Levonorgestrel
"I've had Kyleena for about 10 days, and I can't say enough good things! My insertion experience was much less painful than I expected (I'm 30 y/o, no kids). I took 550 mg of naproxen an hour before insertion, and I only had two sharp cramps, both of which only lasted a few seconds. I had some moderate cramping that evening, and otherwise it's been great! I'm expecting my first period with it in the next day or so, and I'm having more cramping than usual, but I understand that's pretty normal for your first period with an IUD. Don't let nerves dissuade you from getting one!"