EMA concludes NAION is a very rare side effect of semaglutide

The European Medicines Agency's safety committee has concluded that non-arteritic anterior ischemic optic neuropathy (NAION), an eye condition that can cause vision loss, is a "very rare" side effect of semaglutide, the active ingredient in Ozempic, Rybelsus and Wegovy ^[1]. The agency recommended that the product information for those medicines be updated, and said treatment should be stopped if NAION is confirmed ^[1].

The conclusion came from the Pharmacovigilance Risk Assessment Committee (PRAC), which announced its findings on 6 June 2025 ^[1]. EMA revised the announcement on 13 June 2025 to delete a reference to the European Commission issuing a legally binding decision on the procedure ^[1].

What the review found

PRAC reviewed non-clinical studies, clinical trials, post-marketing surveillance and published medical literature before reaching its conclusion ^[1]. It classified NAION as "very rare," a European labeling term meaning it may affect up to 1 in 10,000 people taking the medicine ^[1].

The numbers behind that classification: several large epidemiological studies suggest that semaglutide exposure in adults with type 2 diabetes is linked to roughly a two-fold increase in the risk of developing NAION compared with people not taking the drug ^[1]. EMA said that translates to about one additional case of NAION per 10,000 person-years of treatment — one person-year meaning one person taking semaglutide for one year ^[1]. Data from clinical trials also pointed to a slightly higher risk compared with placebo ^[1].

EMA's practical advice was direct: patients who experience sudden loss of vision or rapidly worsening eyesight during treatment should contact their doctor without delay, and if NAION is confirmed, semaglutide should be stopped ^[1].

What NAION is

The World Health Organization, which issued its own alert to health care professionals and regulators on 27 June 2025, described NAION as a leading cause of vision loss in adults and the second most common optic neuropathy after glaucoma ^[2]. It typically shows up as sudden, painless vision loss in one eye, along with swelling of the optic disc ^[2]. According to WHO, the vision loss is generally irreversible and there is currently no effective treatment ^[2].

WHO said it issued the alert because of how widely semaglutide is used worldwide and because of the serious nature of NAION ^[2]. It has also received individual case safety reports of NAION after semaglutide use from multiple countries through VigiBase, its global database of reported adverse events ^[2]. Separately, at its May 2025 meeting, the WHO Advisory Committee on Safety of Medicinal Products concluded that the Risk Management Plan for semaglutide should be revised to include NAION as a potential risk, along with any additional pharmacovigilance activities required ^[2].

Why it matters for patients

For people in the US taking or considering semaglutide, the main takeaway is about scale. EMA's own figure — roughly one extra case per 10,000 person-years — describes a risk that is small in absolute terms, even though the relative increase is about two-fold ^[1]. Regulators did not recommend pulling any semaglutide product from the market or restricting who can start it; the recommendation was a labeling update plus guidance to stop the drug if NAION is confirmed ^[1].

The condition's characteristics are what make it worth knowing about. Because NAION usually causes sudden, painless vision loss in one eye and is generally irreversible with no effective treatment available, the window for a medical evaluation is short ^[2]. EMA's advice frames sudden vision changes as a reason to reach a doctor without delay rather than wait ^[1].

It is also worth noting what these sources do not say. The two-fold risk estimate from epidemiological studies came specifically from adults with type 2 diabetes ^[1]; the sources do not break out risk estimates for people using semaglutide for obesity alone. The sources also do not identify which patients are more or less likely to develop NAION, and they do not address whether other GLP-1 medicines such as tirzepatide (Mounjaro, Zepbound) carry a similar signal.

What happens next

EMA said the PRAC recommendations would be sent to the Committee for Medicinal Products for Human Use (CHMP), which is responsible for questions concerning human medicines and which adopts the agency's opinion ^[1]. The sources do not give a date for that step or for when updated European labels will reach pharmacies.

The EMA and WHO actions apply to European and global regulatory processes. These sources do not state what, if anything, the US Food and Drug Administration has decided about US labeling for Ozempic, Rybelsus or Wegovy, so the American labeling status is not known from this material.