Health professions educators often use social media to share knowledge; however, it is unclear what specific dissemination and knowledge translation (KT) processes are occurring and the implications of this sharing for health professions education (HPE). This study explored how educators have used social media as a mechanism of dissemination and KT in the literature. A critical scoping review methodology, informed by Engeström's Activity Theory, was employed. Twelve databases were searched and studies that: (a) addressed health professions educators; (b) described the use of social media for dissemination or KT; (c) focused on a regulated health profession; (d) focused on undergraduate or graduate education; and (e) were published in English or French between 2011 and 2021 were included. Data were analyzed using numerical and qualitative content analyses. Of the 4859 articles screened, 37 were eligible for inclusion. Social media may facilitate knowledge sharing in HPE, but there is a lack of conceptual clarity on what is meant by 'dissemination' and 'KT'. Who is responsible for sharing knowledge, what knowledge is being shared, and the target audiences are not always clear. Multiple factors (e.g., affordances, opportunity costs) influence how social media is used as a mechanism of dissemination, and it remains unclear whether and how it is used as a mechanism of KT. Concepts like KT and dissemination, which are often borrowed from other disciplines, must be critically evaluated for their relevance and suitability if they are to be appropriately applied to HPE and in particular to social media. Educators looking to use social media to teach students about KT should consider whether this use of technology truly aligns with their stated learning outcomes.