The Food and Drug Administration said Monday that GLP-1 drugmakers must add a warning label about a rare eye disease that can cause sudden blindness.
The condition, called nonarteritic anterior ischemic optic neuropathy, or NAION, affects the optic nerve, which transmits signals from the eye to the brain. When blood flow to the nerve is reduced or blocked, it can lead to sudden loss of vision. The condition is permanent with no known treatment.
The FDA said “there is a potential increased risk of rare NAION” in people taking GLP-1 medications.
The agency’s requirement applies to all GLP-1s, including Novo Nordisk’s Ozempic and Wegovy and Eli Lilly’s Mounjaro and Zepbound, as well as several older GLP-1 diabetes drugs.
Spokespeople for Novo Nordisk and Eli Lilly said patient safety is their top priority.
Previous research has shown that GLP-1 use may increase the risk of NAION, and Lilly said she is aware of studies on this potential link.
The FDA said it began investigating a possible link after the release of a 2024 study. in JAMA Ophthalmology, which found that diabetic patients prescribed semaglutide were four times more likely to develop NAION than those who did not receive the drug.
The agency said it reviewed side effect reports submitted to its adverse event monitoring system and analyzed data from several clinical trials. Cases of NAION have been reported for all currently marketed GLP-1 drugs, the FDA found. However, FDA scientists have not been able to identify a mechanism by which the drugs might increase the risk of eye disease.
Risk factors for NAION may overlap with conditions seen in people taking GLP-1 medications, including type 2 diabetes, sleep apnea, and hypertension.
NAION is the second most common optic nerve disease in the United States, affecting up to 10 in 100,000 people over age 50, according to the American Academy of Ophthalmology.
“Patients and caregivers should be aware of a potential increased risk of NAION, a rare disease that can cause an acute, painless decrease in vision in one eye, including permanent vision loss,” with the use of GLP-1, the FDA said in the release.
Drug labels from Novo Nordisk and Lilly also have other warnings, including about pancreatitis, gallbladder problems and kidney damage.
The labels also carry a black box warning – the FDA’s strongest safety warning – regarding a possible risk of thyroid tumors.
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