The FDA just ordered every maker of blockbuster GLP-1 weight-loss and diabetes drugs to slap a new warning on their labels: the medication may cause a rare eye condition that leads to permanent, incurable blindness. Millions of Americans are already taking these drugs.
The agency announced Monday that all currently marketed GLP-1 products — including Novo Nordisk's Ozempic and Wegovy and Eli Lilly's Mounjaro and Zepbound — must carry a warning about nonarteritic anterior ischemic optic neuropathy, or NAION. The condition strikes when blood flow to the optic nerve suddenly drops, causing painless vision loss, often in one eye. There is no proven treatment. There is no reversal. Once it hits, the damage is done.
The FDA said patients should contact a doctor immediately if they experience symptoms including sudden vision loss in one eye — which some patients first notice upon waking — blurred vision, missing patches of sight, distorted colors, or hazy spots affecting central vision, according to the New York Post.
The warning stems from a 2024 study published in JAMA Ophthalmology that found diabetes patients prescribed semaglutide — the active ingredient in Ozempic and Wegovy — were four times more likely to develop NAION than those not on the drug. The FDA acknowledged it identified "several limitations" of that study but said "further assessment of the potential increased risk for NAION was warranted."
After reviewing clinical trial data, animal studies, post-marketing reports, and its own adverse event monitoring system, the FDA found NAION cases had been reported across every GLP-1 product on the market. Still, the agency admitted it could not identify a biological mechanism explaining how the drugs might trigger the condition. FDA scientists also noted that NAION risk factors — including Type 2 diabetes, sleep apnea, and hypertension — overlap heavily with the very conditions these drugs are prescribed to treat, making the data harder to interpret.
NAION is the second most common optic nerve disease in the U.S., occurring in up to 10 out of 100,000 people over age 50, according to the American Academy of Ophthalmology, as reported by NBC News.
Spokespeople for both Novo Nordisk and Eli Lilly said patient safety is their "top priority." NBC News noted that Lilly had previously said it was aware of studies on the potential link. Neither company appears to have pushed the FDA to investigate before the 2024 study forced the issue.
This blindness warning arrives long after GLP-1s became some of the most prescribed — and most profitable — drugs in the country. The labels already carry warnings for nausea, vomiting, diarrhea, constipation, serious gallbladder problems, pancreatitis, and kidney injury. They also carry the FDA's strongest alert — a black box warning — about a possible risk of thyroid tumors. Now add incurable blindness to the list.
The FDA approved these drugs for diabetes, then for weight loss, then for reducing cardiovascular and kidney risks, then for sleep apnea and liver disease. Researchers are even investigating them for substance use disorders and neurodegenerative disease. Each new indication expands the patient pool — and the revenue. The question the agency still hasn't answered: how many Americans are now living with irreversible vision loss because the FDA waited for post-marketing disaster instead of demanding answers before approval.
