Pain on the left side of the body may be caused by physiological factors, cervical spondylosis, urinary stones and other diseases. 1. Physiological factors: pain on the left side of the body should first determine whether there is trauma. If there is no trauma, the pain may be caused by prolonged postural malposition or chronic muscle strain, and engaging in heavy physical activities. 2. Cervical spondylosis: It may be caused by cervical spondylosis, which is more common when there are serious hyperplasia, bone spurs or herniated cervical discs in the cervical spine that affect the nerves to be compressed, thus causing pain on the left side of the body. 3. Urinary stones: when the left side of the kidney, ureteral stones, there may be left lumbar pain and discomfort, which may also be accompanied by hematuria, renal percussion pain. When there is infection, there may also be frequent urination, urinary urgency, urinary pain and other clinical manifestations. These are only some of the common causes. If the symptoms persist or recur, you should consult a doctor. After a clear diagnosis, follow the doctor’s instructions to standardize the treatment.