Weight Loss Drug Wegovy Shows Five Times Higher Risk of Sudden Vision Loss Than Ozempic

New research analyzing FDA adverse event reports reveals that Wegovy carries nearly five times the risk of sudden sight loss compared to Ozempic, despite both drugs containing the same active ingredient.

The Eye Stroke Connection

When three patients walked into Dr. Joseph Rizzo’s clinic at Mass Eye and Ear in late 2023, all suffering from sudden vision loss within a single week, he noticed something troubling. All three were taking semaglutide – the blockbuster ingredient found in Ozempic and Wegovy.

That observation sparked what would become the first major study linking these popular weight-loss drugs to a rare but devastating eye condition called non-arteritic anterior ischemic optic neuropathy, or NAION. Think of it as a stroke of the optic nerve – blood flow gets cut off, and vision can disappear permanently, often within hours.

Now, the latest research published in the British Journal of Ophthalmology has revealed an even more concerning pattern. Novo Nordisk’s Wegovy, the higher-dose version used for weight loss, carries nearly five times the risk of this ‘eye stroke’ compared to Ozempic, the lower-dose diabetes version.

The Numbers Tell a Stark Story

Canadian researchers combed through seven years of adverse event reports submitted to the FDA, from December 2017 to December 2024. What they found was striking: despite Ozempic generating about seven times more reports than Wegovy due to its earlier approval, Wegovy showed the strongest association with sudden vision loss.

Wegovy generated 28 reports of NAION with odds nearly 75 times higher than expected. Ozempic had 47 reports with odds about 19 times higher. The tablet form, Rybelsus, showed no increased risk at all.

The gender differences were equally eye-opening. Men taking Wegovy had 116 times greater odds of developing NAION, while women on Ozempic showed nearly 27 times greater odds. Overall, men faced more than three times the risk of women across all semaglutide formulations.

Dose Makes the Poison

The pattern emerging from multiple studies suggests a dose-dependent relationship – the higher the dose, the greater the risk. Wegovy contains up to 2.4 mg of semaglutide weekly, while Ozempic maxes out at 2 mg. Rybelsus tablets, which are poorly absorbed and work more slowly, showed no signal for vision problems.

‘The high doses of Wegovy and the fact injections were faster-acting could explain why the association was higher,’ the researchers noted. It’s a classic pharmacology principle – more drug, delivered faster, can mean more side effects.

But here’s what makes this particularly concerning: NAION typically affects about 1 in 10,000 people in the general population. While still rare among semaglutide users, the increased risk is significant enough that regulators are taking notice.

The Regulatory Response

The UK’s Medicines and Healthcare products Regulatory Agency issued a drug safety update in February 2025, warning about NAION risk. European regulators followed suit. The message is clear: while the absolute risk remains ‘extremely low,’ patients and doctors need to know what to watch for.

‘The risk of NAION in patients prescribed semaglutide is extremely low. However, as with all medicines, patients and prescribers need to be aware of the symptoms of potential side-effects,’ said Dr. Alison Cave, the MHRA’s chief safety officer.

Symptoms include sudden vision loss, usually in one eye, that’s typically painless but permanent. If it happens, patients need to see an eye specialist immediately – not next week, not tomorrow, but right now. While there’s usually no way to reverse NAION, acting within the first hour or two might help in rare cases.

Novo Nordisk has updated patient information leaflets across Europe to include NAION warnings, emphasizing that ‘patient safety is our top priority.’ The company continues working with regulators worldwide to monitor these drugs’ safety profiles.