Levonorgestrel
"I got Mirena put in about two months ago. Insertion sort of hurt, not terribly, but it did hurt.  But, it only takes a few minutes so it wasn't a big deal. The first two or three weeks were very "crampy" for me. They say this happens more with women who have not ever had children (that's me).  But, the crampy feeling went away.  Now, I don't feel a thing and it's all good.  I've only had it in a short time and have had two periods extremely light, like I need about four-five tampons for the whole period and even a liner would probably be sufficient. I have lost a couple of pounds since having the Mirena, not sure if there is a correlation or not.  The only downside is I have noticed an increase in pimples."