I and six of my friends all have had the Mirena IUD. It seemed great at first - no pills, no periods, no problem! Or so it seemed...
All but one of us (myself included) had it removed early for unfavorable side effects, which included depression, mood swings, irritability, anxiety, loss of sex drive, weight gain (and the inability to lose), oily skin and bad acne. We all had different degrees of side effects: one only had weight gain, but I had them all, and everyone else fit in somewhere in between. While I had no periods or cramping, one of my friends had extremely heavy, painful, irregular periods.
When I was first experiencing symptoms, I attributed them to pregnancy hormones that hadn't yet left my body, but after a year I knew that couldn't be it. I was thinking I was going crazy, and thought I needed to go on some kind of medication to control my moods. It was like I was a completely different person. No amount of diet and exercise could shed the 15lbs I'd gained in the year AFTER giving birth. I had worse acne than when I was a teenager. My husband thought it was the Mirena and I didn't believe him, because I had read all of the literature on it beforehand and none of what I was experiencing was mentioned. And I had been on the pill for over 10 years before we tried for a baby, and had no problems with those hormones whatsoever. So he did research and found two forums dedicated to Mirena, with thousands of women complaining about the side effects.
So I had it removed after having it just over a year, and I am not kidding you, that very evening it was almost like a cloud had been lifted - all of my senses seemed clearer and I felt calm, and within a week I actually WANTED to have sex. I felt myself again! And finally I was able to lose the weight. I'm not back down to where I was before I was pregnant, but I'm back to where I was before I had the Mirena put in.
My one friend who still has it in claims she loves it and is not experiencing any problems, but yet has recently had to go on Paxil for anxiety and irritability, when she had never had a problem before. Coincidence? I think not. I want to tell her I think it's the Mirena, but she's convinced it's great.
My husband and I believe that since the makers of Mirena suggest that it's best for "women who have had at least one child," they're hoping women will choose it as the first means of birth control after having a baby, and therefore any side effects experienced (which for me, seemed like pregnancy times ten), will be attributed to, or blamed on, lingering pregnancy hormones.
I am happy for those who have it and think it's great, and I don't want to convince them otherwise, but I would definitely never recommend getting it. If you have it and you're feeling things you wouldn't normally, then I am positive that is the culprit.