Google’s AI Overviews cite YouTube more often than any medical website when answering health-related searches, according to a new German study that raises concerns about how reliable these summaries are for users.
Researchers at SE Ranking analysed more than 50,000 health queries made via Google searches in Germany and found that YouTube accounted for 4.43% of all sources cited by AI Overviews — the highest share of any single domain. By comparison, no hospital network, government health authority or academic institution came close. Other frequently cited sources included Germany’s public broadcaster NDR and medical reference sites such as MSD Manuals and NetDoktor.
The findings are notable because YouTube, which is owned by Google, is not a medical publisher and hosts content from both qualified professionals and untrained influencers. The researchers warned that this suggests popularity and visibility may outweigh medical authority in how AI Overviews assemble health information.
AI Overviews appeared in more than 82% of the health searches studied and are seen by an estimated 2 billion users each month. The research follows earlier reporting that found Google’s AI summaries had, in some cases, provided misleading or potentially harmful medical information.
Google said the results should not be generalised beyond Germany and argued that many highly cited YouTube videos come from hospitals, clinics and licensed professionals. However, the researchers noted that these accounted for less than 1% of all YouTube links cited, meaning the credibility of the majority remains unclear.
Experts say the study suggests the risks linked to AI-generated health advice are systemic, not isolated, and call for greater reliance on recognised medical and public health authorities.
