Levonorgestrel
"Condom broke, got plan B over the counter no problem. Took it yesterday and so far I've had none of the symptoms whatsoever. So for all of you girls who are sitting there terrified reading this like I was.. Don't be afraid to take it. I've had NONE of the side effects. And its better to be safe than sorry. You'd rather take it and not need it than to look back in a month while you're staring at your positive pregnancy test and wish you had just taken the stupid thing. Hopefully it works :)"