Intercourse on the 5th day of menstruation has an effect on the body, it is best not to have intercourse. The uterus is in an open state on the 5th day of menstruation, and the shedding of endometrium and other substances will be discharged out of the body slowly through the cervix and vagina, and the menstruation is not completely over, and there has been the appearance of blood, and if you have intercourse at this time, it will lead to bacterial growth, which will lead to a variety of disease reactions, such as vaginitis and cervicitis. After coitus will cause stimulation of the uterus, upstream infection will appear endometriosis, it is best not to coitus in the menstrual period. After coitus, you should pay attention to timely observation of the body, see whether there is abdominal distension and pain, vulvar itching, there are abnormal problems should be timely medical treatment, so as not to lead to the disease becomes more serious.