The FDA is requiring the makers of every GLP-1 drug on the U.S. market, Ozempic, Wegovy, Mounjaro and Zepbound among them, to warn of a potential increased risk of an “eye stroke” that can cause sudden, permanent vision loss in one eye. The condition is non-arteritic anterior ischemic optic neuropathy, or NAION.
The agency’s Nov. 9 drug safety communication puts the language in the Warnings and Precautions section of labels for a dozen products, from Byetta, approved in 2005, to Lilly’s newly approved Foundayo. FDA said it “concluded that there is a potential increased risk of rare NAION events in patients taking GLP-1 RAs” and told clinicians to consider discontinuing the drug in patients who develop NAION, unless the benefits clearly outweigh the risk.
FDA’s review of 126 randomized trials covering 134,253 patients found 15 probable NAION events: 10 among patients on GLP-1 drugs, 5 on placebo and none on other glucose-lowering drugs. That works out to 6.4 cases per 100,000 person-years on GLP-1 drugs against 3.8 for comparators. The agency puts the background rate for adults over 50 at 2.3 to 10.2 cases per 100,000 people a year.
A separate FDA Sentinel cohort of type 2 diabetes patients from 2019 to 2024 saw 26 to 32 cases per 100,000 person-years. Compared with SGLT-2 inhibitors, the GLP-1 increase was not statistically significant (hazard ratio 1.19, 95% confidence interval 0.91 to 1.54). Compared with DPP-4 inhibitors, it was: a hazard ratio of 1.43 (1.02 to 2.01).
The agency said published observational studies that it judged methodologically rigorous consistently found higher NAION risk on GLP-1 drugs than on DPP-4 or SGLT-2 inhibitors. Its review of animal data identified no mechanism linking the drugs to the condition, and it called adverse event reports hard to interpret because NAION’s risk factors overlap with conditions common among GLP-1 users. FDA noted limitations in the 2024 semaglutide study by Hathaway and colleagues in JAMA Ophthalmology that prompted the review.
The European Medicines Agency’s safety committee concluded in June 2025, well ahead of FDA, that NAION is a very rare side effect of semaglutide, affecting up to 1 in 10,000 people, and recommended label updates for Ozempic, Rybelsus and Wegovy. That review began in January 2025, after two observational studies suggested higher risk and two others did not.
Eli Lilly, which makes Mounjaro and Zepbound, said FDA’s notice “applies to all medicines with GLP-1 RA activity and does not reference any findings specific to Lilly medicines,” in a statement to the Daily Mail. The company said it is “carefully evaluating the update and will respond to FDA promptly.”
FDA tells patients to watch for sudden, painless vision loss in one eye, often noticed on waking, along with blind spots, tunnel vision, color distortion or blurry central vision. Anyone with those symptoms should contact a health care professional right away, and anyone who has had NAION should discuss with a clinician whether to keep taking the drug. Risk factors include smoking, diabetes, high blood pressure, sleep apnea, anemia and kidney disease, and once NAION strikes one eye, the other is at increased risk.
