Levonorgestrel
"So after reading all the reviews on here which totally saved me from having a panic attack I had to write about my experience. I'm 20 years old and me and my bf had unprotected sex on August 29th, he pulled out but I was still super paranoid so I took Plan B 11 hours later. I had absolutely no side effects so after about a week I was convinced that the pill didn't work for me and even started thinking about how I was going to tell my parents, my friends, the whole thing! So crazy I know.. So anyways I got my period today and am so happy. Trust me even if you don't experience any side effects does not mean the pill isn't working! I promise, Just try not to freak out and keep yourself busy. Also my period came a little less then a week early"