This is not a "new" side effect but I have to let everyone know about the acne!!! I've always had horrific cramps, heavy bleeding, and periods that lasted 8 days. So, Mirena turned out to be great for all of that! I hardly even know when my period is coming, it's barely even there.
HOWEVER.....the acne is so bad i can't stand it! it never lets up! and they leave scars. as soon as one huge pimple is gone, another takes it's place. I'm beginning to think about having it removed. This is the worst acne I've ever had. Consider this before you get one...