GLP-1 Litigation at Crossroads: What the September Daubert Hearing Means for 4,025 Pending Claims

With 4,025 cases pending in the federal GLP-1 gastrointestinal injury litigation as of October 1, 2026, the next major decision could affect how thousands of claims proceed. From September 14 to 18, 2026, Judge Karen Spencer Marston presided over a Rule 702 evidentiary hearing that could reshape thousands of lawsuits involving GLP-1 medications.[1]

The court has not announced its decision. The outcome could affect whether important expert opinions are admitted. For personal injury firms, the immediate concern is not simply the number of pending cases. It is whether the scientific evidence and medical records supporting those cases can withstand the litigation’s evolving evidentiary requirements.

What Is at Stake: The Numbers First

The 4,025 pending cases is more than three times its 2024 size. Medications such as Ozempic, Wegovy, Mounjaro and Zepbound have attracted growing legal attention over alleged gastrointestinal injuries.[2]

Litigation trackers estimate that roughly 75% of complaints involve gastroparesis, 18% allege ileus and 8% concern gallbladder injuries. Severe gastroparesis can leave patients struggling with persistent vomiting, difficulty eating, repeated hospitalizations and, sometimes, feeding tubes.[3] The question is whether plaintiffs can establish that these medications caused their injuries.

What the Hearing Actually Addressed

Three issues dominate the dispute: general causation, warning adequacy and federal preemption. General causation asks whether GLP-1 medications can cause the injuries alleged. Without admissible expert testimony supporting that connection, many claims may struggle to proceed. Plaintiffs also argue that Novo Nordisk and Eli Lilly failed to provide adequate warnings about serious gastrointestinal risks. Both manufacturers deny the allegations. Federal preemption adds another layer. Defendants argue that federal regulatory requirements limit certain state-law failure-to-warn claims. [4]

The Science Plaintiffs Are Relying On

Plaintiffs point to research suggesting an association between GLP-1 use and gastroparesis. A 2023 JAMA study reported an adjusted hazard ratio of 3.67 compared with an alternative weight-loss medication.[5] A May 2026 study, reported as appearing in the Journal of Nuclear Medicine, found that GLP-1 users were approximately 2.7 times more likely to receive a new gastroparesis diagnosis following gastric-emptying testing.[6]

The defense sees the evidence differently. GLP-1 medications are known to slow gastric emptying, but manufacturers argue this temporary effect does not necessarily establish permanent gastroparesis. They also suggest the drugs may reveal previously existing conditions. Judge Marston must decide whether the experts’ methods are reliable enough for jury consideration.

The Gastroparesis Ruling That Already Narrowed the Field

In August 2025, Judge Marston required objective gastric-emptying studies to support gastroparesis diagnoses. She rejected alternative diagnostic methodologies after finding that the experts had not adequately demonstrated their reliability.[7]

That ruling made medical documentation particularly important. A patient’s symptoms alone may not satisfy the court’s evidentiary requirements. For firms reviewing their inventories, cases supported by objective testing warrant careful attention.

The Two Outcomes and What Each Means

If plaintiffs’ general causation experts survive Daubert scrutiny, litigation could move toward bellwether trials. Defendants have proposed completing fact discovery in October 2026, expert discovery by year-end and motion briefing in early 2027. Those trials could eventually influence settlement discussions, although neither verdicts nor settlements are guaranteed. If the experts are excluded, however, causation-dependent claims could face summary judgment. Plaintiffs’ firms might then need to reassess their inventories, while defendants could gain substantial negotiating leverage.

The Parallel NAION Track: A Second MDL Watching Closely

A separate proceeding, MDL-3163, involves 247 pending cases as of October 1, alleging that GLP-1 medications cause non-arteritic anterior ischemic optic neuropathy (NAION), a condition associated with sudden vision loss.[8]

Although the proceedings are separate, the gastrointestinal litigation may offer insight into how the court evaluates disputed scientific testimony.

What PI Firms with GLP-1 Cases Should Do Right Now

With the ruling pending, firms should concentrate on case quality. Gastroparesis claims need appropriate diagnostic support, including gastric-emptying studies where required. Prescription records should establish use of the relevant branded medication rather than a compounded alternative. Equally important is the timeline as to when treatment began, when symptoms developed and when physicians confirmed the injury. Status conferences are scheduled for October 13, November 17 and December 15, 2026.[9]

The Bottom Line

MDL-3094 remains at a critical stage. The September hearing may determine whether thousands of claims advance toward trial or face significant procedural obstacles. For PI firms, the priority is straightforward, which is to strengthen case documentation, evaluate causation evidence carefully and watch Philadelphia for the next ruling.

[1] In re Glucagon-Like Peptide-1 Receptor Agonists (GLP-1 RAs) Prods. Liab. Litig., No. 2:24-md-03094 (E.D. Pa.); U.S. Dist. Ct. for the E. Dist. of Pa., GLP-1 Receptor Agonists Products Liability Litigation, https://www.paed.uscourts.gov/mdl/mdl-3094-re-glucagon-peptide-1-receptor-agonists-glp-1-ras-products-liability-litigation-gi.

[2] U.S. Jud. Panel on Multidistrict Litig., Pending MDLs by MDL Number (Oct. 1, 2026), https://www.jpml.uscourts.gov/pending-mdls-0. See also MDL 3094: Glucagon-Like Peptide-1 Receptor Agonists Products Liability, Settlement Record, https://settlementrecord.com/mdl/3094-glucagon-like-peptide-1-receptor-agonists (last visited Oct. 9, 2026).

[3] MDL 3094: Glucagon-Like Peptide-1 Receptor Agonists Products Liability, MDL Update, https://mdlupdate.com/mdl/3094-glucagon-like-peptide-1-receptor-agonists/

[4]  Supra note 1

[5] Mohit Sodhi et al., Risk of Gastrointestinal Adverse Events Associated with Glucagon-Like Peptide-1 Receptor Agonists for Weight Loss, 330 JAMA 1795, 1795–97 (2023), https://doi.org/10.1001/jama.2023.19574.

[6] Miles, B. & Oza, U. (2026). The Potential Impact of GLP-1 Use on Gastroparesis Diagnoses Made by Nuclear Imaging: A Global, Propensity-Score Matched Study. Journal of Nuclear Medicine, 67(Suppl. 1), Abstract 262555. https://jnm.snmjournals.org/content/67/supplement_1/262555

[7] In re Glucagon-Like Peptide-1 Receptor Agonists (GLP-1 RAs) Prods. Liab. Litig., No. 2:24-md-03094, Doc. 467 (E.D. Pa. Aug. 15, 2025) (memorandum addressing Cross-Cutting Issue No. 1).

[8] In re Glucagon-Like Peptide-1 Receptor Agonists (GLP-1 RAs) Prods. Liab. Litig. (NAION), MDL No. 3163 (J.P.M.L. Dec. 15, 2025) (transfer order), https://www.jpml.uscourts.gov/sites/jpml/files/MDL-3163-Transfer_Order-12-25.pdf.

See also U.S. Jud. Panel on Multidistrict Litig., Pending MDLs by MDL Number, supra note 2.

[9] U.S. Dist. Ct. for the E. Dist. of Pa., In re Glucagon-Like Peptide-1 Receptor Agonists (GLP-1 RAs) Products Liability Litigation, MDL No. 3094, https://www.paed.uscourts.gov/mdl/mdl-3094-re-glucagon-peptide-1-receptor-agonists-glp-1-ras-products-liability-litigation-gi