Google’s AI Overviews feature most often cites YouTube when answering health-related search queries, according to a German study that analysed more than 50,000 searches and raises concerns about how medical information is presented to users.
Researchers at SE Ranking found that YouTube accounted for 4.43% of all sources cited in AI Overviews for health queries, making it the single most referenced platform. No hospital network, government health body or academic institution came close. The next most cited sources were German public broadcaster NDR.de and medical reference site Msdmanuals.com.
The study, based on German-language searches conducted in December 2025, found AI Overviews appeared in more than 82% of health searches. Researchers warned that YouTube is not a medical publisher and hosts content from both qualified professionals and untrained influencers, making reliability uneven.
Google said AI Overviews are designed to surface high-quality information from reputable sources, including expert-created YouTube content, and argued the findings could not be generalised beyond Germany. However, independent experts said the study suggests structural risks, with popularity and visibility outweighing medical authority in how health information is surfaced.
The findings follow earlier reporting that Google’s AI health summaries have, in some cases, contained misleading or potentially harmful medical advice.
