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The eye disorder non-arteritic anterior ischemic optic neuropathy (NAION) is a “very rare side effect” of the use of semaglutide medicines, a review conducted by the European Medicines Agency’s (EMA) Pharmacovigilance Risk Assessment Committee (PRAC) has concluded.
In a statement published on 6 June 2025, the PRAC said it had reviewed “all available data on NAION with semaglutide”, including non-clinical studies, clinical trials, post-marketing surveillance and medical literature.
In its review, PRAC concluded that NAION is a “very rare” side effect of semaglutide use and that it may affect up to 1 in 10,000 people who take the medicines.
NAION is caused by reduced blood flow to the optic nerve, which can lead to loss of vision in the affected eye.
Semaglutides are glucagon-like peptide-1 receptor agonists (GLP-1 RAs) used in diabetes mellitus and for weight management.
GLP-1 RAs containing semaglutide licensed for use in the UK include Ozempic (semaglutide; Novo Nordisk), Rybelsus (semaglutide; Novo Nordisk) and Wegovy (semaglutide; Novo Nordisk).
“Several large epidemiological studies suggest that exposure to semaglutide in adults with type 2 diabetes is associated with an approximately two-fold increase in the risk of developing NAION compared with people not taking the medicine,” the review said.
“This corresponds to approximately one additional case of NAION per 10,000 person-years of treatment.”
As a result of the findings, PRAC said it “therefore recommended that the product information for semaglutide medicines is updated to include NAION as a side effect with a frequency of ‘very rare’”.
The review also added that patients taking semaglutide should contact their doctor immediately if they experienced a sudden loss of vision or rapidly worsening eyesight during treatment. If NAION is confirmed, treatment with semaglutide should be stopped.
In January 2025, PRAC began its review of medicines containing semaglutide, after noting that two recent observational studies suggested an elevated risk of patients developing NAION.
However, “two other recent observational studies do not suggest an increased risk”, it said in meeting notes published at the time.
Commenting on PRAC’s recommendations, a spokesperson for Novo Nordisk said: “Based on the totality of evidence, we concluded that the data did not suggest a reasonable possibility of a causal relationship between semaglutide and NAION and that the ‘benefit-risk profile of semaglutide remains favourable’.
“Novo Nordisk will continue to collaborate with the MHRA [Medicines and Healthcare products Regulatory Agency] to discuss any UK impact.
“We recommend that any patients experiencing side effects while taking our medicines report them to their healthcare provider and in the UK, use the MHRA Yellow Card scheme.”
