Levonorgestrel
"My experience was absolutely horrible. Birth control works different for everyone but this was by far the worst pain I've ever been in. Immediately after inserted I was in excruciating pain. I started having heat waves and extreme cramping. This lasted for weeks. I had an ultrasound done to see if it was causing any ovarian cysts, or if the iud wasn't inserted correctly and my ultrasounds came back normal. A week later I had to have it removed (after a month) because of how much pain I was in. I would highly recommend not having this at all, because of how severe my pain was. I had to take pain killers every 2 to 3 hours, and I would wake up in the middle of the night because of how much pain I was in. Absolutely terrible!"