There is another thread here that discusses this, I think it's in the BCP forum, I'll try to find it and post it. I'm sorry but I don't think you can trust your doctor on this one. The Mirena IUD contains on of *the most* androgenic progesterone hormones found in birth control. I know many of our most heartbreaking symptoms including excess hair, hair loss and others are caused by androgens. I would encourage anyone with PCOS who is considering any type of hormones to do extensive research to try to minimize any bad effects that may come from them. Most doctors have our best interests at heart, but we sometimes trust them to know everything and they just can't. Medical care should be a partnership between the patient and the doctor, you know what I mean?
*Steps off soapbox*
