Once sitting on the toilet leg numbness, generally there are two possibilities: the first, due to the sciatic nerve pressure; the second, the existence of lumbar disc herniation. For the first case, because the sciatic nerve travels in the back of the thigh, so in the use of the toilet, the nerve will be part of the pressure, if the time is longer will affect the blood supply of the nerve, so there will be numbness of the nerves, that is, manifested as numbness of the legs, this situation can be relieved by standing up or reduce the time to sit on the toilet. Another situation is the existence of lumbar disc herniation, if sitting on the toilet, due to the posture of the body forward will lead to lumbar disc herniation aggravation, so cause numbness in the legs. In this case, the orthopedic department should be consulted as soon as possible and lumbar spine MRI should be performed to clarify the nature of the disease.