Levonorgestrel
"I'm a 21 year old who has never given birth and had skyla inserted yesterday. Honestly if I had it my way I would've stuck to the pill! But as I've recently been  put on medication that severely decreases the effects of hormonal birth control, IUD it is! 
I took the 800mg of Advil (and a klonopin) an hour before. This definitely was not a fun experience for me. And I don't say this to scare anyone, the pain is definitely uncomfortable, but my body went into shock after all the anxiety and I wound up almost passing out and throwing up. My doctor handled it great though, did an ultrasound to make sure my discomfort wasn't due to anything messed up. Some people have strong reactions some don't. Just know your body, 24 hrs later and I'm all good!"