The weight-management drug Wegovy has become widely used and now comes in a convenient pill form — but recently, a study flagged that the popular medication may carry a risk of "eye stroke," also called ischemic optic neuropathy (ION), which can cause rapid vision loss.

But Wegovy users shouldn't panic, experts told Live Science. For now, the link between the drug and eye stroke is far from confirmed and the overall rate of the condition is extremely low. In the study, published in March in the British Journal of Ophthalmology, ION occurred in less than 1% of patients who reported experiencing side effects when taking Wegovy.

She added that the U.K.'s Medicines and Healthcare products Regulatory Agency — the U.K. equivalent of the Food and Drug Administration (FDA) — is informing people who use semaglutide to "seek urgent medical care if they notice their eyesight getting worse quickly."

A potential signal

This isn't the first time a connection has been drawn between weight-loss drugs and eye health concerns.

A review of the medical literature published in 2025 flagged a potential risk tied to semaglutide. In clinical trials and observational studies, the drug carried a slightly higher risk of eye stroke in those using it for diabetes management compared with non-users. That risk wasn't seen in patients using the drug for weight loss, though, and the overall rate of eye stroke in semaglutide users was still low.

The new BJO study takes this existing work and delves deeper into Wegovy, one of the most common drugs taken for chronic weight management. The findings showed a connection between Wegovy and ION, which is caused by interrupted blood flow to the optic nerve, causing damage that can lead to rapid vision loss.

"This is a very sudden and painless way to lose your eyesight," Barbara Pierscionek, deputy dean of research and innovation at Anglia Ruskin University in the U.K., told Live Science. "You can lose vision in one of your eyes or both of them. We're not quite sure exactly how it happens, but it is essentially a blockage of the blood vessels in the eye," said Pierscionek, who was not involved in the new study.

The team behind the study wanted to understand if certain weight-loss drugs presented a higher risk of ION than others. To find out, they scoured reports of side effects associated with medicines that were submitted to the U.S. FDA between December 2017 and December 2024.

They identified 31,774 reports that involved semaglutide-based drugs; of those, 3,070 were attributed to Wegovy and 20,608 to Ozempic. Twenty-eight of the Wegovy reports noted ION, compared to 47 of the Ozempic reports.

Ozempic has been on the market longer than Wegovy, having been approved in 2017 while Wegovy was approved in 2021. Factoring in this time difference, when it comes to ION, the proportional risk was higher with Wegovy than Ozempic, the study authors concluded.

A lesser-known semaglutide drug called Rybelsus, which is approved for diabetes management, had no notable association with ION in the study.

Weaknesses of the study

Importantly, the side effect reports reviewed in the study are not verified by experts. Instead, they serve to provide early hints about users' experiences with a given drug after it's been approved.

"The research did not study patients directly," Brian Woods, an ophthalmology expert at the University of Galway who wasn't involved with the study, told Live Science in an email. "Instead, it analyzed reports submitted to a large US drug safety database where suspected side effects are logged. These systems are useful for detecting possible warning signals but they cannot determine how common a complication actually is."

If a concerning pattern crops up in the database, regulators can then launch a formal investigation to see if the drug's use or approval status should be adjusted.

"The [BJO study's] findings are based on fewer than 100 reports of ION among tens of millions of entries," Woods said. "Such reports are not independently verified and lack important medical details." So while this data hints at a link between Wegovy and eye-stroke risk, more research is needed to know if the drug directly causes the condition.

"The adverse effect observed may be causal or may be because semaglutide is offered to people already at higher risk of ION, that is," Adler said. For instance, high blood pressure and cardiovascular disease are risk factors for ION, she noted. That said, diabetes is also a risk factor for ION, and Ozempic is specifically approved for people with diabetes, while Wegovy is not, though some people with diabetes may still be eligible for it. So presumably, Ozempic and Wegovy users both may be likely to have a slightly elevated risk of ION at baseline.

One difference between Wegovy and Ozempic is that the former contains a higher dose of semaglutide, but it's unclear if that affects ION risk.

"While it is biologically plausible that dose alone could be causing this, it remains unproven," Woods said. "At this stage, there is a significant likelihood that differences may be confounded by baseline risk and metabolic dynamics rather than dose alone. So, for now, the jury is still out on this key factor."

If the higher dose is relevant, that could be a concern because Wegovy just announced a higher-dose alternative of its drug.

"An increased dose would cause an increased risk, but only to those who are vulnerable," Pierscionek said. "Not everybody is at risk of ION when taking these drugs," she emphasized.