Ozempic, Zepbound and other GLP-1 drugs will carry a warning about a rare vision loss condition. An expert puts the risk in perspective.

GLP-1 medications may slightly increase the risk of a rare eye condition that can lead to permanent vision loss, the U.S. Food and Drug Administration (FDA) announced on Nov. 9, 2026. The agency will now require GLP-1 drugs  — including Ozempic, Zepbound and 10 others —  to carry a warning about the potential risk of vision loss on their labels. 

The condition, called non-arteritic anterior ischemic optic neuropathy, or NAION, is extremely uncommon, regardless of GLP-1 use. But clinical trials suggest that there’s enough increased risk to merit a warning. 

It doesn’t mean that anyone taking a GLP-1 should stop — the chances of developing NAION are still very low, an expert tells Yahoo. But it is worth knowing what NAION is, who’s at greatest risk and the signs to watch out for. 

What is NAION? 

NAION is the most common type of ischemic optic neuropathy, a condition in which reduced blood flow damages the optic nerve, the primary pathway responsible for vision. Without enough oxygen-rich blood, parts of the nerve start to die, which can lead to permanent vision loss. 

It’s exceedingly rare, affecting roughly 2 to 10 out of every 100,000 adults ages 50 or older in the U.S. each year, according to the American Academy of Ophthalmology (AAO). It’s even less likely among younger people, who make up between 6% and 23% of U.S. cases.

NAION primarily develops in one eye. It’s usually painless, but it comes on suddenly — typically in a matter of minutes or hours, Chintan Dave, an associate professor of pharmacy and epidemiology at the Institute for Health and the Ernest Mario School of Pharmacy at Rutgers University, tells Yahoo. 

While someone’s vision may never return to its former state, the condition rarely causes blindness. Instead, “you just get blind spots, so you lose a part of your vision; it can often be in the upper or lower half of the visual field” of one eye, explains Dave. 

It’s not clear what exactly causes NAION, regardless of whether someone has taken GLP-1 medications, says Dave, who has studied the relationship between the eye condition and the medications. But there are some known risk factors, many of which overlap with health conditions that GLP-1 drugs can help to manage. They include: 

Men, he notes, are also more likely than women to develop NAION. 

There are no known treatments for NAION. But, because underlying health problems — including high blood pressure and type 2 diabetes — that can lead to NAION pose additional risks, it’s important to seek medical attention anyway, says Dave. About 15% of people who have NAION in one eye eventually develop it in the other, according to the Cleveland Clinic.

Because the condition is so uncommon, there’s little data on how likely it is to resolve or worsen, Dave says. The AAO estimates that after the onset of NAION, about 70% of people will see no further changes to their vision; 20% may experience modest improvements, and the blind spots worsen for about 10% of patients. 

How much do GLP-1 drugs raise the risk?

Dave and his colleagues found that there were between 3 and 4 more cases of NAION per 10,000 people taking GLP-1 medications than among those taking other diabetes medications over an 18-month period. 

In its own analysis, the FDA found that there were 6.4 cases of NAION among every 100,000 people taking GLP-1 drugs annually, compared with 3.8 cases per year among people taking placebos or other blood sugar medications.

What is it about GLP-1 treatments that might increase the likelihood of this vision loss condition? “NAION is so rare to begin with that we just don’t have a really good sense of what could be the reason,” says Dave. One theory, he says, is that rapid reductions in blood sugar levels may have some knock-on effect on smaller blood vessels like those that supply the optic nerve. But for now it’s nothing more than a hypothesis. 

What are the warning signs?

Some people notice slight, temporary blurring of their vision before developing NAION, according to the AAO and Cleveland Clinic. Dave says that it’s common for people with the condition to simply wake up and notice their vision is blurry. In either case, “immediately go to the emergency room,” says Dave.

Even though there is no treatment, he says doctors may be able to help prevent NAION from worsening by reducing inflammation and addressing risk factors. Seeing a doctor is also important for ruling out other causes, per the AAO. 

Dave stresses how unlikely it is to develop NAION, both in the general population and among GLP-1 users. Despite that, hundreds of patients have filed lawsuits against GLP-1 makers, claiming they developed the condition after taking the medications.

“The most important thing is to put the risk into perspective,” he says. “GLPs have substantial real-world benefits in patients with diabetes, obesity or cardiovascular disease.” While Dave’s research found an increased risk of a potentially serious eye condition, “the absolute risk was very small,” he says. “For most patients, the benefits of these medications will continue to far outweigh the risk.”