Acetylcholine-like hallucinogens are much less commonly used recreationally, because their effects are generally extremely unpleasant. Acetylcholine is a neurtransmitter that helps your muscles take action, among other things. These hallucinogens cause an overdose of norepinephrine and adrenaline, leading to panic, high blood pressure, and stroke. This group, which includes atropine and scopolamine from nightshades and mandrakes, can be deadly in high doses, but have been used historically to treat problems like diarrhea. I wrote about these hallucinogens in my post Hallucinogens of Europe.
Glutamate-like hallucinogens (like PCP and ketamine) were originally put to use as anesthetics. Since they render glutamate, an amino acid used for learning, unable to function normally, they can cause blackouts and memory loss.
Having an increased understanding of how each psychedelic works in your body can help you better choose which ones are right for you. We should all have the right to choose, but please choose wisely.