Emergency contraceptive pills consist of high doses of progestin or anti-progestin ingredients. Taking emergency contraceptive pills once will have an effect on the hormone levels in the body, which is usually not too great. Emergency contraceptive pills are not used as a regular form of contraception and should not be used frequently to avoid serious effects on the body. Emergency contraceptive pills include levonorgestrel, mifepristone and other drugs, in which the hormone content is relatively large, so as to achieve the effect of contraception in a short period of time, usually taken within 72 hours after unprotected sex, after taking the pill will cause hormonal fluctuations in the body, and may appear dizziness, nausea, vomiting, drowsiness and other adverse reactions. Emergency contraceptive pills can not be used for people with thrombophilia and severe liver and kidney dysfunction. If you need to use emergency contraceptive pills, it is recommended to do so under the guidance of a doctor, and if there is no need to prepare for pregnancy, you need to take adequate measures to prepare for pregnancy when having sex.