In high school, prior to my traditional Catholic conversion, a buddy and myself did some red microdot LSD on Friday 13th. Bad idea. My buddy started hearing voices and I said, "David are you hearing voices,?" to which he replied, "Yes, I am hearing voices that say, 'kill, kill, kill'." I heard the same voices. Luckily, I pulled out my St. Joseph Edition Bible and started reading it out loud, and the voices left. We also saw angels outside flying through the air. I am convinced that hallucigenic agents will very often open the door to the demonic.
I knew one guy, his uncle did one hit of Grateful Dead LSD, and he thought spiders were all over his body. He tried to get the spiders off with a steak knife. The guy ended up stabbing himself to death.