Levonorgestrel tablets are emergency contraceptives and should be taken within 72 hours of intercourse. The earlier they are taken, the more effective they are in preventing pregnancy. The earlier the pill is taken, the more effective it is in preventing pregnancy. Women should remain fasting for two hours before and after taking the pill to facilitate the efficacy of the pill. Levonorgestrel is used as emergency contraception for women in case of accidental failure of other contraceptive methods or unprotected use. Levonorgestrel tablets contain a large amount of progestin, which has the effect of inhibiting ovulation. It can change the endometrial trait causing the development of the fertilized egg and the endometrium to be out of sync, and it can change the normal speed of the fertilized egg in the fallopian tube, preventing the pregnant egg from being laid. In addition, it can increase the viscosity of the cervical mucus, which is not conducive to sperm penetration. In addition, the emergency contraceptive pill is used to prevent unwanted pregnancies and is only indicated for one unprotected sexual intercourse and therefore cannot be used as a commonly used method of contraception.