What NAION means
Non-arteritic anterior ischaemic optic neuropathy affects the blood supply to the optic nerve. NAION causes sudden, often painless loss of vision, sometimes partial and usually in one eye at a time. You may notice a shadow, a missing area or a sudden blur instead of complete blindness.
The MHRA's February 2026 communication describes the link with semaglutide as very rare, affecting up to one in 10,000 people taking the medicine. The figure gives a small overall frequency. The figure cannot predict your own risk, and most changes in vision have other causes.
Act on symptoms straight away
Go to eye casualty where available, or A&E, urgently for sudden loss of vision or rapidly worsening sight. Do not wait for a routine optician appointment, your next injection review or a reply from an online pharmacy. Tell the team you take semaglutide and give the product, dose and date of your last dose.
Several urgent problems change vision, including retinal and blood vessel conditions. No website can tell them apart reliably. A rare medicine reaction is no reason to delay assessment once you have symptoms.
What happens to your treatment
An ophthalmologist assesses whether you have NAION or another eye condition. UK product information says to stop semaglutide if NAION is confirmed. Agree the medicine decision with your clinicians. Switching to another semaglutide brand gives you the same active substance.
If you have no symptoms, a headline about a rare risk is no reason to drop prescribed treatment suddenly. Talk through your concerns in light of your own eye history, heart risk, diabetes and the benefits of treatment. An individual assessment tells you more than a risk figure applied to everyone.
Diabetic retinopathy is a separate condition
Diabetic retinopathy damages the retina through changes caused by diabetes. A fast improvement in glucose control can briefly worsen existing retinopathy in some cases. If you have known retinopathy, especially if you use insulin, discuss monitoring with your diabetes and eye teams before and during semaglutide treatment.
Keep going to diabetic eye screening and any specialist follow-up. Routine screening does not replace urgent assessment of sudden symptoms. A recent reassuring eye test does not guarantee a new problem is harmless.
Reading safety reports
Spontaneous side-effect reports help spot warning signals. On their own they cannot give a reliable rate or compare the safety of different doses. Reporting patterns, underlying illness and the number of people exposed all distort simple comparisons.
Be wary of claims that tablets, lower doses or another brand remove the risk unless sound evidence and regulator guidance back them. After you get care, report a suspected reaction through Yellow Card. Make sure the clinical diagnosis follows you into future prescribing decisions, so a serious eye event is not recorded as vague blurred vision.
Sources
Your own medicine leaflet and prescriber come first. A source from another country does not mean the same rule applies in the UK.
- Wegovy FlexTouch UK prescribing information medicines.org.uk
- MHRA: semaglutide and NAION gov.uk
- NHS: diabetic retinopathy nhs.uk
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