PURPOSE: To inform recommendations by the Canadian Task Force on Preventive Health Care on potentially inappropriate prescribing and over-the-counter (OTC) medication use among adults aged 65 years and older in primary care settings. This protocol outlines the planned scope and methods for a systematic review of the benefits and harms and acceptability of interventions to reduce potentially inappropriate prescriptions and OTC medication use. METHODS: De novo systematic reviews will be conducted to synthesize the available evidence on (a) the benefits and harms of interventions to reduce potentially inappropriate prescriptions and OTC medications compared to no intervention, usual care, or non- or minimally active intervention among adults aged 65 years and older and (b) the acceptability of these interventions or attributes among patients. Outcomes of interest for the benefits and harms review are all-cause mortality, hospitalization, non-serious adverse drug reactions, quality of life, emergency department visits, injurious falls, medical visits, and the number of medications (and number of pills). Outcomes for the acceptability review are the preference for and relative importance of different interventions or their attributes. For the benefits and harms review, we will search MEDLINE, Embase, and Cochrane Central Register of Controlled Trials for randomized controlled trials. For the acceptability review, we will search MEDLINE, Embase, PsycInfo, Cochrane Central Register of Controlled Trials, and the NHS Economic Evaluation Database for experimental and observational studies with a comparator. Websites of relevant organizations, other grey literature sources, and reference lists of included studies and reviews will be searched. Title and abstract screening will be completed by two independent reviewers using the liberal accelerated approach. Full-text review, data extraction, risk of bias assessments, and GRADE (Grading of Recommendations Assessment, Development and Evaluation) will be completed independently by two reviewers, with any disagreements resolved by consensus or by consulting with a third reviewer. The GRADE approach will be used to assess the certainty of the evidence for outcomes. DISCUSSION: The results of this systematic review will be used by the Canadian Task Force on Preventive Health Care to inform their recommendation on potentially inappropriate prescribing and OTC medication use among adults aged 65 years and older. SYSTEMATIC REVIEW REGISTRATION: PROSPERO (KQ1: CRD42022302313; KQ2: CRD42022302324); Open Science Framework ( https://osf.io/urj4b/ ).