On Monday, the FDA told the makers of every GLP-1 drug to add a warning about a rare eye condition called NAION to their labels. The order covers about a dozen drugs, including Ozempic, Wegovy, Mounjaro and Zepbound. NAION happens when blood flow to the front of the optic nerve drops. It causes sudden, painless vision loss, usually in one eye. There's no known treatment. The FDA began its review after a 2024 study linked semaglutide, the drug in Ozempic and Wegovy, to the condition. In the agency's review of 126 clinical trials, NAION showed up at about 6.4 cases per 100,000 patient-years on a GLP-1, compared with 3.8 on placebo or other drugs. When the FDA looked at animal data, it couldn't identify how the drugs might cause it. Europe's drug regulator listed NAION as a very rare side effect of semaglutide in June 2025.

The Warning Is Right, but Most People Should Stay on the Drug

Eye doctors say patients should know the signs, and the drugs' benefits still win out for most people.

Patients need to know what to watch for. Dr. Manjot Gill, a professor of ophthalmology at Northwestern University's Feinberg School of Medicine, called the warning appropriate. She said it's mostly about awareness, so people who notice vision changes get to an eye doctor fast. The FDA says anyone with sudden vision loss in one eye, blind spots or blurry vision should call a doctor right away.

The damage usually doesn't heal. Dr. Joseph Rizzo, a neuro-ophthalmologist at Mass Eye and Ear who co-wrote the 2024 study, says patients rarely get much vision back. He also warns that mild loss in one eye says nothing about the other. "You could have mild visual loss in one eye, and then the next eye could be severe," he told CBS News.

Most people should keep taking it. Rizzo calls the drugs "profoundly beneficial to a large number of people." He has said he wouldn't use his own findings to tell patients to stop. In August, the American Academy of Ophthalmology and the North American Neuro-Ophthalmology Society said they don't fully support Europe's advice to stop the drug in everyone who develops NAION. They said routinely stopping it could hurt patients who need it. Gill says the benefits "far outweigh the exceedingly low rate of this complication developing." "We don't want patients to really get overly concerned and anxious and to stop these medications," she told NBC News.

But the Drugs Haven't Been Shown to Cause It

Novo says the data don't establish cause and effect, and analysts call the absolute risk low.

The data don't prove cause and effect. Novo Nordisk makes Ozempic and Wegovy. Liz Skrbkova, who leads its U.S. media relations, said the company "continues to believe the data do not establish a cause-and-effect relationship." Novo pointed to a 2026 study of more than 90,000 trial participants that found no link between its drugs and NAION. It said so in a statement to The Washington Post before the announcement, adding that semaglutide's "benefit-risk profile" "remains favorable."

The FDA's trial review turned up only a handful of cases. It found just 15: 10 in people on a GLP-1 and five on placebo. The FDA also studied real-world patients with diabetes. There, GLP-1 users' risk wasn't significantly different from the risk for people on SGLT-2 drugs like Jardiance. Their risk did look higher than for people on DPP-4 drugs like Januvia. The FDA itself notes that GLP-1 patients often have diabetes, obesity, sleep apnea and high blood pressure. Each of those raises NAION risk on its own, so the case reports are hard to interpret. Analysts at BMO wrote Monday that they see "limited risk" to Novo's and Lilly's obesity business "given rarity in incidence."

Lilly says nothing here points at its drugs. Eli Lilly, which makes Mounjaro and Zepbound, said the FDA's notice covers every GLP-1 and "does not reference any findings specific to Lilly medicines." Lilly says it will respond to the FDA promptly.

Eye doctors' own groups say causation isn't proven either. Those same groups said "causality has not been established." They said the risk may be about twice as high, mostly with semaglutide.

And for Patients Already Hurt, It Came Too Late

Plaintiffs' lawyers say patients should have heard about this risk sooner.

Regulators flagged the risk well before Monday. The FDA put GLP-1s and NAION on its list of potential safety signals for late 2024. Europe had already warned about it in June 2025. As of late September, U.S. labels for Ozempic, Wegovy, Rybelsus and Mounjaro didn't mention NAION. Now the FDA has ordered drugmakers to add it.

Hundreds of patients are already suing. The Lanier Law Firm, which represents plaintiffs, counted about 278 federal lawsuits as of Nov. 3. They say the drugmakers failed to warn about vision loss. NPR counted 247 in October. U.S. District Judge Karen Marston is overseeing them in federal court in Philadelphia. Jonathan Orent is a Motley Rice attorney and one of the lead court-appointed lawyers in the GLP-1 lawsuits. "These warnings would have made a difference in the lives of real people," he told NPR in October, before Monday's order. Novo has called the suits "without merit." Lilly told NPR in October that it will "vigorously defend against these claims."

Some people lost their sight before anyone told them. Todd Engel started Ozempic in early 2023 and lost sight in his right eye that winter. He didn't know about the risk, so he kept taking it. About a year later, he lost sight in his left eye too. "This could have been prevented, if we only knew," his wife, Shelley Engel, told NPR. Drugwatch is a legal-information site that partners with law firms. Whitney Di Bona, an attorney there, said Monday that new patients "will have information that earlier patients never got."

Where This Lands

The FDA says people should know the signs and get help fast. Eye doctors like Rizzo and Gill say most patients should keep taking the drugs. Novo says the evidence doesn't show its drugs cause NAION. The FDA's trial review found just 15 cases. Plaintiffs' lawyers say the warning came too late for patients who already lost their sight. Lilly says the warning doesn't point to its drugs in particular. The lawsuits keep moving in Philadelphia.

Sources