Abstract Background: Older patients are potentially at risk from the effects of polypharmacy (PP) and/or drug–drug interactions. Aims: To examine the effects of a targeted patient-specific prescriber feedback programme on patients prescribed more than 19 individual medications over the 3-month study period. Methods: The Commonwealth Department of Veterans’ Affairs commissioned a review of Repatriation Pharmaceutical Benefit Scheme claims data to identify patients potentially at risk of drug injury through either PP (≥20 unique medications during 3 months) or clinically significant drug interactions (DI). Dispensing information for the patient at risk, relevant clinical guidelines and a personalized covering letter were mailed to the main prescribing general practitioner of the identified veteran patient. The claims data were then re-analysed after the programme. Results: There was a significant reduction in the mean number of unique medications prescribed over a 3-month period 1 year after the prescriber feedback (mean change = −2.22; 95% confidence interval −3.54 to −0.90; P = 0.0013) for patients identified with ongoing PP. There was also a significant reduction in the number of DI pairs (mean change = −0.73; 95% confidence interval −0.77 to −0.69; P < 0.0001) for the patients identified with an ongoing DI. The number of patients dispensed one or more DI pairs decreased from 836 to 318 after the feedback. Conclusion: A targeted prescriber feedback programme can influence general practitioner prescribing at an individual patient level and, therefore, contribute to the quality use of medicines.