U.S. regulators warn of a potential rare risk of blindness associated with GLP-1 drugs.

US Food and Drug Administration data show that among people taking this class of drugs, about 6 cases of non-arteritic anterior ischemic optic neuropathy occur per 100,000 people each year. The FDA is requiring manufacturers of blockbuster GLP-1 drugs such as Ozempic and Zepbound to add related warning labels; this eye condition can cause permanent vision loss. In a safety notice issued on Monday, the FDA said GLP-1 drugs may increase the risk of developing NAION, a condition that causes partial blindness. Patients have sued drugmakers, alleging that the drugs caused their vision damage; major pharmaceutical companies including Novo Nordisk and Eli Lilly are defending the cases, saying existing research has not confirmed that GLP-1 drugs trigger NAION. An Eli Lilly spokesperson said patient safety is the company's top priority, that it is evaluating the FDA's latest requirement, and that it will respond soon. Novo Nordisk and Sanofi, which also have approved GLP-1 products, did not immediately comment.