abnormal uterine bleeding
"I have had the Mirena for 13 months now.  I had light bleeding in between periods the first two months and then just a light brown discharge between what should have been periods ever since.  I had cramps the first 8 months, but they were sporadic and disappeared within 30 seconds each time I felt one.  I would get occasional cramps when I should have had a period.  No skin breaking out, no mood swings at all.  I want to KISS the person who invented this.  And it didn't hurt when I had it inserted.  Felt like a huge menstrual cramp for about 30 seconds and that was it and I have never had a baby.  So far, so good!"