Emergency contraceptives are contraceptive methods used to prevent pregnancy during unprotected sex or for a period of time after contraception has failed, with medication being the most common of these methods. There are two common types of emergency contraceptive pills. One contains a high dose of progestin (usually levonorgestrel) in doses up to 5-10 times that of oral short-acting contraceptives. High doses of progestin can act quickly to inhibit ovulation and can thicken cervical mucus, preventing the passage of sperm. In addition, it can affect the lining of the uterus, preventing the fertilized egg from settling and preventing pregnancy through the combination of these effects. The principle of this type of drug is similar to that of short-acting contraceptives, but the effect is faster and stronger, while it is not suitable for long-term use due to more side effects at higher doses. Another type of emergency contraceptive pill works by antagonizing progesterone. This type of emergency contraceptive is usually composed of a small dose of mifepristone, which prevents the fertilized egg from settling in the uterine lining, thus preventing pregnancy from occurring. It is as effective as high-dose progestin as a remedy, but how it performs in the long term is not known and is therefore not a recommended method for routine contraception. There are two types of emergency contraceptive pills: hormonal and non-hormonal. Hormonal: ① estrogen and progestin combination: Yukstop (levonorgestrel 0.5mg + ethinylestradiol 0.05mg), 2 tablets for the first dose and 2 additional tablets after 12h. ② progestin-only preparation: norethindrone, half tablet for the first dose and half tablet after 12h. Non-hormonal: Mifepristone (single dose of 600mg can reach 100%, single dose of 25mg This effect is 74%-84%, also available 25-50mg in a single dose, the effect can reach 100%) The specific methods of taking emergency contraceptives are as follows Yutin: 4 tablets for the first time, then take 4 tablets 12h apart. After taking the pill may make the next menstruation early or postponed, the healing period of one month menstruation will not come, you should make a timely examination to exclude pregnancy. No. 53 tantric tablets: take one tablet immediately after sex, if there is no medicine at that time, you can take the medicine the next morning, the earlier you take the medicine, the better. Take one more tablet that night for three days, and one tablet every other day thereafter, four tablets in a row, for a total of eight tablets. Compounding with estrogen: 2 tablets of ethinyl estradiol (0.05 Mg each) plus 2 tablets of norethindrone (0.5 Mg each) to be taken after sex, and the same dose of the drug to be taken again 12 hours after taking the drug. Combination method of estrogen and progestin to reduce side effects such as nausea and vomiting caused by taking estrogen alone. Usage: Take 1 tablet (0.25Mg per tablet of levomethanon and 50Mg of ethinyl estradiol or 0.25Mg per tablet of levomethanon and 30Mg of ethinyl estradiol) within 72 hours after sexual intercourse. ”Mifepristone can also be used as an emergency contraceptive. The method of administration is to take one tablet (25Mg) twice a day after sexual intercourse for two days, for a total of 100Mg, and 0.4Mg (2 tablets) orally on the morning of the third day. The emergency contraceptive pill is effective within 72 hours after intercourse, but if you have sex during the pill, the time should be re-calculated. The earlier you take it, the better it is, but the failure rate is higher if you take it more than 72 hours.