abnormal uterine bleeding
"I've had Mirena in for 4 1/2 months now and I'm still bleeding. I'm going through about 2-3 tampons every 24 hours. I've gone through about 6-7 snaps where it'll stop for a day or two and then it starts right back up. I'm out of town for a few months, but as soon as I get back I'm having it taken out. I haven't gotten pregnant during those snaps, so I guess it's effective if you're willing to spend your life bleeding."