Semaglutide, the small risk of blindness (NAION), gastroparesis — and the MDL in Pennsylvania

Semaglutide (the active ingredient in prescription products sold as Wegovy and Ozempic) has become a household name for weight loss. That popularity has brought attention not only to benefits, but to rare — sometimes serious — side effects and a growing wave of litigation. Below I summarize what the medical literature and regulators have reported about non-arteritic anterior ischemic optic neuropathy (NAION) and gastroparesis, and where the federal multidistrict litigation (MDL) in the Eastern District of Pennsylvania against Novo Nordisk and Eli Lilly stands as of mid-2025.

Quick takeaways

• Multiple studies have reported an association between semaglutide use and an increased risk of NAION (a sudden loss of blood flow to the optic nerve that can cause permanent vision loss). This finding prompted regulators to investigate and, in some jurisdictions, to require labeling changes.

• Gastroparesis (severely delayed stomach emptying) and other serious gastrointestinal injuries are central to many lawsuits. Plaintiffs say manufacturers failed to adequately warn about the possibility of long-term or severe GI injury. The MDL in Pennsylvania groups those cases for coordinated pretrial proceedings.

• The federal MDL is active (MDL No. 3094, presiding Judge Karen S. Marston) and, by mid-2025, included well over a thousand individual lawsuits consolidated for coordinated handling.

  
  

The NAION question — what the evidence says

• A peer-reviewed cohort analysis published in JAMA Ophthalmology (2024) found a statistically significant association between semaglutide prescriptions and higher rates of NAION compared with non-GLP-1 treatments in the studied population. The study reported notably higher hazard ratios and cumulative incidence among semaglutide users in that dataset.

• A larger population study from Denmark (published 2024) also reported increased incidence of NAION among semaglutide users, suggesting the signal has been seen across multiple datasets.

• In June 2025 the European Medicines Agency (EMA) concluded NAION should be listed as a very rare possible adverse reaction to semaglutide products (Wegovy, Ozempic, Rybelsus), which is a regulatory recognition of the signal seen in post-marketing surveillance and the literature (EMA required labeling changes). The EMA described NAION as very rare and tied to at least one year of exposure in their assessment.

  
  

What this means for patients: NAION is rare, but it is serious (can cause permanent vision loss). If you’re taking a semaglutide product and notice sudden vision changes — seek urgent medical attention. Discuss personal risk factors (cardiovascular disease, diabetes, “crowded” optic discs, prior NAION in the other eye) with the prescriber.

Gastroparesis and other GI injuries

• GLP-1 receptor agonists — including semaglutide agents — commonly cause nausea and slowed gastric emptying. Those are known, expected side effects and are mentioned in prescribing information. However, plaintiffs in many cases assert that the manufacturers did not adequately warn about progression to gastroparesis (a severe, potentially chronic paralysis of the stomach), bowel obstructions, or hospital-level GI events.

• The FDA has also warned about dosing and safety issues with compounded semaglutide products (dosing errors and overdoses reported), highlighting additional risks when patients obtain non-approved preparations.

  
  

What this means for patients: mild GI symptoms are common early on; persistent vomiting, severe or worsening abdominal pain, inability to tolerate food, long-term unintentional weight loss, or symptoms consistent with gastroparesis deserve prompt evaluation. Ask your prescriber about monitoring and whether an alternative therapy is appropriate.

The Multidistrict Litigation (MDL) — what’s consolidated and where it is now

• The federal MDL for GLP-1 receptor agonist product liability cases is MDL No. 3094 in the U.S. District Court for the Eastern District of Pennsylvania, overseen by Judge Karen S. Marston. The MDL consolidates personal injury actions alleging GI injuries, inadequate warnings, and other claims related to GLP-1 drugs (including Novo Nordisk’s Ozempic/Wegovy/Rybelsus and Eli Lilly’s GLP-1 products). The court’s MDL page describes the common factual issues and that monthly status conferences are being held.

• As of mid-2025 the MDL grew quickly — law-firm trackers and MDL monitors reported roughly 1,800–2,000+ individual cases pending in the MDL (counts varied as new filings were transferred). That pace made the GLP-1 MDL one of the faster-growing product-liability consolidations of the period. (Reported counts: ~1,882 in June 2025 and roughly 1,997 by July 2025 in various public trackers.)

  
  

What the MDL does (briefly): it centralizes discovery and pretrial proceedings to avoid duplicated effort and inconsistent rulings. It does not decide guilt or award damages for all plaintiffs at once — some cases may be selected as “bellwether” trial candidates or be remanded to district courts later.

Bottom line

Semaglutide-containing drugs have real benefits for many patients, but a small number of serious adverse signals — most notably NAION (vision loss) and severe GI injury including gastroparesis — have generated clinical concern, regulatory review, and widespread litigation. Regulators (in Europe) have required NAION to be listed as a very rare adverse effect, and hundreds–thousands of U.S. personal-injury suits were consolidated into MDL No. 3094 in the Eastern District of Pennsylvania to handle common legal issues involving GI injuries and warnings. If you’re on one of these drugs and have new or alarming symptoms, get medical care immediately and discuss next steps with your provider.