If you have sex within 24 hours after taking the emergency contraceptive pill, the pill is generally not effective in preventing pregnancy, so you need to take an additional emergency contraceptive pill to avoid an unplanned pregnancy. The contraceptive effect of levonorgestrel is relatively obvious. The earlier you take it, the better the effect. Statistical data shows that the contraceptive success rate of this type of emergency contraceptive pill can reach 98%, but not 100%. In addition, there are contraindications to taking levonorgestrel, such as breastfeeding within 6 months after delivery, the presence of cardiovascular disease risk factors, hypertension and vascular disease, the need for major surgery, coagulation-related mutations, significantly impaired liver function, etc.