Reversible toxic psychosis.

Psychotropic medications may produce a toxic confusional state, especially in elderly patients. Tricylcic antidepressants particularly, and the phenothiazines to a lesser extent, may induce these behavioral changes by their anticholinergic activity. The situation may be compounded by the use of more than one psychotropic drug or the addition of an antihistamine or a belladonna alkaloid. Physostigmine can reverse the anticholinergic effects and clear the mental state.