Levonorgestrel belongs to the progestin class of drugs and is a strong progestin that has the effect of inhibiting ovulation. It can be used alone for emergency contraception after sex, and can also be used in combination with estrogen to form a combination tablet as a short-acting contraceptive. Levonorgestrel can also treat functional uterine bleeding, menstrual irregularities and endometriosis. Levonorgestrel is a very good emergency contraceptive pill, taken in time within seventy-two hours after the failure of no contraceptive measures or other contraceptive measures, the success rate of contraception is relatively high, levonorgestrel in taking attention before and after two hours do not eat, can only be taken once in a while, after using the drug to have sex again to take other contraceptive measures.