Levonorgestrel
"I had the biggest pregnancy scare of my life. I had sex with someone I had just met, about 2 weeks ago (the day before I was due to start my period, so I didn't think anything was wrong). The didn't ejaculate in me, but I had read enough forums of "pre-cum pregnancies" to be afraid. I took Next Choice One Dose the following day (about 48 hours after sex), and no side effects until 3 days after taking it, which, then I had nausea, no vomiting. In these last two weeks, I was getting freaked out because my period didn't come. Woke up this morning, though, and it's here! Don't be afraid, don't google anything. Just take this and remain calm. You'll be okay!"