in the elderly, with age, there will be degeneration and osteophytes of lumbar vertebrae, which will also cause one or both sides of the lumbar pain. 4. Lumbar disc herniation: the typical symptom of lumbar disc herniation is lumbar pain, in addition to one or both sides of the lumbar pain, most of them may also be accompanied by lower limb pain and numbness and other neurological symptoms. 5. Internal diseases: for example, chronic nephritis, kidney tumors, etc., can also cause pain and discomfort in the lower back. There are many other causes of lumbar pain and discomfort, which require timely hospitalization to determine the cause and targeted treatment.