Levonorgestrel
"Absolutely horrible. Took ibuprofen prior to insertion. When I got up and went to leave I passed out but insertion was little more than a pinch(no previous pregnancies). 

While on it I had continuous heavy bleeding, constant pain and hot flashes. I could not even go to work or do pretty much anything but lay down with a heating pad- and I'm used to severe pain. After being told by my doctor repeatedly to give myself time to adjust I finally had it removed after 3 months. It then took 2-3 weeks for the pain and bleeding to stop and hot flashes took about 2 months to go away."