Polypharmacy in older adults: why the number of medications itself becomes a risk factor

Polypharmacy, commonly defined as taking five or more medications concurrently, is increasingly common in older adults managing multiple chronic conditions, and research has found that the risk of adverse drug interactions doesn't increase linearly with each additional medication — it compounds, since more medications create exponentially more possible interaction pairs to consider.

A specific and well-documented risk is the prescribing cascade — where a side effect from one medication is misidentified as a new medical condition and treated with an additional prescription, rather than recognized as a drug effect and addressed by adjusting the original medication. This pattern has been identified as a meaningful contributor to unnecessary polypharmacy in geriatric care research.

Periodic medication reconciliation — a structured review, ideally by a pharmacist or physician with geriatric expertise, checking whether each medication is still necessary, whether doses need adjustment, and whether any combination poses interaction risk — is the intervention with the clearest evidence for reducing polypharmacy-related harm. This is worth requesting explicitly at care transitions (hospital discharge, new specialist involvement) when medication lists are most likely to have accumulated redundancy.