If there is sexual intercourse on the 1st day of menstruation, the possible clinical consequences are chronic inflammation of the cervix, infection in the uterine cavity, and even pelvic inflammatory disease. In addition, due to the stimulation of coitus, the uterus will contract, resulting in the closure of the mouth of the uterus, and menstrual blood will flow into the pelvis in the fallopian tube, causing endometriosis. To deal with this, you can boil hot brown sugar water and drink it for 3 consecutive days, so that the menstrual blood can be discharged smoothly down the cervix to avoid reflux. You can also take anti-inflammatory drugs for 2 days, mainly to prevent the infection of pathogenic bacteria, so as not to cause inflammation.