The U.S. Food and Drug Administration has issued a warning letter to MannKind Corp. for sharing a misleading post about the company’s drug Afrezza on its Facebook page.

Afrezza is an inhalable insulin treatment for diabetic patients. According to the FDA, MannKind overstated the benefits of the drug and misrepresented the health risks it poses for patients with chronic lung disease.

“Specifically, in the context of a promotional piece for Afrezza, the post claims that ‘Afrezza Inhalation Powder’ ‘will help your body work its best and protect you from health complications’ with ‘no drama,’ when this may not be the case,” the FDA wrote in the letter. “Afrezza is associated with multiple serious, and potentially life-threatening risks, such as those contained in the product’s boxed warning. By suggesting that there are no risks associated with use of Afrezza, this post is misleading with respect to the drug’s safety.”

The post appeared on the Westlake Village biotech firm’s Facebook page from Feb. 9 to March 19. The FDA issued the warning on Oct. 5.

The FDA requested that MannKind immediately cease the misleading branding and provide a written response detailing how it plans to comply with the request.

Shares of MannKind (MNKD) dropped 12 cents, or 6 percent, on Monday to close at $1.87 on the Nasdaq.