Social networks are a “Wild West” of medical misinformation, a study has found. More than one in four comments on Facebook diabetes communities is promotional in nature, generally for unapproved products, Harvard and Brigham and Women’s Hospital researchers said.

Though the researchers found “tentative support” for the health benefits of social media in the management of chronic disease—reporting patients sharing valuable insights into their conditions that they wouldn’t get from their doctor and providing each other emotional support – the volume of dubious information raises red flags.

It could also offer a rationale for greater provision of legitimate medical information by companies through social media, proving the old PR maxim that if you’re not telling your story, someone else will tell it for you—or in this case, sell your patients snake oil in place of proven therapies.

The study’s authors looked at the 15 largest Facebook communities for diabetes patients and caregivers. In addition to the promotional comments, the researchers also identified “numerous instances of surveys, marketing pitches and efforts to recruit patients for clinical trials where the true identity of the poster could not be confirmed.”

The 15 sites had an average of 9,289 participants, and researchers evaluated 690 individual postings by 480 unique users. Two thirds were individuals describing their personal experiences with managing diabetes. Nearly a quarter consisted of personal info unlikely to be shared between patients and docs, such as patients discussing managing carbs from alcoholic beverages. Twenty-nine percent of posts were by patients providing emotional support to others, while 13% were providing specific feedback to info requests by fellow patients. Twenty-seven percent “featured promotional activity and first-person testimonials around non-FDA approved products and services.”

“Clinicians should be aware of these strengths and limitations when discussing sources of information about chronic disease with patients,” said senior author William Shrank, MD, MSHS. “Policy makers should consider how to assure transparency in promotional activities, and patients may seek social networking sites developed and patrolled by health professionals to promote accurate and unbiased information exchange.”

“There certainly are public health benefits that can be garnered from these sites,” added Shrank, “but patients and doctors need to know it is really the Wild West out there.”

The study was underwritten by CVS Caremark and published online in the Journal of General Internal Medicine.