As the most prominent consumers of prescription medications, elderly patients stand to benefit the most and are also at greatest risk of toxicity from our increasingly complex, effective, and costly pharmacopoeia. When pharmacotherapy is indicated, choosing the right drug in the right dose for an elderly patient represents one of the most difficult challenges in all of medicine, but also can yield the most gratifying outcomes. Likewise, few interventions in geriatric practice are as elegant in process, and as “heroic” in outcome, as identifying and treating adverse drug effects. Thorough knowledge of some of the principles outlined here will enable the clinician to wield this powerful double-edged sword with the least possible risk and with the maximum benefit for patients.