DELIRIUM - An abnormal mental condition based upon hallucinations or delusions. Some medications may cause delirium. Examples include: amantadine, aminophylline, anticholinergics, tricyclic antidepressants, cimetidine, digoxin, glucocorticoids, isoniazid, levodopa, methyldopa, penicillins, phenothiazines, and sedatives. Severe alcohol withdrawal can cause a form of delirium known as delirium tremens. Features include confusion, agitation, and tactile hallucinations (feeling things crawling on you).