MHRA Safety Update: Semaglutide and the Risk of Rare Vision Loss

Before we get into the update, are you starting more patients on semaglutide? We've made a free, print-ready poster for your waiting room or consultation room. It explains when patients should seek urgent help for sudden vision changes, along with new safety updates for 2026.

Ok let’s get into it…

Semaglutide, including Ozempic, Rybelsus, Wegovy, has been associated with non-arteritic anterior ischaemic optic neuropathy (NAION). That's sudden, painless vision loss in one eye caused by reduced blood flow to the optic nerve.

The absolute risk is very rare, up to 1 in 10,000. There have been three UK Yellow Card reports since 2018, against roughly 10.2 million packs dispensed. So we're not talking about a common side effect.

But here's the context that makes this important right now.

Two weeks after this safety update, NICE published the biggest overhaul of type 2 diabetes management in a decade. NG28 now names semaglutide as the preferred GLP-1 RA for patients with established cardiovascular disease. It also moves GLP-1s and tirzepatide much earlier in the pathway for three high-risk groups.

810,000 more patients just became eligible (read the full article here).

That means prescribing volumes are about to increase significantly and a very rare side effect at low volume becomes a more visible one at scale. The signal-to-noise ratio changes when the denominator grows.

We all need to be aware of the association between semaglutide and NAION and counsel patients to seek urgent assessment (A&E) if they notice sudden vision loss. Consider mentioning this as part of informed consent conversations, particularly for patients with pre-existing vascular risk factors for NAION (diabetes, hypertension, hyperlipidaemia; many of whom are exactly the patients now being started on semaglutide).