The US Food and Drug Administration on 9 November 2026 said it will require makers of GLP-1 drugs to add warning labels about a potential increased risk of non-arteritic anterior ischemic optic neuropathy, known as NAION. The condition is a rare eye disorder that can cause sudden painless vision loss, including permanent loss in one eye.

The warning covers all GLP-1 receptor agonists, about a dozen injectable and pill-based drugs approved since 2005, including Ozempic, Wegovy and Rybelsus, which contain semaglutide, and Mounjaro and Zepbound, which contain tirzepatide. Other drugs in the class include Victoza, Saxenda and Trulicity.

What NAION is and how it shows up

NAION is caused by decreased blood flow to the front part of the optic nerve, though the underlying cause is not completely understood, the FDA said. It is a common cause of sudden, painless vision loss, and may lead to permanent impairment of sight in some cases.

The symptoms include sudden painless vision loss in one eye, often noticed on waking, along with blind spots, tunnel vision, distorted colours and hazy or blurry patches. Patients who notice such symptoms are advised to seek medical attention, and the warning will sit in the warnings and precautions section of the drug labels.

The FDA said it evaluated clinical trial data, animal data and post-marketing data, including observational studies and case reports, before ordering the label change. The review began after a July 2024 study in JAMA Ophthalmology tied semaglutide to NAION, though the FDA said that study had several limitations.

What the data showed

The FDA reviewed 126 randomised controlled trials with 134,253 patients and found 15 probable NAION cases: 10 among GLP-1 users and 5 among placebo recipients. The NAION rate was 6.4 per 100,000 patients on a GLP-1 drug, against 3.8 per 100,000 in the comparison groups.

A large study published in 2025 tracked nearly 175,000 diabetic patients treated with semaglutide and an equal number taking non-GLP-1 medications. It 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.

The European Medicines Agency said last year that NAION may affect up to 1 in 10,000 people taking semaglutide for at least a year. That was the first time a regulator had confirmed the side effect. Four patients in Denmark who experienced vision loss after using GLP-1 drugs were granted compensation, the Danish Patient Compensation body said last year.

What the drugmakers said

Novo Nordisk said it "continues to believe the data do not establish a cause-and-effect relationship" and that it remains confident in the benefit-risk profile of its GLP-1 medicines. Eli Lilly said it is "carefully evaluating the update" and will respond to the FDA promptly.

An analyst quoted in the report said the FDA action may temporarily increase patient and investor concern, but the rarity of NAION and the substantial weight, glycemic, cardiovascular, renal and sleep apnea benefits should preserve a favourable benefit-risk profile and limit changes to prescribing.

Importantly, the FDA has NOT ordered a recall and has NOT told patients to stop treatment on their own. Patients taking these medicines should speak to their doctor if they notice vision changes, rather than stopping the drug by themselves.