abnormal uterine bleeding
"I wanted to love Mirena, but that was not the case and don't understand why doctors aren't honest about the side effects. I went on Mirena and was very happy since I never got a period, however Im very careful about my figure and knew that there were "rumors" (since my doctor said this was not true) relating  Mirena to weight gain. From the moment I had it inserted I watched what I ate and stuck to a 1300 calorie diet, working out 5 days a week... I still gained 10 pounds in the course of 3 months! I can't imagine what I would of gained had I not been watching what I ate and working out. I just had mine removed, hoping to go back to normal and cursing the day I decided to put that thing in my body!"