Researchers are increasingly encouraged to co-produce research, involving members of the public, service users, policy makers and practitioners in more equal relationships throughout a research project. The sharing of power is often highlighted as a key principle when co-producing research. However, health and social care research, as with many other academic disciplines, is carried out within embedded hierarchies and structural inequalities in universities, public service institutions, and research funding systems—as well as in society more broadly. This poses significant challenges to ambitions for co-production. This article explores the difficulties that are faced when trying to put ideal co-production principles into practice. A reflective account is provided of an interdisciplinary project that aimed to better understand how to reduce power differentials within co-produced research. The project facilitated five workshops, involving researchers from different disciplines, health, social care and community development staff and public contributors, who all had experience in co-production within research. In the workshops, people discussed how they had attempted to enable more equal relationships and shared ideas that supported more effective and equitable co-produced research. Shared interdisciplinary learning helped the project team to iteratively develop a training course, a map of resources and reflective questions to support co-produced research. The gap between co-production principles and practice is challenging. The article examines the constraints that exist when trying to share power, informed by multidisciplinary theories of power. To bring co-production principles into practice, changes are needed within research practices, cultures and structures; in understandings of what knowledge is and how different forms of knowledge are valued. The article outlines challenges and tensions when co-producing research and describes potential ideas and resources that may help to put co-production principles into practice. We highlight that trying to maintain all principles of co-production within the real-world of structural inequalities and uneven distribution of resources is a constant challenge, often remaining for now in the realm of aspiration.

(1) The harm-reduction benefits of opioid agonist treatment (OAT) are well-established; however, the UK government’s emphasis on “recovery” may be contributing to a high proportion of people leaving treatment and low retention rates. We wanted to develop a rich and nuanced understanding of the factors that might influence the treatment journeys of people who use OAT. (2) We explored factors at each level of the socioecological system and considered the ways these interact to influence treatment journeys in OAT. We carried out semi-structured interviews with people who use OAT (n = 12) and service providers (n = 13) and analysed data using reflexive thematic analysis. (3) We developed three themes representing participant perceptions of treatment journeys in OAT. These were: (1) The System is Broken; (2) Power Struggles; and (3) Filling the Void. (4) Conclusions: The data suggest that prioritisation of treatment retention is important to preserve the harm-reduction benefits of OAT. Stigma is a systemic issue which presents multiple barriers to people who use OAT living fulfilling lives. There is an urgent need to develop targeted interventions to address stigma towards people who use OAT.