Emergency Contraceptive Pill - One Tablet - Reduces Chance of Pregnancy After Unprotected Sex - emergency contraceptive can help prevent pregnancy when taken within 72 hours (3 days) of unprotected sex (Works even better if used within 24 hours). The sooner you take it, the better it works. Not be used as regular birth control. Use as directed. Convenient and effective! Comparable to Plan B One-step Emergency Contraceptive and My Choice Emergency Contraceptive Tablet.