"i had sex without a condom and i was not taking birth control regularly. he came inside of me and i was really worried. i took plan b within the next 12 hours after having sex. i was 5 days late on my period and then it came. the cramping is really bad but it&#039;s worth it. if you&#039;re worried about it not working or it&#039;s past your period, it does mess up your cycle so give it at least a week after your period to come! good luck!"