I think this is the first time I've ever posted. Obviously, I feel it's important to put my 2 cents in! As said many times previously, you're going to get multiple different answers. I'm so glad to hear that many women have had success with the Mirena. The concept is good but just didn't work out for me. I had my inserted when my 3rd son was about 3 months old and had it removed a little over a year later. My symptoms are very similar to those expressed by the other women, as well. But I'll add in one "con" that no one else has mentioned:
Pros: "Mindless" non-permanent birth control (no pill to remember, etc.) which is important with 3 little children; spontaneous sex life without constant thoughts of "did I take my pill ontime?"; easy insertion and removal
Cons: small amt of cramping with insertion but spotted for about a month; fatigue & extreme moodiness (I was yelling at my children all the time); decreased sex drive; headaches (I've never been prone to having them); inability to lose weight despite a great diet and breastfeeding, but that could be a part of having a third baby & my increasing age; a little bit of acne but not as bad as reported by others; CONSTANT discharge of some sort - my periods returned at around 7-9 months but were never consistent - periods were light but when I wasn't bleeding I had a whitish discharge that was driving me crazy (later explained by the OB/GYN who removed it that it's the body's way of trying to fight the foreign body that's present in your uterus); LASTLY, I had 2 ovarian cysts that burst. First time happened about 6 months after it was inserted and then about 11 months after inserted. I thought I was having an appendicitis. So painful I was doubled over on the floor, couldn't speak or breath from the pain and luckily my 3 children were safely playing while I contacted a neighbor to come over (my husband was deployed the first time it happened). I was told by the OB who removed it that ruptured ovarian cysts are quite common in his experience.
I had it removed in Dec and have felt much better ever since. I've started taking the pill again which doesn't give me all the side effects. It was hard to put into words how I felt when I had it in but I just didn't feel like myself. I kept telling myself it was because I was getting older, had 3 small children, my husband was away a lot and I was doing it all myself, etc. But I just kept thinking, I think it's the Mirena. I hope all the info you're getting from these posts are helping, rather than hindering your decision. Good Luck!