UBC Faculty Research and Publications

How well do you know your anticholinergic (antimuscarinic) drugs)? University of British Columbia. Therapeutics Initiative


Therapeutics Letter 113 is intended to remind clinicians of commonly used drugs that have anticholinergic (AC), or technically, antimuscarinic properties, and of their potential adverse effects.Prescribing Principles: Before prescribing, consider a patient’s total anticholinergic burden by reviewing all drugs. Inform patients about anticholinergic effects of over the counter drugs (e.g. “Gravol” or “sleep aids” containing diphenhydramine). Alert patients and families that using drugs that block cholinergic neurotransmission in the brain can increase the risk of cognitive impairment and may be risky long-term. Prescribe anticholinergics only for a clear indication. Document the purpose in the clinical record and on prescription directions (“indication-based prescribing”). This should appear on the medication container label and will facilitate periodic review and deprescribing. Use low doses for the shortest possible time; reassess often for predictable adverse effects (Table 3). Ask about subtle manifestations of anticholinergic toxicity such as impaired cognition, impaired visual accommodation, slurred speech from a dry tongue and mouth, reflux from delayed stomach emptying, or frequent urination due to incomplete voiding. If you suspect dry mouth, see whether a swish of water improves speech. If unsure whether antimuscarinic effects may be in play, consult online resources, including drug monographs.

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