There is no fast way to relieve cramps on the back side of the thigh, mainly targeted to take general treatment, physical therapy, medication and so on. 1. General treatment: in the back of the thigh cramp, to temporarily avoid activities that can reduce the stimulation of the thigh muscles, at the same time, appropriate massage and hot compresses on the thigh area, generally can relieve the muscle membrane as well as muscle spasm symptoms. 2. Physical therapy: If the symptoms of cramps last for a long time and cause obvious pain, you can also take local physical therapy, such as microwave therapy, which can improve the blood circulation of the back side and relieve the symptoms of cramps. 3. Medication: Cramps on the back of the thighs may be caused by calcium deficiency, which requires supplemental calcium supplements such as calcium carbonate and calcium lactate as prescribed by the doctor. If the symptoms of cramps at the back of the thigh continue to be unrelieved, you should go to the hospital in time and cooperate with the doctor to take treatment or therapy.