The U.S. Food and Drug Administration (FDA) on Monday, November 9, ordered every GLP-1 diabetes and weight-loss drug sold in the United States to carry new label information about a potential increased risk of a rare but serious eye condition that can cause sudden, permanent vision loss. The requirement applies to the whole class of glucagon-like peptide-1 receptor agonists (GLP-1 RAs) — including Novo Nordisk's Ozempic, Rybelsus and Wegovy and Eli Lilly's Mounjaro and Zepbound — and the information must be added to the 'Warnings and Precautions' section of each drug's labelling, the agency said in a Drug Safety Communication.
Source: U.S. Food and Drug Administration
The condition is non-arteritic anterior ischemic optic neuropathy, known as NAION. It occurs when blood flow to the front part of the optic nerve — the nerve that carries visual signals from the eye to the brain — is suddenly reduced. NAION is a common cause of sudden, painless vision loss, usually in one eye, and the damage may lead to permanent impairment of sight in some cases. The FDA said the underlying cause of the condition is not completely understood.
The FDA's own meta-analysis pooled 126 clinical trials across the GLP-1 development programmes, covering 134,253 patients — 78,217 GLP-1 users and 56,036 patients on a comparator — and 288,879 person-years of exposure. Reviewers identified 15 probable NAION events: 10 in patients treated with a GLP-1 drug, five in patients given a placebo, and none in patients taking other non-GLP-1 glucose-lowering medicines. That produced an incidence rate of 6.4 events per 100,000 person-years on GLP-1 drugs, against 3.8 per 100,000 on comparator treatment — a real difference, but one built on very small absolute numbers.
A second FDA study, a retrospective cohort in the agency's Sentinel real-world data network, compared adults with type 2 diabetes who started a GLP-1 drug between 2019 and 2024 with patients who started an SGLT-2 inhibitor or a DPP-4 inhibitor. NAION rates there ranged from 26 to 32 events per 100,000 person-years across the groups. There was no statistically significant increase against SGLT-2 inhibitors (hazard ratio 1.19), but an increased risk was observed against DPP-4 inhibitors (hazard ratio 1.43), the FDA said.
How the review began
The question first drew wide attention in July 2024, when Hathaway and colleagues published a study in JAMA Ophthalmology titled 'Risk of Nonarteritic Anterior Ischemic Optic Neuropathy in Patients Prescribed Semaglutide.' The FDA said it identified several limitations in that study but decided a full assessment was warranted. The agency then reviewed clinical trial data, animal data and postmarketing data, including reports in its adverse-event system, observational studies and case reports. It noted that the adverse-event reports were hard to interpret because the risk factors for NAION often overlap with conditions common in people treated with GLP-1 drugs, and that its review of animal data did not identify a mechanism by which the drugs could raise NAION risk.
Published observational research pointed in a similar direction. A large study published in 2025 tracked nearly 175,000 diabetic patients treated with semaglutide and an equal number taking non-GLP-1 medications, and found that the risk of NAION more than doubled after two years of treatment with a GLP-1 drug compared with diabetes medicines from other classes, Reuters reported. The FDA said methodologically rigorous observational studies consistently reported an increased risk in patients with type 2 diabetes who started GLP-1 drugs, generally consistent with its own trial and Sentinel findings, and that NAION cases have now been reported for every GLP-1 product currently marketed.
Source: Reuters
Europe moved first
European regulators acted earlier. Last year, the European Medicines Agency's safety committee said NAION may affect up to 1 in 10,000 people taking semaglutide — the active ingredient in Ozempic, Wegovy and Rybelsus — for at least one year, the first time a regulator had confirmed the side effect. Novo Nordisk subsequently added a NAION warning to the European labels of Wegovy and Ozempic. In Denmark, four patients who experienced vision loss after using Novo's GLP-1 drugs were granted compensation by the Danish Patient Compensation association, Reuters reported. The FDA put the background rate of NAION at 2.3 to 10.2 cases per 100,000 people a year among adults over 50.
The FDA advises prescribers to tell patients to report immediately any sudden, painless loss of vision, a visual-field deficit or any other visual disturbance in one eye, and to refer suspected NAION cases promptly to an ophthalmologist. Symptoms reported with NAION include vision loss noticed on waking, blind spots, tunnel vision, distorted colours and hazy or blurry patches. The warning is a labelling change — not a recall, a ban or a boxed warning — and patients should not stop a prescribed GLP-1 medicine without speaking to their clinician, since diabetes and obesity carry serious risks of their own.
The companies respond
Eli Lilly noted that the FDA communication covers the whole class. 'FDA's drug safety communication applies to all medicines with GLP-1 RA activity and does not reference any findings specific to Lilly medicines. We are carefully evaluating the update and will respond to FDA promptly,' a Lilly spokesperson said. Novo Nordisk maintained its position: 'Novo continues to believe the data do not establish a cause-and-effect relationship and we remain confident in the benefit-risk profile of our GLP-1 medicines,' a Novo spokesperson said. Citi analyst Geoff Meacham said the FDA action 'may temporarily increase patient and investor concern, but the rarity of NAION and substantial weight, glycemic, cardiovascular, renal, and sleep apnea benefits should preserve a favorable benefit-risk profile and limit changes to prescribing.'
Source: Reuters
The decision matters far beyond the label. GLP-1 medicines are among the best-selling drugs in the world and are widely used across the United States for type 2 diabetes and weight management — conditions that are especially common in South Asian and Punjabi diaspora families, many of whom will now hear about the eye warning from their pharmacist or doctor before they read about it anywhere else. Although public attention has centred on semaglutide, the FDA applied the change across the entire class, which also includes older medicines such as liraglutide and dulaglutide and the dual GIP/GLP-1 drug tirzepatide.
What is solid
- The FDA is requiring NAION information in the Warnings and Precautions section of the labelling of all GLP-1 receptor agonists sold in the US.
- In the FDA's trial meta-analysis, NAION occurred at 6.4 events per 100,000 person-years on GLP-1 drugs versus 3.8 on comparator treatment, based on 15 probable cases.
- NAION can cause sudden, painless and sometimes permanent vision loss, usually in one eye.
What is only claimed
- Whether GLP-1 drugs cause NAION has not been established: the FDA describes a 'potential increased risk', its animal-data review found no mechanism, and Novo Nordisk says the data do not establish a cause-and-effect relationship.
- The FDA's Sentinel study found no statistically significant increase versus SGLT-2 inhibitors, even though it found an increase versus DPP-4 inhibitors.
What happens next: the drugmakers must now update their U.S. labels; the FDA has not announced a date by which the new wording must appear. Prescribers are expected to discuss the eye risk with patients starting or continuing treatment, and the class-wide warning is also likely to feature in continuing U.S. litigation over the drugs — as of September, at least 4,000 consolidated claims alleging GLP-1 drugs caused vision loss had been recorded, according to court records cited in trade coverage. For the millions of Americans taking these medicines, the practical message from regulators is narrow but urgent: a sudden change in vision in one eye is a reason to seek care the same day, not to wait and see.