EU Regulator Links Novo Nordisk's Ozempic to Rare Eye Disorder Risk

In a significant health advisory, the European Medicines Agency (EMA) has confirmed a link between Novo Nordisk's popular diabetes and weight-loss medications, Ozempic and Wegovy, and a rare but serious eye disorder known as non-arteritic anterior ischemic optic neuropathy (NAION). This announcement, made on June 6, 2025, marks the first official recognition by a regulatory body of this potential side effect, which may affect up to one in 10,000 patients who have been prescribed semaglutide—the active ingredient in these medications—for at least one year.

NAION is the second-most common cause of blindness resulting from optic nerve damage, trailing only glaucoma. The condition can lead to significant vision impairment and has raised concerns within the medical community. According to Dr. Sarah Johnson, Professor of Ophthalmology at the University of London and an expert in optic nerve disorders, "The confirmation of this side effect will necessitate closer monitoring of patients on these medications, particularly those with pre-existing risk factors for optic nerve damage."

The EMA's review, which commenced in December, revealed that several large-scale studies had suggested a twofold increase in the risk of developing NAION among Type 2 diabetes patients treated with Ozempic compared to those on alternative therapies. A March 2025 study involving nearly 350,000 diabetes patients indicated that the risk of developing NAION more than doubled after two years of treatment with Ozempic.

In response to these findings, the EMA has directed Novo Nordisk to update the product information for semaglutide, indicating NAION as a side effect of very rare frequency. Despite this development, Novo Nordisk maintains that the overall benefit-risk profile of semaglutide remains favorable. The company stated, "Clinical trials and extensive post-marketing studies have not demonstrated a reasonable possibility that these drugs cause NAION."

Industry analysts, such as Emily Field from Barclays, note that the clinical community has been aware of this potential risk for some time, suggesting that the announcement may not significantly alter prescribing practices. Field remarked, "I don’t see this as making any major difference to prescribing patterns, as physicians are generally informed about the risks associated with these medications."

Novo Nordisk's stock saw a modest uptick of approximately 2.5% in early trading following the EMA's announcement, indicating that investor sentiment remains cautiously optimistic despite the newly confirmed risk. This comes at a time when Novo is facing increasing pressure in the competitive obesity treatment market, particularly from Eli Lilly’s Zepbound, which, alongside Wegovy, is part of a burgeoning market projected to reach a value of around $150 billion by the end of the decade.

The implications of the EMA's findings extend beyond patient safety to the broader economic landscape of diabetes and obesity treatment. As healthcare providers navigate the complexities of prescribing these medications, patient education concerning the risks associated with NAION will become increasingly critical.

The United States Food and Drug Administration (FDA) has yet to respond to inquiries regarding whether it is conducting an investigation into this side effect. Meanwhile, healthcare professionals continue to emphasize the importance of ongoing vigilance and patient communication in the management of medications associated with potential serious adverse effects.

As Novo Nordisk works to update its product information and communicate risks to healthcare providers and patients, the situation underscores the need for continuous monitoring and transparency in the pharmaceutical industry as new data emerges regarding the safety of widely used medications.