Anticholinergic syndrome occurs following overdose with drugs that have anticholinergic activity.

Examples of these are tricyclic antidepressants, antihistamines and atropine. Features include flushed skin, urinary retention, tachycardia, mydriasis (dilated pupils) and agitation.

Physostigmine, a reversible inhibitor of acteylcholinesterase, is effective in treating anticholinergic symptoms but there is a significant risk of cardiac toxicity (bradycardia, AV conduction defects and asystole) with the drug.