The most common reason for the soreness of the waist the next day after coitus is due to kidney deficiency, Chinese medicine believes that the waist is the capital of the kidneys, the kidneys hide the essence of the waist, the waist is lost, there will be pain in the waist. After coitus under normal circumstances should not appear back pain, if frequent coitus back pain, and at the same time there is a white face zygomatic red, five heart heat, short urine, hands and feet, etc., is due to the kidney yin deficiency caused by the treatment should be nourishing the kidney yin. If there is soreness in the waist after intercourse, and at the same time there is coldness in the waist and back, fear of wind, cold air, limbs are not warm, urine is clear and long, and loose stools, it means that it is due to kidney yang deficiency, and the treatment is based on warming and tonifying the kidney yang.