FDA Adds GLP-1 Eye-Risk Warning After Reviewing 126 Clinical Trials

The US Food and Drug Administration (FDA) has ordered manufacturers of glucagon-like peptide-1 (GLP-1) medicines to update their product labelling to warn about a potential increased risk of a rare eye condition that can cause sudden vision loss.

The requirement covers medicines including Novo Nordisk’s Ozempic and Wegovy, and Eli Lilly’s Mounjaro and Zepbound. The FDA is requiring the companies responsible for all GLP-1 receptor agonist medicines to include information about non-arteritic anterior ischaemic optic neuropathy (NAION) in the Warnings and Precautions section of their product labelling.

The condition occurs when blood flow to the front part of the optic nerve is reduced. It can cause sudden, painless loss of vision in one eye and may result in permanent impairment. The underlying cause is not fully understood.

The FDA announced the labelling requirement on 9 November after reviewing clinical trial findings, animal data, post-marketing reports and observational research. The agency described the association as a potential increased risk, rather than establishing a direct cause-and-effect relationship.

FDA review identifies a rare but potential safety risk

The regulator’s analysis included 126 randomised, controlled clinical trials involving 134,253 participants. Of these, 78,217 received GLP-1 medicines and 56,036 received comparator treatments.

The review identified 15 probable NAION cases: 10 among patients receiving GLP-1 medicines and five among those receiving placebo. No cases were identified among patients taking non-GLP-1 glucose-lowering medicines in the relevant trial analysis.

The resulting incidence rate was 6.4 cases per 100,000 person-years among GLP-1 users, compared with 3.8 per 100,000 person-years among comparator patients.

The FDA also examined real-world data from adults with type 2 diabetes who began treatment between 2019 and 2024. In that analysis, the agency found no statistically significant increase in NAION risk among GLP-1 users compared with patients taking SGLT-2 inhibitors. However, the comparison with DPP-4 inhibitors showed an increased risk.

The agency said observational studies also provided evidence of an association, while noting that underlying risk factors can complicate the interpretation of reports involving people taking these medicines.

Which medicines are covered by the warning?

The requirement applies across the GLP-1 receptor agonist class, not only to medicines used specifically for weight reduction.

Affected products include semaglutide medicines Ozempic, Wegovy and Rybelsus, as well as liraglutide-based treatments such as Victoza and Saxenda. Eli Lilly’s tirzepatide medicines Mounjaro and Zepbound are also included. The FDA’s list covers other approved medicines in the class, including Trulicity and the newer oral treatment Foundayo.

Tirzepatide acts on both GIP and GLP-1 receptors, while semaglutide is a GLP-1 receptor agonist. The FDA’s labelling action reflects its assessment of the wider group of medicines with GLP-1 receptor activity.

The decision is relevant to manufacturers across the category because the agency is requiring all relevant application holders to update their warnings and precautions information.

Novo Nordisk and Eli Lilly respond to the FDA action

Eli Lilly said it was evaluating the FDA update and would respond to the regulator. The company added that the safety communication applied to medicines with GLP-1 receptor activity and did not refer to findings specific to Lilly products.

Novo Nordisk said the available data did not establish a cause-and-effect relationship between its medicines and NAION. The company also said it remained confident in the benefit-risk profile of its GLP-1 treatments.

The regulatory action comes as these medicines are used across a range of approved indications, including type 2 diabetes and weight management. Certain products also have approved uses relating to cardiovascular risk reduction, kidney disease and obstructive sleep apnoea.

European regulator had already identified a semaglutide association

The FDA’s decision follows an earlier review by the European Medicines Agency (EMA). In June 2025, the EMA’s Pharmacovigilance Risk Assessment Committee concluded that NAION should be listed as a very rare side effect of semaglutide medicines, including Ozempic, Rybelsus and Wegovy.

The EMA estimated that the condition could affect up to one in 10,000 people taking semaglutide. Its review found that epidemiological studies suggested an approximately two-fold increase in risk among adults with type 2 diabetes compared with people not taking the medicine.

The European assessment was specific to semaglutide, while the FDA’s November 2026 action extends labelling requirements across the GLP-1 receptor agonist class.

What the warning means for pharmaceutical companies

The FDA requirement adds another safety communication and labelling obligation for companies operating in the GLP-1 market. Manufacturers will need to reflect the regulator’s warning in product information and ensure that healthcare professionals and patients are informed about the potential symptoms.

The agency advises patients to contact a healthcare professional immediately if they experience sudden, painless vision loss, blind spots, tunnel vision, colour distortion or other sudden visual disturbances in one eye. Healthcare professionals are advised to assess suspected cases promptly and consider discontinuing the medicine if NAION develops, unless the treatment benefits clearly outweigh the risk.

The warning does not amount to a withdrawal or suspension of the medicines. It also does not establish that every patient taking a GLP-1 medicine faces a substantial risk of vision loss. The FDA’s trial analysis indicates that reported events were rare, while its real-world findings varied according to the comparison treatment.

For Novo Nordisk, Eli Lilly and other manufacturers, the development highlights the importance of continued safety monitoring as GLP-1 medicines reach larger patient populations and gain additional approved uses. Further evidence will be important in clarifying the relationship between these treatments and NAION, including the extent to which underlying conditions such as diabetes, high blood pressure and sleep apnoea contribute to the observed risk.

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