As the population ages, more people will have comorbid disorders and polypharmacy. Medication should be reviewed regularly in order to avoid adverse drug reactions and medication-related hospital visits, but this is often not done. As part of our student-run clinic project, we investigated whether an interprofessional student-run medication review program (ISP) added to standard care at a geriatric outpatient clinic leads to better prescribing. In this controlled clinical trial, patients visiting a memory outpatient clinic were allocated to standard care (control group) or standard care plus the ISP team (intervention group). The medications of all patients were reviewed by a review panel (“gold standard”), resident, and in the intervention arm also by an ISP team consisting of a group of students from the medicine and pharmacy faculties and students from the higher education school of nursing for advanced nursing practice. For both groups, the number of STOPP/START-based medication changes mentioned in general practitioner (GP) correspondence and the implementation of these changes about 6 weeks after the outpatient visit were investigated. The data of 216 patients were analyzed (control group = 100, intervention group = 116). More recommendations for STOPP/START-based medication changes were made in the GP correspondence in the intervention group than in the control group (43% vs. 24%, P = < 0.001). After 6 weeks, a significantly higher proportion of these changes were implemented in the intervention group (19% vs. 9%, P = 0.001). The ISP team, in addition to standard care, is an effective intervention for optimizing pharmacotherapy and medication safety in a geriatric outpatient clinic.