Background Effective harm reduction work is needed to prevent and respond to the harms associated with image and performance enhancing drug (IPED) use and the diverse needs of IPED communities. Methods based around understanding and mapping complex systems have previously been applied to advance thinking on a range of complex health issues. We applied a systems perspective to explore factors that contribute to IPED-related harms in the UK and to identify harm reduction priorities. Methods An illustrative systems map was developed based on methods for mapping complex systems with expert stakeholders. Participants in two online workshops debated the important factors contributing to harm amongst people who use IPEDs and helped to refine and clarify the map. Discussions using the map reflected on where in the system intervention is needed and the policy implications. Results Stakeholders (n=18) identified 51 distinct factors as being important determinants of IPEDs-related harms, and the connections between them. These were grouped under nine domains that formed this system: identity, cognitive processes, beliefs about risk and harm, health and wellbeing, social environment, beliefs about healthcare, healthcare providers, interventions, and IPED markets. Four harm reduction priorities identified through reflexive discussion included providing a wider range of interventions, improving engagement between the IPED communities and healthcare professionals, new approaches to disseminating information in the community, and early intervention. Conclusion Systems mapping methods are a useful approach to engage stakeholders to discuss drug use issues. A comprehensive policy response is required to this complex issue that recognises diversity in IPEDs communities, their decision-making, and their intervention and service needs, as current approaches are failing to adequately address important areas of harm. Engaging with a wide range of stakeholders is critical to generate new insights that can help respond effectively to reduce the risk of health harms.