Background People with mental disorders experience persistent stigma and social exclusion, often reinforced within healthcare settings. Medical students represent a key population for transforming these dynamics, as they begin shaping professional norms early in their training. This study analyzes messages produced by first-year medical students regarding the social inclusion of people with mental disorders, within a transmedia educational strategy aimed at promoting human rights and reducing stigma. Methods A qualitative study with an interpretive–critical approach was conducted using an action-research design. The activity was embedded in a first-semester elective course at a medical school in Colombia. After a film-based discussion on prejudice, 404 students (69% women, aged 16–18) worked in groups to create 75 text-based messages for social media. Data were analyzed using inductive thematic analysis, complemented by a word frequency analysis to identify commonly used terms. Results Four categories emerged: appealing to empathy, affirming human worth, reframing difference, and promoting attitudinal change. Messages were brief, emotionally oriented, and adapted to social media formats. Non-clinical terms such as “crazy” and “madness” predominated over clinical or rights-based language. While students expressed values of respect and inclusion, their messages remained at an interpersonal and moralizing level, with limited engagement with structural determinants of exclusion or the legal rights of people with mental disorders. Conclusions First-year medical students produce inclusion messages that are emotionally resonant but show limited critical engagement with the systemic mechanisms of stigma. Strengthening educational strategies grounded in human rights, person-centered language, and structural approaches to stigma may enhance the transformative potential of student-generated digital content. Early medical education represents a key opportunity to move beyond paternalistic framings toward a focus on citizenship and collective rights in mental health advocacy. Trial registration Not applicable.