Most medical YouTube videos factually incorrect, even ones by doctors

Over 60 percent of the Korean-language YouTube videos with medical content have very low to no credibility, even those created by professional physicians, according to a recent analysis by researchers at the National Cancer Center.

The study led by Kang Eun-kyo, an assistant professor of public health and artificial intelligence, also found that videos with the lowest credibility got substantially more views than the most medically relevant ones.

Kang's team reviewed 309 videos with a median of 164,454 views and a median length of 19 minutes in June 2025. All videos had at least 10,000 views, lasted at least one minute, contained specific comments, and three-fourths of them were created by physicians.

The videos were assessed on the level of credibility, from A (high certainty from systematic reviews and/or guidelines), B (moderate certainty from randomized clinical trials, cohort studies and high-quality observational studies with clear citations), C (low certainty from limited observational studies, physiological mechanisms or case series without critical appraisal), to D (very low or no certainty from anecdotal evidence).

Some 62.5 percent of the videos received a D grade, while only 19.7 percent got an A. The rest got a B (14.6 percent) and a C (3.2 percent).

It was found that D-graded videos were associated with 34.6 percent higher view counts than grade A videos.

"A substantial credibility-evidence gap was found in physician-generated video-sharing content, where medical authorities often legitimized claims lacking robust empirical support," the study concluded.

"These findings emphasize the need for evidence-based content guidelines and enhanced science communication training for health care professionals to maintain scientific integrity in digital health information."

The study was published in the JAMA Network Open, a monthly open-access medical journal published by the American Medical Association.

The findings raise a potential red flag in one of the most tech-savvy countries in the world, where an increasing proportion of the population relies on YouTube videos for medical information.

Researches show that the public is greatly impacted by what they see on YouTube. A 2021 study on the effects of medical YouTube videos found that viewers' health behaviors are more likely to be affected by their perceived competence, influence and likeability of the content creators.

"Results of analysis indicated that creators’ reputation perceived by viewers and content attributes are positively correlated to intentions of health behavior, which was mediated by information reliability," the researchers noted in the study published by the Korean Academic Society for Public Relations.