Levonorgestrel
"I had the skyla put in after my period cramps had gotten just to much to handle. The birth control side of it was also a big reason as I have a long term relationship, so Skyla seems to be a great option for me. My older sister had Mirena put in just awhile before. And she said it hurt a great deal with insertion. So I was very nervous. I got it inserted and it felt like a 6 on pain; not even comparable to some of the cramps I had previously. I bled the next day with moderate cramping. Within two days the cramps were gone. The only thing bad about it is I spotted for about 2 cycles. Which isn't that bad because it's not a constent flow. It is only brownish dried blood that a pantyliner can easily handle.  No symptoms ever after that! 2 yrs!"