A drug with psychotomimetic actions mimics the symptoms of psychosis, including delusions and/or delirium, as opposed to just hallucinations. Some drugs of the opioid class have psychotomimetic effects, such as pentazocine and butorphanol.[1]
Carl Sagan also used the word psychotomimetic in his anonymous article "Mr.X" to describe the effects of the herb marijuana. There is evidence that cannabinoids, the active substance in marijuana, are psychotomimetic,[2], especially delta-9-tetrahydrocannabinol (THC). D'Souza et al. (2004) found that intravenous THC produced effects that resemble schizophrenia in both the positive symptoms (illusions, paranoia and disorganized thinking) and negative symptoms ("...apathy, anhedonia, alogia, asociality, avolition).[3] Some types of marijuana may be more psychotomimetic than others, possibly due to the action of cannabidiol (CBD), which inhibits P450 3A11's metabolic conversion of THC to 11-hydroxy-THC, which is four times more psychoactive.[4]p. 39
Psychotomimetic drugs (also referred to as psychomimetic drugs) affect thought, perception, and mood, without causing marked psychomotor stimulation or depression. Thoughts and understanding of the surroundings and self tend to become dreamlike and confabulating rather than being sharpened or lucid, and the changes are more disturbing than a mere shift toward depression or euphoria. The main difference between psychotomimetics and other drugs is considered to be that the peripheral action of psychotomimetics cause sweating, tachycardia, hyperthermia, sleepiness, and euphoria/dysphoria to occur indirectly and can vary immensely among users, rather than directly by the action of the drug, as is the case with dopaminergic and serotonergic drugs like heroin and MDMA, respectively. Drugs that purely cause psychotic symptoms, or have the severe potential to cause psychotic symptoms in post sobriety, include deliriants such as scopolamine, atropine, hyoscyamine, diphenhydramine, dimenhydrinate, etc., as well as prolonged stimulant use, prolonged use of marijuana, certain opiates, and dissociative drugs like dextromethorphan and phencyclidine.
Contrary to popular thought, psychedelic drugs such as LSD and magic mushrooms are not considered to be psychotomimetic. Their action is not believed (anymore) to resemble any psychotic state of mind as with other drugs. However, they do have similar effects, but psychosis has no resemblance to the lucidity and clarity that exists within the experiences of psychedelic hallucinogens, which are not hallucinogenic in the sense that they create a sensory experience from nothing, but rather hallucinogenic in the sense that they cause pseudohallucinations (i.e., distortions in the way the user perceives the world rather than false constructions in the world around the user).