I know someone that has tried many if not all of these drugs: ayahuasca, mescaline, ketamine, iboga, DMT, and much more! At one point he started to have hallucinations even when he was "clean". He claimed to constantly seeing some little beings, alien-like creatures who were harassing him!
Soon he developed paranoia, anxiety, depression, and he said he could not get rid of those hallucinations and voices in his head! He was very bad! He finally recovers from it, and after that experience, he and some of his friends were going around in the country to high schools to teach young folks about his experience with these substances and to warn them about the not-so-pleasant side of them!
Mind-altering substances can be a very dangerous practice! Graham Hancock, in his book "Supernatural", mentions that all the mind-altering substances including different practices such as rhythmic dances, rock, EMF, hypnosis, or shamanism are being used to enter in contact with the so-called "aliens", which are the same with spirits or demons (the fallen angels from the Bible) or the Jiins from Islam and so on.
They are real entities and can enter in contact with people during an altered state of mind.
Communication with spirits is a very old practice! It is daily practiced in different cultures in South America, Asia, Africa, and even in the western world under diverse forms: voodoo, Umbanda, Candomble, Wicca, shamanism, magic, bioenergy, dowsing, Seance, tarot, astrology, Ouija Board, occultism, meditation, necromancy, channeling, spiritism, etc.