Popular weight loss drugs including Ozempic and Wegovy will carry a new warning about a possible rare side effect that can sometimes lead to permanent vision loss, U.S. health regulators announced Monday.

The Food and Drug Administration said the risk will be added to the labeling of all GLP-1 drugs, the blockbuster medications used to treat obesity, diabetes and several other medical conditions. The class includes a dozen injectable or pill-based drugs, including widely used brands like Zepbound and Mounjaro.

The eye condition, known as non-arteritic anterior ischemic optic neuropathy, can cause significant vision loss. The problem, which has been reported with all GLP-1 drugs, is caused by decreased blood flow to the optic nerve, although the underlying cause isn’t understood, the FDA said.