Deliriants, as their name implies, induce a state of delirium in the user, characterized by extreme confusion and an inability to control one's actions. They are called deliriants because their subjective effects are similar to the experiences of people with delirious fevers.
Included in this group are such plants as Atropa belladonna (deadly nightshade), Brugmansia species (Angel's Trumpet), Datura stramonium (Jimson weed), Hyoscyamus niger (henbane), Mandragora officinarum (mandrake), and Myristica fragrans (nutmeg), as well as a number of pharmaceutical drugs, when taken in very high doses, such as diphenhydramine (Benadryl) and its close relative dimenhydrinate (Dramamine). Uncured tobacco is also a deliriant due to its intoxicatingly high levels of nicotine.
In addition to the dangers of being far more disconnected from reality than with other drugs and retaining a truly fragmented dissociation from regular consciousness without being immobilized, the anticholinergics are toxic, carry the risk of death by overdose, and also include a number of uncomfortable side effects. These side effects usually include dehydration and mydriasis (dilation of the pupils).
Most modern-day psychonauts who use deliriants report similar or identical hallucinations and challenges. For example, diphenhydramine, as well as dimenhydrinate, when taken in a high enough dosage, often are reported to evoke vivid, dark, and entity-like hallucinations, peripheral disturbances, feelings of being alone but simultaneously of being watched, and hallucinations of real things ceasing to exist. Deliriants also may cause confusion or even rage, and thus have been used by ancient peoples as a stimulant before going into battle.
Read more about this topic: Psychedelics, Dissociatives And Deliriants