FDA Adds Blindness Warning to GLP-1s

U.S. regulators have ordered makers of GLP-1 drugs to add a new warning about a rare eye condition that can cause sudden, permanent vision loss, widening the safety discussion around medicines that have become central to diabetes care and weight loss treatment.

The Food and Drug Administration said labels for all GLP-1 drugs should warn about nonarteritic anterior ischemic optic neuropathy, or NAION. The condition affects the optic nerve, and reduced or blocked blood flow can lead to abrupt vision loss in one eye. The agency said there is a “potential increased risk” of NAION in people taking these drugs.

The requirement applies across the class, including Novo Nordisk’s Ozempic and Wegovy, Eli Lilly’s Mounjaro and Zepbound, and older GLP-1 diabetes medicines.

What is established is narrower than the scale of public attention around these drugs. The FDA did not say GLP-1s are proven to cause NAION in every reported case, and its scientists were not able to identify a biological mechanism explaining how the drugs might raise risk. That matters, because many people prescribed GLP-1s already have conditions linked to NAION risk, including Type 2 diabetes, sleep apnea and hypertension.

Still, the agency said it reviewed adverse-event reports and data from multiple clinical trials, and found that cases of NAION had been reported for all currently marketed GLP-1 drugs. It also pointed to a 2024 study published in JAMA Ophthalmology that found diabetes patients prescribed semaglutide were four times as likely to develop NAION as those not prescribed the drug.

That leaves several practical questions unanswered, including whether risk differs across individual drugs, doses or patient groups. The label change is a regulatory warning, not a full map of who faces what level of danger.

NAION is rare. The American Academy of Ophthalmology says it occurs in up to 10 out of 100,000 people over 50 in the United States. It is also permanent, with no known treatment, which helps explain why a rare risk is still serious enough to force a label change.

Novo Nordisk and Eli Lilly said patient safety is a priority. Their GLP-1 labels already carry warnings for pancreatitis, gallbladder problems and kidney injury, as well as the FDA’s strongest boxed warning about a possible risk of thyroid tumors.