These drugs are not usually regarded as psychedelic, although they have a great deal in common historically, culturally, and pharmacologically with other drugs taken for their mind-altering powers. They are called anticholinergic because they block the action of acetylcholine, a nerve transmitter substance that controls the contraction of skeletal muscles and also plays an important role in the chemistry of the brain. They are called deliriants because their effects at high doses include incoherent speech, disorientation, delusions, and hallucinations, often followed by depression and amnesia for the period of intoxication. The classical anticholinergic deliriants are the belladonna alkaloids:

These tropane derivatives, the most powerful and important of which is scopolamine, are found in differing concentrations in various plants of the Nightshade Family or Solanaceae, among them deadly nightshade (Atropa belladona), mandrake (Mandragora officinarum), black henbane (Hyoscyamus niger), jimsonweed (Datura stramonium, and over twenty other species of henbane and datura. Of all psychoactive drugs , only alcohol has been in use for so long over such a large part of the world. For thousands of years on all inhabited continents the belladonna alkaloids have been a tool of shamans and sorcerers, who take advantage of the sensations they evoke to leave their bodies, soar through the air, or change into an animal in their imagination. They also produce toxic organic symptoms like headache, dry throat, loss of motor control, blurred vision, and greatly increased heart rate and and body temperature; death from paralysis and respiratory may occur.

The belladonna alkaloids are so terrifying and incapacitating - the physical effects often so unpleasant, and the loss of contact with ordinary reality so complete - that they are used only with great caution and rarely for pleasure. For the same reasons, ironically, they are not regarded as a drug abuse problem and can be bought in small doses on perscription or in over-the-counter sedatives and pills for asthma, colds, and motion sickness.