EMA declares NAION a very rare side effect of semaglutide

The European Medicines Agency's safety committee concluded on 6 June 2025 that non-arteritic anterior ischemic optic neuropathy, or NAION, is a "very rare" side effect of semaglutide, the active ingredient in Ozempic, Rybelsus and Wegovy ^[1]. The committee recommended that the product information for all three medicines be updated to list NAION, and said treatment should be stopped if the condition is confirmed ^[1].

NAION is an eye condition that can cause loss of vision. It happens when blood flow to the front of the optic nerve drops, without inflammation of the blood vessels \u2014 which is what separates it from "arteritic" causes ^[2]. It typically causes sudden, painless vision loss in one eye, often described as blurring or cloudiness ^[2].

What the data showed

EMA's Pharmacovigilance Risk Assessment Committee (PRAC) reviewed non-clinical studies, clinical trials, post-marketing surveillance reports and published medical literature before reaching its conclusion ^[1]. "Very rare" is a defined regulatory frequency category: it means the side effect may affect up to 1 in 10,000 people taking the medicine ^[1].

Several large epidemiological studies suggested that adults with type 2 diabetes taking semaglutide had roughly a two-fold increase in the risk of developing NAION compared with people not taking it ^[1]. In absolute terms, EMA said that works out to about one extra case of NAION per 10,000 person-years of treatment \u2014 one person-year meaning one person taking semaglutide for one year ^[1]. Clinical trial data also pointed to a slightly higher risk versus placebo ^[1].

The baseline risk matters for interpreting that doubling. Published estimates of how often NAION occurs vary widely: from 11.4 to 82 cases per 100,000 person-years in people with type 2 diabetes, and from about 7.73 to 11.35 per 100,000 person-years in the general population aged 40 and older ^[2]. Type 2 diabetes itself raises NAION risk, and other risk factors include smoking, high blood pressure and high cholesterol ^[2].

Regulators elsewhere reached the same conclusion

The UK's Medicines and Healthcare products Regulatory Agency issued its own Drug Safety Update on 5 February 2026, agreeing that semaglutide may be very rarely associated with NAION ^[2]. The MHRA noted that its expert advisory group found "conflicting evidence in the literature" but still agreed to update UK product information ^[2].

The UK numbers give a sense of scale. Since semaglutide was first authorized in the UK in 2018 through 1 August 2025, the Yellow Card reporting scheme received three spontaneous reports suggestive of NAION with semaglutide, against an estimated 10.2 million packs of semaglutide dispensed over the past five years ^[2]. The MHRA cautions that a report does not mean the medicine definitely caused the event, only that the reporter suspected it might have ^[2].

The European review covered semaglutide only; other GLP-1 receptor agonists were not included ^[2]. The MHRA said it is reviewing whether there is evidence of an association with other GLP-1 drugs ^[2].

Why it matters for patients

For most people, the absolute numbers here are small \u2014 roughly one extra case per 10,000 people treated for a year, on top of a background rate that is already higher in people with diabetes ^[1][2]. But NAION can cause permanent vision loss, so regulators treated it as worth naming on the label.

Both agencies framed the practical point around symptoms. EMA said patients who experience sudden loss of vision or rapidly worsening eyesight during semaglutide treatment should contact their doctor without delay, and that semaglutide should be stopped if NAION is confirmed ^[1]. The MHRA advises that patients reporting sudden vision loss, including partial loss, be urgently referred to an ophthalmologist ^[2]. It also flagged that privately prescribed semaglutide may not show up in a patient's medical record, so clinicians should ask about it directly ^[2].

What happens next

PRAC's recommendations were passed to EMA's Committee for Medicinal Products for Human Use, which adopts the agency's formal opinion ^[1]. EMA revised its 6 June 2025 announcement on 13 June 2025 to remove a reference to a European Commission legally binding decision ^[1]. In the UK, the Summary of Product Characteristics and Patient Information Leaflet for semaglutide products were expected to be updated "in the coming months" after the February 2026 notice ^[2].

What US labeling for Ozempic, Rybelsus and Wegovy says about NAION is not addressed in these sources.