Contraceptive pills taken within 72 hours after sex are emergency contraceptive pills, which may cause normal menstruation to be delayed for about 3-10 days, the specific delay time varies from person to person. If the delay time is more than 10 days, you need to go to the hospital in time for examination, suspecting that there is a possibility of contraceptive failure. Emergency contraceptive pills belong to the progesterone class of drugs, which has the effect of resisting implantation, so as to achieve the purpose of contraception. The drug content of emergency contraceptive pills is very high, will affect the normal ovarian secretion function, easily cause vaginal bleeding and delayed menstruation and other symptoms, which is a normal side effect of the drug is not important. Emergency contraceptive pills are easy to use, can be prepared for a moment of need, but not easy to use too often, so as not to cause endocrine disruption, serious cases will cause amenorrhea affecting the normal health of women.