Half an hour after intercourse, correctly taking the pill is usually able to achieve the contraceptive effect, but can not be completely guaranteed, it is recommended to judge according to their own actual situation. Women who take emergency contraceptive pills within 72h after unprotected intercourse can usually achieve contraceptive effect, the main component of the drug is levonorgestrel, which affects the normal secretion function of the ovaries, so as to achieve contraceptive effect. However, it is worth noting that the contraceptive pill contains a large hormone content, relatively large impact on the body, and in serious cases can cause endocrine disruption, amenorrhea, it is recommended that under the guidance of a doctor to use reasonably. It is recommended that women who do not have the need to prepare for pregnancy should take good contraceptive measures to avoid taking drugs to have a greater impact on the body.