Sudden cramp-like pain in the lower back may be caused by muscle spasms, acute injuries, herniated lumbar discs and so on. In addition physiological causes should not be ignored. 1. Muscle spasms: If the patient’s waist is often cold or there is a lack of calcium, it will cause muscle spasms in the lumbar region, resulting in sudden cramps like pain in the lower back, and should pay attention to warmth, massage, or calcium supplementation for treatment. 2. Acute injury: If there is a sprain or impact in the waist, it may cause muscle or ligament tearing injury and cramp-like pain, and should pay attention to bed rest to restore the injured area. 3. Lumbar disc herniation: due to the herniated nucleus pulposus will cause nerve root compression or cauda equina acute compression, causing sudden cramp-like pain. Sudden cramp-like pain in the lumbar region may also have other causes, after excluding physiological causes, it is recommended that the patient should go to the hospital in a timely manner, a clear diagnosis and treatment.