Sex during menstruation is harmful to the body, mainly the following points: First, it will affect the amount of menstruation, due to the stimulation of sexual life will lead to uterine spasm, contraction, will cause an increase in the amount of menstruation, prolonged periods, serious can cause haemorrhage leading to anemia. Second, increase the probability of inflammatory infections, during menstruation, resistance is reduced, the uterine mouth is not completely closed, when sex, bacteria can easily enter the uterine cavity through the vagina uterine mouth, will cause infection of the endometrium and inflammation of the fallopian tubes, the subsequent recovery of the body, menstruation and pregnancy will have an impact. Thirdly, sex during menstruation can also affect the cervix and vagina, increasing the probability of cervicitis and vaginitis. Fourthly, it also has an effect on the male genitalia, which can easily cause inflammation of the male genitalia.