The emergency contraceptive pill is not effective after eating, the emergency contraceptive pill can only work for 72 hours after intercourse, if you take the pill again after intercourse is not effective, this drug is highly effective progestin, inhibit ovulation disrupt the normal endocrine state, and make the endometrium become very thin, not conducive to fertilization of the egg, if there is sexual life to eat the earlier the effect is better. And this drug contraceptive effect can only reach 85%-90%, but also about 10% of people will be normal pregnancy after taking the drug, if you take the drug and then have sex, the pregnancy rate is very high, because this drug has no effect.