It is forbidden to have intercourse when you are on your period. First of all, because at this time the entire pelvis is in a state of congestion, coitus is easy to cause hemorrhage caused by the prolongation of menstruation. Secondly, the cervical opening is open, bacteria can easily travel up the vagina to the cervical opening, through the cervix to the uterine cavity, or even the entire pelvis, causing a series of gynecological inflammation, such as endometritis, adnexitis, pelvic inflammatory disease, etc., the patient will have abdominal pain, lumbar acidity, falling, and in severe cases, the patient will cause fever and other symptoms. Therefore, clinically, it is recommended that patients have intercourse three days after the menstrual period is completely clean.