Archive · 25 Sep 2026
GLP-1 Drugs Face Scrutiny Over Rare Vision-Loss Condition
Some medicines for diabetes and weight loss are being examined because of a rare eye problem called NAION.
NAION happens when blood flow to the optic nerve is disrupted.
It can cause sudden, painless loss of sight, usually in one eye.
European regulators say NAION is a very rare side effect of semaglutide.
Some studies found that semaglutide users may face a higher risk.
Other studies, including a Novo Nordisk trial analysis, did not find a clear increase.
This difference is why researchers, regulators and courts are still examining the issue.
Patients with sudden or quickly worsening vision are advised to seek medical help, and treatment should stop if NAION is confirmed.
The European Medicines Agency classified NAION as a very rare semaglutide side effect, potentially affecting up to one in 10,000 users.
NAION can cause sudden, painless vision loss in one eye when blood flow to the optic nerve is disrupted.
Novo Nordisk’s pooled randomized-trial analysis found three confirmed NAION cases among GLP-1 recipients versus five among inactive-treatment participants.
Observational studies have produced mixed findings, with some reporting higher NAION risk among semaglutide users and others finding no statistically significant increase.
US lawsuits involving Novo Nordisk and Eli Lilly products had 216 pending actions as of September 1, 2026, but the litigation does not establish causation.
- Who
- People using GLP-1 medicines, Novo Nordisk, Eli Lilly and Company, European regulators, researchers and plaintiffs in US litigation.
- What
- Semaglutide and other GLP-1 medicines are under scrutiny over a possible link to NAION, a rare condition that can cause sudden vision loss.
- When
- The European Medicines Agency issued its position in June 2025; 216 US litigation actions were pending as of September 1, 2026.
- Where
- The regulatory assessment applies in Europe, the litigation is consolidated in Pennsylvania, and the issue is also relevant to India’s expanding GLP-1 market.
- Why
- Clinical-trial and observational evidence has produced differing findings about whether semaglutide increases the risk of NAION.
Safety Concerns
Company and Trial Evidence
Risk of NAION
Safety Concerns
The European Medicines Agency said several large epidemiological studies suggested that adults with type 2 diabetes taking semaglutide had about twice the risk of NAION compared with people not taking it.
Company and Trial Evidence
Novo Nordisk said its pooled randomized-trial data did not show an increased incidence of NAION among semaglutide or other GLP-1 medicine recipients.
Interpreting research
Safety Concerns
Several observational studies and 2026 meta-analyses reported an association or higher risk of NAION among semaglutide users, particularly people with diabetes.
Company and Trial Evidence
Observational associations do not prove that semaglutide caused NAION; other reviews found no statistically significant overall increase, and the evidence was rated low to very low in one review.
US lawsuits
Safety Concerns
Plaintiffs allege that Novo Nordisk’s and Eli Lilly’s GLP-1 medicines caused NAION and raise issues involving product development, testing, regulatory history, promotion and labelling.
Company and Trial Evidence
The multidistrict litigation is a procedural consolidation and does not establish that the medicines caused NAION; Novo Nordisk says the overall benefit-risk profile remains favourable.
- Condition
- Non-arteritic anterior ischaemic optic neuropathy, or NAION, involves disrupted blood flow to the optic nerve and can cause sudden, painless vision loss.
- EMA assessment
- In June 2025, the European Medicines Agency classified NAION as a very rare semaglutide side effect, potentially affecting up to one in 10,000 users.
- Novo Nordisk trial analysis
- Across 96,829 participants, three confirmed NAION cases occurred among GLP-1 medicine recipients versus five among inactive-treatment participants.
- Observational evidence
- Some 2026 reviews found higher NAION risk among semaglutide users, while another review found no statistically significant overall increase and rated the evidence low to very low.
- US litigation
- Federal cases involving Novo Nordisk and Eli Lilly products were consolidated into multidistrict litigation in Pennsylvania.
- Pending actions
- The multidistrict litigation had 216 pending actions as of September 1, 2026.
- India market
- India’s GLP-1 market reached ₹2,333 crore on a moving annual total basis in August 2026; semaglutide accounted for ₹782 crore and tirzepatide for ₹1,456 crore.
