US FDA orders blindness warning on Ozempic and other GLP-1 drugs

The US Food and Drug Administration has ordered the makers of four widely prescribed GLP-1 medicines to add warning labels about a rare eye condition that can cause sudden, permanent blindness.

The labels for Ozempic, Wegovy, Mounjaro and Zepbound must warn about nonarteritic anterior ischemic optic neuropathy, or NAION. The disorder occurs when the vessels supplying blood to the optic nerves become blocked, depriving the nerves of oxygen. It can cause painless loss of vision in one eye, the FDA said.

The agency said it had reviewed reports of NAION among people taking GLP-1 drugs, along with other studies, and concluded there is an "increased risk of rare NAION events" in users. It said it did not know why those taking the drugs may be more at risk, and that some research was hard to assess because people treated for obesity and type 2 diabetes may already carry risk factors for the condition independent of the medicine.

Novo Nordisk, which makes Wegovy, said it believed the data "do not establish a cause-and-effect relationship". The company said NAION "can have a profound impact on patients and their families" and that patient safety was a top priority, adding that it continues to monitor the safety of its medicines.

The American Academy of Ophthalmology told the BBC that "any added risk appears small, and it has not been established that these medications cause NAION". The academy said GLP-1 drugs offer important benefits for people with diabetes, obesity and heart disease, and advised patients not to stop taking them without speaking to a doctor. It said anyone who notices sudden, painless vision loss in one eye should see an ophthalmologist promptly.

There is no known treatment to reverse the vision loss caused by NAION, which the academy describes as the most common cause of acute optic nerve injury in people over 50.

Last year a safety arm of the European Medicines Agency, the EU regulator, said up to 1 in 10,000 people taking semaglutide, a key ingredient in several of the drugs, may be affected by NAION.

US researchers who analysed 17,000 patients found that those taking semaglutide were four times as likely to be diagnosed with NAION as those who were not. One of the authors, Harvard Medical School ophthalmology professor Joseph Rizzo, called the findings "significant but tentative" and said more research was needed in a more diverse population.

GLP-1 drugs already carry warnings for pancreatitis and gallbladder disease. Common side effects of semaglutide include nausea, vomiting and stomach pain.