I just wanted to share my experience with Mirena and hope that it helps someone else. I had Mirena inserted on 7th July 2008 after having a copper IUD removed. I chose the Mirena because I had heavy periods and understood that the hormone would be localized to my uterus and only a very small amount would enter my bloodstream.
After a very short time (probably a day or so), I started getting symptoms of nausea, headaches, dizziness, forgetfulness, depression, bloating, cramping and just a general feeling of something wrong with my body. One day I was just sitting at my desk at work and my heart starting racing! I also felt very anxious and panicky a lot of the time.
The nausea and headaches just got worse every day until I couldn't stand it any longer - I was completely miserable - and called my doctor's office to make an appointment to have the Mirena removed. When I went to the appointment, my blood pressure was sky high and I had a severe headache. Although my doctor said she believed I was having these symptoms, she didn't think the Mirena could be the cause.
Anyway, I had the Mirena removed on July 25th and a few hours later, my headache had completely gone. I slept great that night and woke up for the first time in 2 weeks not feeling nauseous. I had my blood pressure checked today (2 days later) and it was back to normal.
I'm pretty sure that the Mirena made me sick and I wish I'd done some research before I had it inserted. It's been interesting to learn that so many people are experiencing similar problems.