Levonorgestrel
"I have taken plan b twice in my life. The first time I took it, it was just two or three days after my period had ended and then five days later I started my period again. I was a little concerned at first thinking there's no way it could have made me start that early. Two periods within three weeks is crazy. So then the month went on and I started worrying if that really was my period, but in the end it just reset my cycle. The most recent time, I had sex on day 10 of my cycle and took the pill about 11 hours later. 6 days have passed since then and I'm having some bleeding and bad cramping. It's not normal period bleeding for me but it's more than just spotting. I'm waiting now to see if this is my period or just bleeding side effects."