MHRA Updates Semaglutide Guidance on NAION Risk

MHRA Guidance & Safety

Published February 5th, 2026

Detected February 6th, 2026

Summary

The MHRA has updated its guidance for semaglutide prescribers and patients regarding the very rare risk of non-arteritic anterior ischemic optic neuropathy (NAION). The update alerts healthcare professionals and patients to the symptoms and advises immediate medical attention if vision changes occur. This guidance follows three reports of NAION associated with semaglutide since 2018.

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What changed

The UK's MHRA has updated product information and guidance concerning semaglutide (Ozempic, Rybelsus, Wegovy) due to the very rare risk of non-arteritic anterior ischemic optic neuropathy (NAION). NAION is a condition causing sudden, painless vision loss in one eye. The update emphasizes that while the risk is extremely small (estimated up to 1 in 10,000), patients experiencing sudden vision changes should seek urgent medical attention and report symptoms via the Yellow Card scheme.

Healthcare providers prescribing semaglutide must be aware of this potential side effect and advise patients accordingly. Patients taking semaglutide should be vigilant for any changes in their eyesight and seek immediate care if symptoms arise. The MHRA is also reviewing evidence for similar risks with other GLP-1 agonists. This guidance aims to ensure patient safety by promoting prompt recognition and management of this rare adverse event.

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Press release

MHRA updates guidance for semaglutide prescribers and patients

MHRA updates product information regarding the very rare risk of non-arteritic anterior ischemic optic neuropathy (NAION) in patients taking semaglutide.

From: Medicines and Healthcare products Regulatory Agency Published 5 February 2026

Image of an eye.

The Medicines and Healthcare products Regulatory Agency (MHRA) has today (5 February 2026) updated product information for healthcare professionals and patients regarding the risk of the very rare occurrence of non-arteritic anterior ischemic optic neuropathy (NAION) in patients taking semaglutide.

Semaglutide is a glucagon-like peptide-1 receptor agonist (GLP-1RA) sold under the brand names Ozempic and Rybelsus, prescribed for patients with type 2 diabetes; and also as Wegovy, which is indicated for weight management and cardiovascular risk reduction in patients who are overweight or obese.

NAION is an extremely rare ischemic event which occurs due to reduced blood flow to the front portion of the optic nerve which typically causes sudden, painless vision loss in one eye. Patients who have experienced NAION describe it as a blurring or cloudiness of vision.

Patients taking semaglutide who notice a change in their eyesight, such as sudden impairment to their vision, or if their eyesight gets worse very quickly in one or both eyes, should urgently attend eye casualty (if available in the area) or A&E.

Dr Alison Cave, MHRA’s Chief Safety Officer said:

“Patient safety is the MHRA’s top priority and we continually monitor the safety and efficacy of all licensed medicines.

“While the potential risk of NAION for patients prescribed semaglutide is extremely small, it is important that patients and healthcare professionals are alert to the associated symptoms.

“If you, or someone you care for, is taking semaglutide and you notice sudden loss of vision in one eye, then we advise you to urgently attend eye casualty (if available in your area) or A&E and report it via our https://yellowcard.mhra.gov.uk/ scheme.”

Guidance on potential side effects of semaglutide and on its safe and effective use is available here.

Notes to editors

The Medicines and Healthcare products Regulatory Agency (MHRA) is responsible for regulating all medicines and medical devices in the UK by ensuring they work and are acceptably safe. All our work is underpinned by robust and fact-based judgements to ensure that the benefits justify any risks.
The MHRA is an executive agency of the Department of Health and Social Care.
We have today published a Drug Safety Update for healthcare professionals to alert them to the risk of NAION.
Studies suggest semaglutide treatment may be very rarely associated with NAION; this means it may affect up to 1 in 10,000 people taking semaglutide.
In the UK, since semaglutide’s first authorisation in 2018, up to 1st August 2025 the Yellow Card scheme has received three spontaneous reports suggestive of NAION associated with semaglutide. For context, in the past 5 years, it is estimated that roughly 10.2 million packs of semaglutide have been dispensed.
The MHRA is reviewing any evidence for an association with other GLP-1 agonists.
Suspected side effects or adverse drug reactions to any medicines should be reported to the MHRA Yellow Card scheme, either through the website (https://yellowcard.mhra.gov.uk) or by searching the Google Play or Apple App stores for MHRA Yellow Card.
For media enquiries, please contact the newscentre@mhra.gov.uk, or call on 020 3080 7651.