Drugs/alcohol and enlightenment?

To say they just cause hallucinations, as some people are claiming, is an understatement. They cause a complete change in perception that extends well beyond sensory hallucinations, and the way these things are made manifest through chemical changes in the brain are not well understood, although some research suggests that it is similar to religious experiences. I think that while a certain drug may present a piece of truth, it's important to find this truth without taking these sorts of chemicals, as it makes it even harder to discern what's real and what's not spiritually speaking. Although a certain experience I had quite some time ago was very helpful to me, there have been setbacks when it came to hallucinogens as well; that's why I believe it's best to stay away from them and strip away the ego slowly, without forcing immediate change. So to finally answer your question, yes, they can create spiritual experiences, and anyone who's been there can tell you they definitely create OBEs, at least subjectively.