Levonorgestrel
"I took this about one hour after unprotected sex, he pulled out and when he finished he didn't finish inside of me but some of his semen did land on my area, and of course I started freaking out. So I went to the nearest Walmart and bought this Plan B pill. This happened on July 17th, and my period was due for around July 28th-30th somewhere around those days. I didn't experience many side effects, just some cramping in my abdomen and a little above my hips & this went on for about 2 weeks on and off. I was very worried but I was trying not to stress too much because stress does affect your period, but I'm glad to say that I got my period on July 30th and it was like my usual monthly period :)"