The Food and Drug Administration is warning that popular obesity drugs—including Ozempic, Wegovy, Zepbound, and Mounjaro—may carry a “potential increased risk” of a rare eye condition that can lead to permanent vision loss.

In a drug safety communication Monday , the FDA said it will now require makers of GLP-1 receptor agonist drugs to add a warning about that risk on their drug labels. The specific eye condition it warns of is called non-arteritic anterior ischemic optic neuropathy or NAION . The condition is caused by restricted blood flow to the optic nerve, which leads to swelling and cell death and ultimately damages the nerve, causing abrupt vision loss that can often be permanent.

It’s unknown how GLP-1 drugs may cause NAION. The condition is rare overall, occurring in somewhere between two and 10 people in 100,000 in the general population, according to the American Academy of Ophthalmology. These small numbers have made it more difficult to determine with certainty if there is a connection.…