The short answer: Possibly, but the risk is very small. In June 2025 the European Medicines Agency concluded that NAION is a "very rare" side effect of semaglutide, affecting up to 1 in 10,000 people who take it. Several large studies found about double the usual risk in people with type 2 diabetes, while other studies found no link. The US Ozempic label does not name NAION as of its 2026 revision.
What is NAION?
NAION stands for non-arteritic anterior ischemic optic neuropathy. It is a loss of blood flow to the front of the optic nerve, the cable that carries signals from the eye to the brain.
The World Health Organization describes it as sudden, painless vision loss in one eye, with swelling of the optic disc. WHO calls it the second most common optic neuropathy after glaucoma. The vision loss is generally permanent, and no effective treatment exists.
That is why a rare event gets this much attention. Most Ozempic side effects, such as nausea, fade or can be managed. NAION usually does not reverse. Our guide to long-term Ozempic side effects covers the more common problems.
What have regulators said about Ozempic and NAION?
Europe acted first. On 6 June 2025 the EMA safety committee (PRAC) finished a review of semaglutide medicines: Ozempic, Rybelsus and Wegovy. It looked at laboratory studies, clinical trials, post-marketing reports and published research. Its conclusions:
- NAION is a very rare side effect of semaglutide, meaning it may affect up to 1 in 10,000 people taking it.
- Large population studies suggest about a two-fold higher risk in adults with type 2 diabetes who take semaglutide.
- That equals about one extra case of NAION per 10,000 person-years of treatment. One person-year is one person taking the drug for one year.
- Clinical trial data also pointed to a slightly higher risk with semaglutide than with placebo.
- European product information should list NAION, and treatment should stop if NAION is confirmed.
On 27 June 2025, WHO issued a medical product alert on the same risk. Its advisory committee said the risk management plan for semaglutide should list NAION as a potential risk. WHO also said it had received case reports from multiple countries.
Does the US Ozempic label mention NAION?
No. We read the current Ozempic prescribing information on DailyMed and the May 2026 label on the FDA site. Neither contains the term NAION or any mention of the optic nerve.
The US label does carry a separate eye warning, section 5.3, on diabetic retinopathy complications. That is damage to the retina from diabetes, a different condition from NAION. In a 2-year trial of people with type 2 diabetes and high cardiovascular risk, these complications occurred in 3.0% of patients on Ozempic and 1.8% on placebo. Among people who already had diabetic retinopathy, the rates were 8.2% and 5.2%.
The label notes that rapid improvement in glucose control has been linked to a temporary worsening of diabetic retinopathy. It says patients with a history of diabetic retinopathy should be monitored. It also tells all patients to contact their healthcare provider if they have changes in vision during treatment.
What do the studies show?
The studies disagree. All of them are observational, so none can prove that Ozempic causes NAION.
Studies that found a higher risk:
- The 2024 Harvard study in JAMA Ophthalmology started the concern. Among patients seen by neuro-ophthalmologists at one academic center, the 36-month cumulative incidence of NAION in people with type 2 diabetes was 8.9% with semaglutide and 1.8% with other diabetes drugs (hazard ratio 4.28). In people with overweight or obesity it was 6.7% versus 0.8%.
- A Danish study of 424,152 people with type 2 diabetes found 0.228 cases per 1,000 person-years with once-weekly semaglutide and 0.093 without it (hazard ratio 2.19). In total, 218 people developed NAION over five years.
- A Danish-Norwegian registry study compared semaglutide with SGLT-2 inhibitors. The pooled hazard ratio was 2.81. The extra risk was 1.41 cases per 10,000 person-years, and the authors stated that the absolute risk remains low.
- A US database study of 174,584 semaglutide users with diabetes and an equal number of comparison patients found no significant difference at one year, then a higher risk at two years (hazard ratio 2.39) through four years.
Studies that found no higher risk:
- A multinational study in Ophthalmology used records from 160 healthcare organizations in 21 countries. It found no significant link at one, two or three years in people with type 2 diabetes, obesity, or both.
- A US military health system study of 1,212,775 people found lower odds of NAION with semaglutide in type 2 diabetes (odds ratio 0.36) and no significant difference in overweight or obesity.
- A 2026 meta-analysis of six studies reported a pooled adjusted hazard ratio of 1.63, with a confidence interval of 0.88 to 2.39 that includes no effect. The estimate for type 2 diabetes alone was 1.70 and was statistically significant. The authors rated the certainty as low to very low.
How big is the risk in real numbers?
The relative risk and the absolute risk tell different stories. A doubled risk sounds large. The starting risk is tiny, so the doubled risk is still tiny.
In the Danish-Norwegian study, about 2.2 of every 10,000 Danish semaglutide users developed NAION per year, against about 1.2 of every 10,000 SGLT-2 inhibitor users. The EMA estimate is similar: about one extra case for every 10,000 people treated for a year.
The Harvard figures of 8.9% and 6.7% look far worse, but they do not describe ordinary Ozempic users. That study drew on patients referred to a neuro-ophthalmology service, a group in which optic nerve disease is far more common. The population-wide studies give the better estimate of everyday risk.
The picture is less clear for people who take semaglutide for weight alone. The EMA two-fold figure refers to adults with type 2 diabetes. In the 2026 meta-analysis, the pooled estimate for obesity or overweight was 0.47 and was not statistically significant.
What vision symptoms need urgent care?
The EMA advice is direct. If you have a sudden loss of vision or rapidly worsening eyesight during semaglutide treatment, contact your doctor without delay. Based on the WHO description, the typical pattern is:
- Sudden vision loss in one eye
- No pain with the vision loss
Sudden vision loss has other causes too, and some of them are emergencies. Get same-day medical care. Do not wait for your next routine appointment.
Blurry vision is different and more common. The US label lists blurred vision as a possible sign of low blood sugar, mainly when Ozempic is combined with insulin or a sulfonylurea. See our guide to managing Ozempic side effects.
Should you stop Ozempic because of NAION?
The EMA says semaglutide should be stopped if NAION is confirmed. It did not tell people without NAION to stop. The authors of the multinational study wrote that avoiding semaglutide only because of NAION concerns may not be warranted, given its benefits for blood glucose and cardiovascular health.
Three steps are reasonable for most people:
- Tell your prescriber about any eye disease, including diabetic retinopathy or a past NAION in either eye.
- Keep your regular eye exams if you have diabetes.
- Talk with your prescriber before you stop. Read what happens when you stop Ozempic first.
The EMA review covered semaglutide only. For the other medicines in this drug class, see glp1.md.
The bottom line
Ozempic may raise the risk of NAION, a sudden and usually permanent loss of vision in one eye. European regulators list it as a very rare side effect: up to 1 in 10,000 users, or about one extra case per 10,000 people treated for a year. The research is split, and the US label does not name NAION. Treat sudden vision loss as an emergency, and raise any eye history with your prescriber.
Last updated: October 2026. This article is for informational purposes only and does not constitute medical advice. Talk with your healthcare provider or eye doctor about your own vision risk before you start, stop, or change Ozempic.