After menstruation, it takes about three days or more before you can have sex. Theoretically speaking, three days after the end of menstruation, the residual blood in the vagina can be cleared, at this time it is possible to have sex, and it will not have too much effect on the body. However, there are some women who may not be able to finish their menstrual period and may experience vaginal bleeding again at any time after their period has ended, and they should actively cooperate with their doctor for treatment at this time. Women should not have sex when their menstruation has just ended, because the wound of endometrial stripping has not fully recovered, if they have sex too early, it may cause the tiny wound of endometrium to bleed again under the effect of sexual stimulation, resulting in prolongation of menstruation, and it is easy to bring pathogenic microorganisms into the vagina and uterine cavity, which may cause infectious diseases in women. Therefore, most women can have sex three days after the end of menstruation. Women are advised to pay more attention to the perineal area and change their underwear regularly.