After the menstrual period is over and the menstrual blood is completely clean and there is no brown discharge, then you can have sex (coitus). Clinically, for health reasons, it is recommended that women should have sex when their menstrual period is completely over. If they have sex during their menstrual period, it is easy for the cervix to open up and for the menstrual blood to flow backward, which can lead to pelvic inflammatory disease, endometriosis, and vaginitis, etc. If they have sex right after their menstrual period, some women may still have a small amount of menstrual blood left in the genital tract. If you have sex right after your period, some women may still have a small amount of menstrual blood left in their reproductive tracts, and having sex at this time may bring in pathogenic bacteria, which can cause vaginitis and other infectious lesions. It is recommended to wait about three days after the end of menstruation, after the menstrual blood is completely clean before having sex. If you feel uncomfortable after sex, you should consult a doctor for further treatment or therapy.