The common causes of sudden pain in the left side of the lumbar region are as follows: first, acute injury, commonly after strenuous exercise or sudden accidents, resulting in acute strains and sprains of the left lumbar muscle, and fractures of the transverse processes of the lumbar spine, resulting in corresponding severe pain symptoms and functional impairment. Secondly, pathological fracture of the lumbar spine can be seen, due to the previous existence of osteoporosis, bone tumor, bone infection causing bone destruction in the lumbar spine, which can easily cause compression fracture of the lumbar spine under slight external force, resulting in sudden pain. Third, small joint disorders of the lumbar spine, commonly seen in violent sneezing or violent coughing, can lead to misalignment and disorders of the small joints of the lumbar spine, resulting in sudden pain and dysfunction, which need to be treated by traction and massage. Fourth, internal system diseases, such as urinary stones, due to stones suddenly stuck in the ureter, resulting in sudden and severe pain.