Polypharmacy is usually defined as the use of five or more drugs, including prescription, over-the-counter, and complementary and alternative medicines5,6 The more medicines a patient takes, the harder it may be to obtain an accurate medication history, which impedes informed medication review and prescribing (refer to Part A. Medication management). The incidence of adverse drug reactions increases with the number of medicines used.7 Polypharmacy may be a barrier to adherence because of the associated complex medication regimens, increased risk of adverse drug events and high medication costs.
Polypharmacy is associated with suboptimal prescribing. The more medicines a patient is exposed to, the more likely they are to be prescribed inappropriately and the poorer the patient's overall function. In addition, the more medications a person takes, the more likely they are not prescribed one or more indicated medicines.8
The ‘prescribing cascade’ – where one medicine is begun to treat the adverse effects of another – can also contribute to the number of medicines taken.5,9,10
Risks from multiple medicines include adverse effects, hospitalisations, functional impairment, geriatric syndromes (eg confusion, falls, incontinence, frailty) and mortality.11
Appropriate prescribing comprises the use of medicines associated with strong evidence of benefit when indicated, monitoring and dose adjustments while using, and ceasing those with questionable or no evidence of efficacy. There are many tools used to reduce polypharmacy and inappropriate prescribing.