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GLP-1 Drugs Face Scrutiny Over Rare Vision Condition
Some medicines used 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.
Some studies found that semaglutide users may have a higher risk of this problem.
Other studies did not find a clear increase, and the overall evidence was rated low or very low in one review.
Novo Nordisk said its clinical-trial analysis did not show more cases among people taking semaglutide.
European regulators have called NAION a very rare side effect of semaglutide and advised patients with sudden vision changes to seek medical help.
Lawsuits in the United States allege that GLP-1 medicines caused NAION, but the court process does not prove that they did.
Non-arteritic anterior ischaemic optic neuropathy can cause sudden, painless vision loss, usually in one eye.
Novo Nordisk said pooled clinical-trial data found three confirmed NAION cases among GLP-1 medicine recipients, versus five among inactive-treatment participants.
Observational studies have produced mixed findings, with some reporting higher risk for semaglutide and others finding no statistically significant increase.
The European Medicines Agency classified NAION as a very rare semaglutide side effect and recommended updated product warnings.
A US multidistrict litigation involving Novo Nordisk and Eli Lilly products had 216 pending actions as of September 1, 2026.
- Who
- People using GLP-1 medicines, Novo Nordisk, Eli Lilly, the European Medicines Agency, and plaintiffs in US litigation.
- What
- GLP-1 medicines, particularly semaglutide, are under scrutiny over a possible link to NAION, a rare condition that can cause sudden vision loss.
- Where
- The regulatory action was taken in Europe, the litigation is consolidated in Pennsylvania, and the issue is also relevant to India’s expanding GLP-1 market.
- When
- The European Medicines Agency issued its position in June 2025; 216 US cases were pending as of September 1, 2026.
- Why
- Clinical and observational studies have 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 pooled randomized clinical-trial data did not show an increased incidence of NAION among semaglutide participants and that the medicine’s overall benefit-risk profile remains favourable.
Interpretation of studies
Safety Concerns
Some observational analyses found a higher rate or association between semaglutide and NAION, including among people with diabetes.
Company and Trial Evidence
Another review found no statistically significant overall increase, rated the evidence low to very low, and a separate analysis found no statistically significant increase in randomized clinical trials.
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, promotion, regulatory history, and labeling.
Company and Trial Evidence
The US multidistrict litigation is a procedural consolidation and does not establish that the medicines caused NAION.
Key facts
- Condition
- Non-arteritic anterior ischaemic optic neuropathy (NAION), involving disrupted blood flow to the optic nerve.
- Novo clinical-trial analysis
- Three confirmed NAION cases among GLP-1 medicine recipients versus five among inactive-treatment participants, across 96,829 people.
- EMA assessment
- NAION was classified in June 2025 as a very rare side effect of semaglutide, potentially affecting up to one in 10,000 users.
- US litigation
- Federal cases involving Novo Nordisk and Eli Lilly products were consolidated into multidistrict litigation in Pennsylvania.
- Pending actions
- 216 actions were pending in the multidistrict litigation as of September 1, 2026.
- India GLP-1 market
- The 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.
Quotes
Novo Nordisk
Pharmaceutical company that manufactures semaglutide medicines
“Considering the totality of evidence from clinical trials, post-marketing reports and observational studies, alongside the generally low incidence rate of NAION, Novo Nordisk believes that the benefit-risk profile of semaglutide remains favourable.”
businesstoday.in
“Semaglutide has been studied in multiple clinical development programmes with a total exposure from post-marketing use of over 58 million patient-years.”
businesstoday.in
Sources
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