Levonorgestrel
"This product overall did it's purpose which is prevention of pregnancy. I did have bleeding about 6 days after I took the pill. Cramping that was not normal, and my 28 day cycle was off I ended up 4 days late. Those were the worst 4 days of my life by the way. But overall I'm not pregnant so I'm happy. But of course the best thing you can do I'd practice safe sex use condoms and birth control and let this be a last resort."