- The warning covers the whole drug class. The U.S. Food and Drug Administration said Monday it is requiring makers of all GLP-1 medications, including Novo Nordisk’s Wegovy and Ozempic and Eli Lilly’s Zepbound and Mounjaro, to add a warning about a potential increased risk of NAION, CNBC reported.
- The trial data show a higher rate. An analysis of 126 trials with more than 134,000 patients found 6.4 NAION cases per 100,000 patient-years among GLP-1 users versus 3.8 among patients on other treatments or placebo, about 1.7 times the rate by our calculation.
- Causation remains unproven. NAION, a rare condition caused by decreased blood flow to the front of the optic nerve, can lead to sudden and even permanent vision loss, but the FDA said a causal relationship has not been established, and diabetes itself is a known risk factor.
- Wall Street sees limited commercial damage. Citi analysts said the class-wide label change is “likely to attract attention but should have limited impact on GLP-1 uptake,” while Novo Nordisk said the data “do not establish a cause-and-effect relationship.”
What Happened?
The FDA’s decision follows a review of clinical trials, real-world patient data and published studies, and the agency said NAION cases have been reported for all currently marketed GLP-1 products. It identified 15 probable NAION events in trials, 10 in GLP-1 patients and five in placebo patients. Real-world data showed a statistically significant increase in risk versus DPP-4 inhibitor users but not versus SGLT-2 inhibitor users such as those taking Jardiance and Farxiga, though observational studies consistently found higher risk for type 2 diabetes patients starting a GLP-1 versus either class. CNBC said it had reached out to Eli Lilly for comment.
Why It Matters?
A class-wide safety label can shape how doctors and patients weigh treatment. The FDA action goes further than European and British regulators, whose warnings focused only on semaglutide; the European Medicines Agency said in June 2025 that NAION may affect up to 1 in 10,000 people taking it. Semaglutide and tirzepatide already carry warnings about diabetic retinopathy, and many GLP-1s carry a boxed warning over potential thyroid tumor risk seen in rodents. Citi said the drugs’ weight, glycemic, cardiovascular, renal and sleep apnea benefits should preserve a favorable benefit-risk profile.
What’s Next?
Investors will watch for updated labels from Novo Nordisk and Eli Lilly and any change in prescription trends as patients and doctors digest the warning. Citi expects only a temporary rise in patient and investor concern. Further research into whether GLP-1s directly cause NAION, rather than underlying diabetes, will determine whether the warning becomes a bigger issue.
Affected Tickers and Coins: NVO, LLY
Source: CNBC
