If you go and have it done at your GP, they freeze it with liquid nitrogen. Doesn't really hurt, just stings a bit and once they take it off, it stops stinging. They usually give it two goes. Usually they turn black in a couple of days and drop off, or at least shrink. However, they will go on their own eventually (I had a small one on the inside of my thumb for about two years and it cleared itself up in the end. It was only small though, so didn't really bother me). Oh, and if you get it done by your local GP, it's completely free.