Abstract Background people with dementia (PWD), and their carers, face challenges with medicines management activities. As interventions to support medicines management for PWD are developed, consideration must be given to the outcomes chosen to measure their effectiveness. A Core Outcome Set (COS) is a minimum set of outcomes to be measured in all trials in a particular clinical area, which seeks to reduce heterogeneity of outcome reporting across trials. Objective to develop a COS for trials assessing the effectiveness of medicines management interventions for PWD in primary care. Methods a comprehensive list of outcomes was compiled through a systematic review and semi-structured interviews with PWD (n = 18), their carers (n = 15), community pharmacists (n = 15) and general practitioners (n = 15). These outcomes were rated by a Delphi panel (n = 52) on a nine-point Likert scale from 1 (limited importance) to 9 (critical) during three sequential rounds of questionnaire distribution. The Delphi panel comprised participants with expertise in dementia and medicines management, including academics and healthcare professionals. An outcome was eligible for inclusion in the COS if ≥70% of participants rated it critical and <15% of participants rated it of limited importance. Results twenty-nine outcomes identified from the systematic review and stakeholder interviews were presented to the Delphi panel. Consensus was reached on 21 outcomes, of which the 7 most highly rated were recommended for inclusion in the COS. Conclusion this study used robust methodology to develop a COS for medicines management interventions for PWD. Future work should identify the most appropriate tools to measure these outcomes.