I've always considered myself lucky that alcohol doesn't improve my stuttering. I did abuse energy drinks early on in my career as it seemed to help me power through words. I knew for this reason I would never try coke/speed/etc. I'm sure I'd get hooked. Also, I smoked a lot of weed growing up. It wasn't directly related to the stutter but was part of just distracting myself from life. I'm glad to have dropped that habit now.