###Human: What is the success rate for taking Unwanted 72 within half an hour of unprotected sex? ###Assistant: Hello. The average success rate of an emergency contraceptive pill may range from 75 to 85 % after an unprotected intercourse if taken immediately. So, rest assured and wait till the expected period. But, however, I would suggest to use this pill only as an emergency back up, and go for a consistent contraceptive method like oral contraceptive pills which are more effective and cause fewer side effects. Because this emergency pill is high dose hormonal pill, side effects like delay in periods or irregular bleeding may occur.