WASHINGTON, D.C. — The U.S. Food and Drug Administration has issued a new safety warning for GLP-1 medications used to treat type 2 diabetes and manage weight, requiring manufacturers to add information about a potential increased risk of a rare eye condition that can cause sudden vision loss.

The November 9 announcement concerns nonarteritic anterior ischemic optic neuropathy, or NAION, which occurs when blood flow to the front portion of the optic nerve decreases. It can cause sudden, painless deterioration in vision, usually in one eye, and may result in permanent vision loss.

Labeling changes cover diabetes and weight-loss drugs, including Ozempic, Wegovy, Mounjaro and Zepbound

The FDA described a potential increased risk associated with these medications. The condition remains rare, and the warning does not mean that patients taking the drugs will experience vision loss.

The agency’s decision followed a review of clinical trials, patient data and published studies. One analysis included 126 clinical trials involving more than 134,000 participants.

Researchers identified 6.4 NAION cases per 100,000 patient-years among people receiving GLP-1 medications, compared with 3.8 cases among those receiving other treatments or a placebo. A patient-year represents one person followed for one year.

The FDA is requiring information about the potential risk to be added to the warnings and precautions section of prescribing information for all medications covered by the action.

The drugs include Novo Nordisk’s Ozempic and Wegovy, which contain semaglutide, and Eli Lilly’s Mounjaro and Zepbound, which contain tirzepatide.

Novo Nordisk said it continues to believe that available data do not establish a causal relationship between its medications and NAION, expressing confidence in their overall balance of benefits and risks.

Diabetes itself is a recognized risk factor for NAION, complicating efforts to determine whether reported cases are associated with medication use or patients’ underlying health conditions.

The U.S. action follows earlier warnings in Europe and Britain.

In June 2025, the European Medicines Agency’s safety committee concluded that NAION is a very rare side effect of semaglutide medications, potentially affecting up to one in 10,000 users. It recommended updating product information for Ozempic, Wegovy and Rybelsus.

Britain’s Medicines and Healthcare products Regulatory Agency issued a similar warning in February 2026.

Those European and British actions focused on semaglutide-containing medications, while the new FDA action extends across the GLP-1 medications covered by its announcement.

Patients should seek urgent medical evaluation if they experience sudden vision loss or rapidly worsening eyesight. Decisions about stopping or continuing treatment should be made with their health care professional.