Recent research has highlighted a significant association between the weight-loss medication Wegovy and an elevated risk of sudden vision loss, particularly when compared to its counterpart, Ozempic. The study, published in the British Journal of Ophthalmology, reveals that individuals using Wegovy face nearly five times the risk of developing non-arteritic anterior ischemic optic neuropathy (Naion), a condition that can lead to irreversible sight impairment.
The Study’s Findings
Researchers examined adverse event reports submitted to the US Food and Drug Administration (FDA) from December 2017 to December 2024. The analysis focused on the side effects linked to semaglutide-based medications, which include Wegovy, Ozempic, and Rybelsus, as well as tirzepetide, marketed as Mounjaro.
The study’s findings indicate that Wegovy users are at a considerably higher risk of experiencing Naion compared to those taking Ozempic for type 2 diabetes. Specifically, the data revealed that men had a threefold increase in risk compared to women, underscoring a potential gender disparity in susceptibility to this adverse effect. The condition, often referred to as an “eye stroke,” occurs due to reduced blood flow to the optic nerve, resulting in sudden and often permanent vision loss.
Comparing the Medications
All three medications—Wegovy, Ozempic, and Rybelsus—contain the active ingredient semaglutide, but they differ in their dosages and delivery methods. Wegovy, which is prescribed for obesity management, has a higher dosage compared to Ozempic, which is typically used for diabetes care. The study posits that the heightened risk associated with Wegovy may stem from its faster-acting injectable formulation and higher dosage, which could lead to more pronounced physiological effects.
Conversely, Rybelsus, which is taken orally, showed no significant association with Naion. Researchers attribute this lack of correlation to the slower absorption rate of the tablets, which may prevent the rapid changes in blood flow that could trigger optic nerve complications.
Regulatory Response and Expert Opinions
In light of these findings, the UK Medicines and Healthcare products Regulatory Agency (MHRA) issued a safety update in February, warning healthcare professionals and patients about the potential risk of Naion associated with semaglutide. Dr Alison Cave, the MHRA’s chief safety officer, emphasised that while the risk remains extremely low, it is crucial for both patients and prescribers to recognise the symptoms of potential side effects to ensure timely intervention.
Healthcare professionals have expressed caution regarding the study’s conclusions. Dr Samantha Mann, a consultant ophthalmologist, noted that the research relied on reported side effects, which cannot definitively prove causation. She indicated that an increase in Naion cases has not been widely observed in clinical practice, suggesting that further investigations are necessary to ascertain the validity of the findings.
Meanwhile, a spokesperson for Novo Nordisk, the manufacturer of semaglutide products, reiterated the company’s commitment to patient safety, stating that they take adverse event reports seriously and work closely with regulatory bodies to monitor the safety of their medications. Although the EU patient leaflets have been updated to reflect the association with Naion, Novo Nordisk maintains that the overall benefit-risk profile of semaglutide remains favourable.
Why it Matters
The implications of this study are profound, as it raises essential questions about the safety of widely prescribed weight-loss medications. With obesity being a significant public health challenge, understanding the potential risks of treatments like Wegovy is critical for informed decision-making by both patients and healthcare providers. As the dialogue around medication safety continues, it is vital that ongoing research addresses these risks to safeguard patient well-being while promoting effective weight management strategies.
