Semaglutide and NAION vision loss: what EMA, MHRA, the FDA and the studies report

Editorial team. Sources are cited below. This article is informational and is not medical advice; it was not reviewed by a named clinician.

Most GLP-1 safety coverage centers on the stomach, gallbladder and pancreas. A newer question concerns the optic nerve. This article explains what NAION is, what European and UK regulators concluded, how the US situation differs, what the main studies found, and what to do if your vision changes. It cannot tell you whether the medicine is right for you; that decision belongs with your prescriber.

What NAION is

The UK medicines regulator describes NAION as an extremely rare event caused by reduced blood flow to the front of the optic nerve. It usually causes sudden, painless vision loss in one eye, which patients may describe as blurring or cloudiness (MHRA press release, 5 February 2026). NAION is different from diabetic retinopathy, which is damage to retinal blood vessels and is already a labeled warning; see our article on GLP-1 medicines and diabetic retinopathy.

What European and UK regulators concluded

• EMA, June 2025. The European Medicines Agency’s safety committee (PRAC) concluded that NAION is a side effect of semaglutide, affecting Ozempic, Rybelsus and Wegovy. It classed the effect as “very rare,” meaning up to 1 in 10,000 people taking semaglutide. EMA said large studies in adults with type 2 diabetes found about a twofold increased risk compared with people not taking the medicine, equating to roughly one additional case per 10,000 person-years of treatment. Treatment should be stopped if NAION is confirmed (EMA news item).
• MHRA, February 2026. The UK regulator updated product information for Ozempic, Rybelsus and Wegovy and said the risk “may affect up to 1 in 10,000 people taking semaglutide.” It reported three spontaneous Yellow Card reports of NAION with semaglutide from 2018 to 1 August 2025, against roughly 10.2 million packs dispensed in the past five years, and said it was still reviewing evidence on other GLP-1 medicines (MHRA).

What the FDA has said

The FDA publishes quarterly lists of potential safety signals drawn from its adverse event reporting system. The October to December 2024 list includes NAION for the GLP-1 receptor agonist class, naming Ozempic, Rybelsus, Wegovy, Mounjaro and Zepbound among many products, with the status “FDA is evaluating the need for regulatory action.” The page states information as of March 6, 2025 (FDA potential signals list). A signal listing is an item under evaluation, not a finding that the medicines cause the event. We did not find a later FDA conclusion on NAION.

We read the current prescribing information for each major product and looked for optic neuropathy wording in the warnings and postmarketing sections. We found none in these labels:

• Wegovy (revised 06/2026)
• Ozempic (revised 05/2026)
• Zepbound (revised 08/2026)
• Mounjaro (revised 08/2026)

Our check of the Wegovy file covered only part of the document because the text was truncated, so treat that one as the least complete. The labels do carry a separate diabetic retinopathy warning. Labels change, so check the current version on DailyMed.

What the studies found

All of the studies below are observational. They can show an association but cannot prove the medicine caused the event.

Study	Population and design	Reported result
Hathaway et al., JAMA Ophthalmology 2024	Single academic neuro-ophthalmology center, 16,827 patients; matched cohorts with type 2 diabetes (194 semaglutide, 516 comparator) and with overweight or obesity (361 semaglutide, 618 comparator)	36-month NAION incidence 8.9% vs 1.8% in type 2 diabetes (HR 4.28, 95% CI 1.62-11.29) and 6.7% vs 0.8% in overweight or obesity (HR 7.64, 95% CI 2.21-26.36). Event counts were small (for example 6 comparator events in the diabetes group).
OHDSI multi-database study, JAMA Ophthalmology 2025	14 databases; 37.1 million people with type 2 diabetes, including 810,390 new semaglutide users	Incidence 14.5 per 100,000 person-years on semaglutide. Cohort HRs of 1.23 to 1.44 versus three comparators were not statistically significant; with a stricter NAION definition versus empagliflozin the HR was 2.27 (95% CI 1.16-4.46). Self-controlled analysis IRR 1.32 (95% CI 1.14-1.54). Authors called the increase modest and smaller than previously reported.
TriNetX study, JAMA Network Open	US electronic records; 159,398 matched adults with type 2 diabetes; semaglutide or tirzepatide vs other antidiabetic drugs; 2-year follow-up	NAION in 35 patients (0.04%) vs 19 (0.02%); HR 1.76 (95% CI 1.01-3.07). The authors stated that absolute risk remained low.
US Veterans study, JAMA Ophthalmology	102,361 veterans with type 2 diabetes; 11,478 semaglutide vs 90,883 SGLT2 inhibitor initiators	123 vs 67 NAION cases per 100,000 person-years; HR 2.33 (95% CI 1.54-3.54); risk difference 0.16 percentage points. Authors recommend counseling on this rare but serious event.

Taken together, these studies lean toward a relative increase in risk for semaglutide, with estimates that vary widely between studies. The size of the effect differs by study design and comparator group, and the single-center study has the widest uncertainty. The studies above mostly involve adults with type 2 diabetes; evidence in people using these medicines only for weight loss is thinner, and the evidence for tirzepatide is much more limited than for semaglutide.

What to do

• Know the symptom. Sudden blurring, cloudiness or loss of vision, usually in one eye and often painless. EMA advises contacting a doctor without delay for sudden vision loss or rapidly worsening eyesight, and the MHRA advises urgent attendance at an eye casualty department or emergency department.
• Do not wait it out. Do not stop prescribed medicine on your own before speaking to a clinician, but do not delay seeking care for new vision loss.
• Tell your clinicians about your history. Tell your prescriber and eye doctor if you have had optic nerve problems or vision loss in the past. Keep routine dilated eye exams if you have diabetes.
• Report suspected reactions through the FDA MedWatch program.

Common questions

Does the US label warn about NAION?

Not in the Wegovy, Ozempic, Zepbound or Mounjaro labels we checked. The FDA has listed it as a potential signal and has said it was evaluating regulatory action.

Is this a reason to avoid semaglutide?

The regulators that added the warning describe the risk as very rare. Whether the benefits outweigh a rare risk depends on your health, so it is a conversation for you and your prescriber.

Does this apply to compounded semaglutide?

The studies concerned semaglutide medicines generally. Compounded products do not have an FDA-approved label; see our article on compounded semaglutide versus Wegovy.

For a broader comparison of the two main drugs, see tirzepatide vs. semaglutide.

Medical disclaimer. This article is informational and is not medical advice. It does not replace an eye examination or a conversation with your prescriber. Sudden vision loss is an emergency: seek care right away. Do not start, stop or change a prescribed medicine without instructions from your prescriber.

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