FDA Orders Eye Condition Warning on Popular Weight-Loss Drugs

People taking popular diabetes and weight-loss medicines, including Ozempic, Wegovy, Mounjaro and Zepbound, will now see additional warnings about a rare eye condition that can cause sudden and potentially permanent vision loss.

The United States Food and Drug Administration (FDA) has directed manufacturers of the medicines to include warnings about nonarteritic anterior ischemic optic neuropathy (NAION), a condition that affects the blood supply to the optic nerve.

NAION occurs when blood flow to the optic nerve is reduced, depriving it of oxygen. It can cause sudden, painless loss of vision in one eye, and the damage may be permanent.

The FDA said it reviewed reports of the condition among people using GLP-1 medicines, alongside findings from other studies, before concluding that there is an increased risk of rare NAION events among users.

However, the American Academy of Ophthalmology says the possible additional risk appears small and that a direct cause-and-effect relationship has not been established.

The organisation has urged patients not to stop taking their medication without first consulting their doctors. It also advises anyone experiencing sudden, painless vision loss in one eye to seek urgent assessment from an eye specialist.

There is currently no known treatment that can reverse vision loss caused by NAION. The condition is also the most common cause of acute optic nerve injury among people over the age of 50, according to the academy.

Novo Nordisk, the manufacturer of Wegovy, has also said available data do not establish that its medicines directly cause the condition. The company said patient safety remains a priority and that it continues to monitor the safety of its medicines.

The FDA acknowledged that assessing the possible link is complicated because some people taking GLP-1 medicines for obesity and type 2 diabetes may already have other risk factors for NAION. The reason for the possible increased risk among users remains unclear.

The medicines already carry warnings about other potential complications, including pancreatitis and gallbladder disease. Common side effects associated with semaglutide, an active ingredient in some GLP-1 medicines, include nausea, vomiting and stomach pain.

The European Medicines Agency's safety committee previously estimated that NAION could affect up to one in 10,000 people taking semaglutide.

A US study involving 17,000 patients also found that people taking semaglutide were four times more likely to receive a NAION diagnosis than those who were not taking the medicine. However, one of the study's authors, Harvard Medical School ophthalmology professor Dr Joseph Rizzo, described the findings as significant but tentative, saying further research involving more diverse populations was needed.

The latest FDA action adds another safety warning to a group of medicines widely used to manage diabetes and obesity, while highlighting the need for continued research into their possible risks.