Some 70 percent of Americans report that health information they find on the internet influences their decision about how to treat a medical condition, according to a study by the Pew Research Center. But how to know if it’s accurate? NYU Langone Health researchers set out to find some answers by reviewing the most popular YouTube videos about prostate cancer. YouTube, the largest video-sharing social media platform, is viewed by 73 percent of adults in the United States.

Stacy Loeb, MD, who chairs a panel of social media experts for the American Urological Association, led a team of investigators who examined the site’s first 150 videos in a search on prostate cancer, out of more than 600,000 on that topic. They evaluated each one for accuracy, level of misinformation, and commercial bias. Because prostate cancer is one of the most common forms and a broad array of treatment options are available with different benefits and risks, advice on the topic is in high demand. “Patients who feel that they aren’t getting all the information they need from their physician are more likely to consult online sources,” Dr. Loeb explains, “but that’s where they might be exposed to misinformation.”

The study, published online in the journal European Urology, found that 77 percent of the videos analyzed had biased or potentially misinformative content in either the video itself or its comments section. But the more surprising finding, says Dr. Loeb, was the discord between scientific quality and user engagement. “Just because a video gets a lot of ‘likes’ or ‘thumbs up’ doesn’t necessarily mean it’s accurate,” she explains. “Some of the most reliable videos showed physicians at their desks recorded on a phone, as opposed to other snappy videos that were commercially biased.”

As long as social media platforms remain unregulated, health consumers are on their own. To help them feel more empowered, Dr. Loeb offers a checklist of questions to consider when evaluating medical videos online:

When was it made?

Videos older than one year may no longer be valid because medicine is always evolving. Sort your searches by date.

Who made it?

If no source is cited or you’ve never heard of the one that is, the information may not be authoritative. Consult reputable organizations and government agencies, such as the National Institutes of Health.

Is it balanced?

When there’s no mention of risks or multiple treatment options, the content is probably biased.

Is it realistic?

Beware of claims such as “miracle cure” and “natural remedy.” If it sounds too good to be true, it probably is.