The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) has updated product information for healthcare professionals and patients regarding a very rare risk of Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION) associated with semaglutide.

The safety update, issued on February 5, 2026, follows evidence suggesting that semaglutide treatment may, in rare cases, be linked to NAION, an ischemic eye condition caused by reduced blood flow to the front part of the optic nerve. The condition typically presents as sudden, painless vision loss in one eye, often described by patients as blurred or cloudy vision.

Semaglutide, a Glucagon-Like Peptide-1 Receptor Agonist (GLP-1RA), is marketed as Ozempic and Rybelsus for the treatment of type 2 diabetes, and as Wegovy for weight management and cardiovascular risk reduction in overweight or obese patients.

Study suggests, NAION may affect up to 1 in 10,000 people taking semaglutide. Since the medicine was first authorised in the UK in 2018, the MHRA’s Yellow Card scheme has received three spontaneous reports suggestive of NAION linked to semaglutide, as of August 1, 2025. During the past five years, an estimated 10.2 million packs of semaglutide have been dispensed in the UK.

The MHRA has also published a Drug Safety Update to inform healthcare professionals of the potential risk. The regulator is currently reviewing available evidence to determine whether similar associations exist with other GLP-1 receptor agonists.

Dr Alison Cave, MHRA’s Chief Safety Officer, said patient safety remains the agency’s top priority and emphasised that although the potential risk is extremely small, awareness of symptoms is important.

Patients taking semaglutide who experience sudden changes in vision, including rapid deterioration in one or both eyes, are advised to seek urgent medical attention at an eye casualty department or Accident & Emergency unit. Suspected side effects can be reported through the MHRA Yellow Card scheme via its website or mobile app.

The MHRA regulates medicines and medical devices in the UK, ensuring that their benefits outweigh potential risks through ongoing safety monitoring and evidence-based evaluation.