The main ingredient of the contraceptive pill Yutting is levonorgestrel, each tablet contains levonorgestrel about 0.75 mg for emergency contraception (contraception within 24 hours after intercourse), that is, unprotected sex or the use of other contraceptive methods failed to be taken within 1 day (the longest time is not recommended more than 3 days), the earlier the pill the better the effect. Levonorgestrel is a short-acting, rapid-acting contraceptive, the contraceptive mechanism is to inhibit female ovulation and fertilization of the egg implantation, and make the cervical mucus viscosity increases, sperm penetration resistance increases so as to effectively play the role of contraception. The most common adverse effects are endocrine disruption, resulting in dizziness, nausea, fatigue, menstrual cycle disorders, prolonged bleeding, etc., but there is also the possibility of contraceptive failure.