The emergency contraceptive pill works on the 11th day of your period. A woman’s normal menstrual period is usually about 3 to 7 days, so the 11th day of menstruation means the 14th to 18th day of menstruation, which should belong to the ovulation period. If you take the pill for contraception during ovulation, then you must take the emergency contraceptive pill. If you use short-acting oral contraceptives and long-acting contraceptives, they are ineffective for contraception. Emergency contraceptive pills are effective for sex before 72 hours, the shorter the time after sex, the better the effect of the pill, if more than 72 hours will not work. Contraceptive pills have two effects: one is to inhibit ovulation; the other is that if ovulation has taken place it can inhibit the implantation of a fertilized egg and play a role in contraception. Oral contraceptives are required to be effective within 72 hours of sex, if more than 72 hours of sex, there is no contraceptive effect. Fasting is required 2 hours before and after taking oral contraceptives, and if you eat food during oral contraceptives, it will increase the chances of nausea and vomiting. Sex should be strictly prohibited during menstruation. Hormone levels are lower during menstruation and ovulation usually does not occur, but sex during menstruation may result in endometriosis as well as symptoms of infections of the reproductive system, such as vaginitis, pelvic inflammatory disease, and other diseases.