Polypharmacy-related issues include adverse drug effects, drug-drug interactions, drug-disease interactions, reduced health-related quality of life, disability and hospitalizations, decreased treatment efficacy and lower overall survival for some cancers, and reduced medication compliance.

Using multiple medications with anticholinergic effects results in an ‘anticholinergic burden’, potentiating the effect of the individual medications. Adverse drug effects may occur decades after ceasing use of anticholinergic.