The 24-hour emergency contraceptive pill is not accurate. Emergency contraceptive pills are emergency contraceptive pills used within a few hours or days after unprotected sex or contraceptive failure, and the common ones are mifepristone, compound levonorgestrel tablets, and levonorgestrel tablets. 1. Mifepristone tablets: belong to the anti-progestin preparations, with anti-progestin and anti-glucocorticoid effect, within 72 hours of unprotected sex, take mifepristone 10 mg can be, need to fast for 1-2 hours after taking the drug. 2. Compound levonorgestrel tablets: containing ethinylestradiol and levonorgestrel, containing ethinylestradiol 30ug, levonorgestrel 150ug, belonging to the estrogen-progestin compound preparation, hormone content is low, in the unprotected sex, within 72 hours of taking four tablets, 12 hours and then take four tablets. 3. levonorgestrel tablets: belonging to the monoprogestin preparation, with a higher dose, one tablet is taken within 72 hours of unprotected sex, and one tablet is repeated in 12 hours. These drugs can produce contraceptive effect in unprotected sex or a few hours or days after the failure of contraception, but some people will have nausea, vomiting, irregular vaginal bleeding and menstrual disorders after taking the drug, if the menstrual period is delayed for more than a week need to be promptly excluded from pregnancy.