Emergency contraceptive pills are commonly levonorgestrel correct use of its contraceptive effectiveness rate of about 95%, need to pay attention to exclude contraindications before the use of the drug, after the use of the drug is recommended to check whether the pregnancy. Levonorgestrel and other emergency contraceptives can be used for emergency contraception after unprotected sex, need to take the drug within 72 hours after sex. In general, the earlier the emergency contraceptive pill is taken, the more effective the contraceptive effect is, and the drug is about 95% effective. If you do not have your period for more than 7 days after using the emergency contraceptive pill, it is recommended to go to the hospital to test for pregnancy. After taking the pill, if there is more than vaginal bleeding, nausea, vomiting, headache, dizziness and other symptoms, it is recommended to go to the hospital in time. It should be noted that the pill is prohibited for those who suspect or have pregnancy, as well as for those who have breast cancer, tumors of the reproductive system, hepatic impairment, cardiovascular disease, diabetes, mental depression and other diseases, and for those over 40 years of age. Taking emergency contraceptive pills needs to be under the guidance of a clinician.