Google’s AI Overviews cite YouTube more frequently than any medical website when responding to health-related search queries, according to new research that raises concerns about the reliability of information shown to billions of users each month.
The study, conducted by the SEO firm SE Ranking, analysed more than 50,000 health queries made in Germany and found that YouTube accounted for 4.43% of all sources cited in AI Overviews – more than hospitals, government health portals or academic institutions. YouTube, which is owned by Google, was cited over 20,000 times, making it the single most referenced domain.
Researchers warned that YouTube is not a medical publisher and hosts content from a wide range of creators, including influencers with no medical training. While some videos are produced by hospitals or licensed professionals, the study found that these made up only a tiny fraction of all YouTube links cited.
AI Overviews appeared in more than 82% of health searches analysed. After YouTube, the most cited sources were German public broadcaster NDR, followed by medical reference sites such as MSD Manuals and NetDoktor.
Google said its AI summaries are designed to surface high-quality information from reputable sources, including expert-created YouTube content, and noted that the findings were based on German-language searches and may not apply elsewhere. However, independent experts said the results suggest a structural issue, with popularity and visibility outweighing medical authority in how health information is surfaced.
The findings follow earlier reporting that identified false and potentially dangerous medical advice in some AI Overviews, intensifying scrutiny of how the feature handles health information.
