Soreness on one side of the buttocks may be caused by physiological reasons, or pathological reasons such as pyriformis syndrome, lumbar disc herniation and so on. 1. Physiological reasons: it is possible that long-term sedentary or sitting posture is incorrect, resulting in one side of the buttock muscle pressure for a long time, may cause the pressure side of the buttock soreness. 2. Pathological causes (1) Piriformis syndrome: it may be due to indirect violence, such as sprains, repeated squatting and other actions and chronic strain, resulting in injury to the piriformis muscle, when the piriformis muscle is stimulated by cold or compression of the sciatic nerve and cause pain in the buttocks and legs on one side. (2) Lumbar intervertebral disc herniation: it may be the degeneration of lumbar intervertebral disc, or long-term weight bearing, resulting in excessive pressure on the lumbar intervertebral disc, cold or sudden rise in pressure on the intervertebral disc and other factors leading to intervertebral disc herniation, compression of the nerves, but also one side of the buttocks will appear pain. It is recommended to consult a doctor to identify the cause of the pain on one side of the buttocks and to treat it with targeted treatment or therapy.