The pill has two functions: one is to inhibit ovulation; the other is to inhibit the fertilized egg from being laid if ovulation has already occurred, playing a contraceptive role. The oral contraceptive pill is effective within 72 hours of sexual intercourse, if it is more than 72 hours of sexual intercourse, there is no contraceptive effect. If you eat food during oral contraceptive pill, it will increase the chance of nausea and vomiting. If you have nausea and vomiting, the effect of the pill will be weakened, and if necessary, you need to take additional medication. After 1 week of taking the pill, there may be withdrawal bleeding, the amount of bleeding will be less than the amount of menstruation, and it will disappear after 1 week or so, which is normal and means that the contraceptive has a higher chance of success.