This is a class of drugs that can provide meaningful, safe experiences if used in the correct circumstances armed with the correct knowledge. These drugs are dangerous and have been proven to cause brain damage (see: Olney's lesions) so regular use is definately not advised. Intense experiences will follow use of these substances, experiences that aren't as colorful, shiny, and happy as other psychedelics such as LSD and magic mushrooms, and bad trips are a possibility. As with all mind altering drugs, the rules of set and setting still apply. And no driving! That said, here's the info:

DXM:

Ketamine:

Nitrous Oxide:

PCP: