Mirena
"This is for the insertion only. 
Don't listen to the reviewers that say the insertion is excruciating. I read all the horror stories on the internet and waited to get the mirena for 2 years because of them. 
I finally got it today and the pain wasn't as severe as I thought. It was some weird, intense cramps and uncomfortable pressure and stopped as soon as the doctor was finished and I've experienced NOTHING since. The sensation lasted for maybe 3 minutes total, I couldn't believe how quick the procedure was. Worrying about the pain was the worst part. I was able to sit up right away (no dizziness or nausea) and drive myself around running errands. I've had some minor spotting since but that's about it. 
I'm 28 with no kids. I took 3 advil."