Content quality and reliability of mental health videos for cancer patients on social media platforms: a cross-sectional study.

PURPOSE: Cancer patients are increasingly turning to social media, an indispensable source of health information, for mental health support. However, the quality and reliability of widely available mental health videos remain largely unevaluated. This study aimed to systematically evaluate and compare the quality and reliability of mental health videos on social media platforms. METHODS: A cross-sectional study was conducted. We systematically searched and screened the top 100 videos for each of three topics (mindfulness, relaxation techniques, music therapy) on both YouTube and TikTok. Video characteristics, uploader identity, and content format were classified using a standardized framework. Two independent raters assessed video quality using the Global Quality Scale (GQS) and reliability using the modified DISCERN (mDISCERN) instrument. Statistical analyses included Kruskal-Wallis H tests with post-hoc comparisons and K-means clustering analysis. RESULTS: A total of 600 mental health-related videos screened. Ultimately, 450 eligible videos (187 from YouTube, 263 from TikTok) were included for analysis. YouTube's ecosystem was more institutional, while TikTok was dominated by general users. Videos from healthcare professionals (doctors and non-physician mental health professionals) demonstrated significantly higher reliability scores on both platforms. Regarding audience engagement, highly popular videos on YouTube exhibited significantly lower reliability, whereas engagement and quality were unrelated on TikTok. Content format performance was platform-specific; integrated guidance was reliable on YouTube but scored lowest on TikTok (GQS, p = 0.001 vs practical guidance). Music therapy videos were consistently the lowest-performing topic. CONCLUSION: While healthcare professionals are the most reliable sources of mental health information on both YouTube and TikTok, their content is not necessarily the most visible or engaging. The disconnect between popularity and informational quality highlights the need for critical media literacy among patients and calls for platform-level innovations to prioritise reliable health information. TRIAL REGISTRATION: Not applicable.