People who use semaglutide, the active ingredient in diabetes and weight-loss medications like Ozempic, face twice the risk of developing a serious eye condition that can lead to blindness, according to two new studies. However, the overall risk of developing the condition still remains low.
The research, out of the University of Southern Denmark, builds on work from the U.S. published in July 2024, that linked semaglutide and a condition that causes loss of blood flow to the main nerve connecting the eye to the brain. The condition, called non-arteritic anterior ischemic optic neuropathy (NAION), can result in blindness. Risk factors for NAION include diabetes, high blood pressure, and high cholesterol.
“This is a serious but very rare side effect,” Anton Pottegård, an OSD expert on medicine use and author of one of the Danish studies, said in a press release. “Often, we only learn about this kind of thing after a new drug has been on the market for a few years, as is the case with Ozempic. It should be emphasized that it is neither more serious nor more common than the rare side effects of many other medicines that we continue to use.”
Learning About Semaglutide Side Effects
A Boston-based group of researchers first pointed out the possible link between semaglutide and NAION in the July study published in JAMA Ophthalmology. The two Danish studies validate the link by drawing on a much larger pool of patients, and by analyzing patient data with two separate methods. One tapped into five years of health records of 424,152 Danes with type 2 diabetes. Of that group, 106,454 were treated with semaglutide — 67 of whom developed NAION within about 22 months after starting the medication.
The other Danish study (which has not yet been officially published), compared new semaglutide users from Denmark and Norway with those starting alternative treatments. They also found a potentially higher risk.
The numbers from both Danish studies back up a more general link between semaglutide and NAION. The country saw its average of new NAION cases rise from 67.6 cases to 148 cases a year since Ozempic’s introduction in 2018.
Read More: Beyond Weight Loss and Diabetes, Ozempic Could Help Certain Heart Conditions
Weighing the Risks
The new information doesn’t mean that patients should discontinue semaglutide use — especially for type 2 diabetes. But it does suggest first weighing the risk.
“It is extremely important that type 2 diabetes is treated, but you have to consider whether the small increased risk of severe vision loss by using Ozempic means that you should instead use one of the other new drugs that protect against kidney and cardiovascular disease,” Kurt Højlund, who researches diabetes at SDU, said in the news release.
Doctors treating patients with the medication should monitor for signs of NAION. If they see any, the patient should stop using semaglutide immediately.
Read More: Weight-Loss Drugs Like Ozempic May Be Linked to Stomach Paralysis and Other Issues
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
Brigham and Women's Hospital. Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION)
JAMA Ophthalmology. Risk of Nonarteritic Anterior Ischemic Optic Neuropathy in Patients Prescribed Semaglutide
International Journal of Retina and Vitreous. Once-weekly semaglutide doubles the five-year risk of nonarteritic anterior ischemic optic neuropathy in a Danish cohort of 424,152 persons with type 2 diabetes
Before joining Discover Magazine, Paul Smaglik spent over 20 years as a science journalist, specializing in U.S. life science policy and global scientific career issues. He began his career in newspapers, but switched to scientific magazines. His work has appeared in publications including Science News, Science, Nature, and Scientific American.
