It's ironic that some of the most effective treatments for addiction are also illegal, Ibogaine has proven to be very effective treating heroin and meth addictions, ayhauasca as well as well as being effective treating depression, thankfully the door is open to proper research on these powerful medicines again after being shut down for so long.
LSD was very nearly a part of the AA 12 step program before being made illegal and has had positive results in treating addictions along with psilocybin.
If you're at all interested in the subject MAPS and reset me are two good sites to start off, with lots of great information.
http://reset.me/story/howpsychedelicssavedmylife/
http://www.maps.org/
I have a bit of personal experience myself, i was pretty much an alcoholic for most of my adult life before stumbling upon psychedelics, don't get me wrong i was using them for partying but had a profound effect on me, probably one of the most significant events in my life, i'm a far better person for having found them, they've been powerful medicines for 1000's of years and we are only just now beginning to acknowledge that.