Drugs that induce delirium.

Drug-induced delirium is often seen in clinical practice. Most knowledge about delirium-inducing drugs comes from reports on side effects, and few systematic studies have been done in the field. Delirium is strongly associated with anticholinergic activity; drugs of different classes, including tricyclic antidepressants and traditional high-dose neuroleptics, constitute a high-risk group. A large number of drugs, including benzodiazepines, sedatives, dopamine-activating drugs, antiepileptics, histamine H2 receptor blockers, digitalis and analgesics, are less frequently associated with delirious reactions and constitute a medium-high-risk group. Some of these drugs do not have anticholinergic effects but in vitro have shown to bind to muscarine receptors. The risk of inducing delirium in frail elderly and demented persons clearly suggests that drugs which might induced delirium should be avoided.