In a letter to dietary-supplement maker Zarbee’s Inc., the U.S. Food and Drug Administration (FDA) has warned that “liking” or commenting on testimonials posted to the company’s Facebook page could amount to endorsing the testimonial, resulting in sanctions for medicinal claims not approved by FDA.

On the Zarbee’s company Facebook page, customers posted praise about the therapeutic value of various products, including Zarbee’s Naturals Children’s Cough Syrup. Zarbee’s then “Liked” those posts or added appreciative comments despite the fact that the claims in the posts would subject the products to FDA oversight as drugs. “Your products are not generally recognized as safe and effective for the above referenced uses and, therefore, these products are ‘new drugs’” under the Federal Food, Drug, and Cosmetic Act, the agency told Zarbee’s.

According to FDA draft guidance documents on drug companies’ social media usage, companies are generally not responsible for content posted by third parties about their products if the company has not endorsed the content.