Co-produced practices and publications in the healthcare sector are gaining momentum, since they can be a useful tool in addressing the sustainability and resilience challenges of health systems. However, the investigation of positive and, mainly, negative outcomes is still confused and fragmented, and above all, a comprehensive knowledge of the metrics used to assess these outcomes is lacking. To fill this gap, this study aims to systematically review the extant literature to map the methods, tools and metrics used to empirically evaluate co-production in health services. The search took place in six databases: Scopus, Web of Science, Psych INFO, PubMed, Cochrane and CINAHL. A total of 2311 articles were screened and 203 articles were included in the analysis, according to PRISMA guidelines. Findings show that outcomes are mainly investigated through qualitative methods and from the lay actor or provider perspective. Moreover, the detailed categorisation of the quantitative measures found offers a multidimensional performance measurement system and highlights the impact areas where research is needed to develop and test new measures. Findings should also promote improvements in empirical data collection on the multiple faceted co-produced activities and spur the consciousness of the adoption of sustainable co-productive initiatives.