Mounjaro Lawsuits: What's Alleged and Where Cases Stand in 2026

Mounjaro is one of the drugs named in MDL No. 3094, a federal multidistrict litigation in Philadelphia over gastrointestinal injuries that plaintiffs tie to GLP-1 receptor agonist drugs. The court’s description of the litigation names Trulicity and Mounjaro as Eli Lilly’s drugs in it ^[1], and Lilly’s May 19, 2026 brief lists Zepbound among its medicines at issue as well ^[4]. The litigation centers on three claims: that the manufacturers knew or should have known the drugs can cause gastroparesis and other gastrointestinal injuries, that they failed to adequately warn patients and prescribers, and that they made false, misleading, or incomplete safety statements ^[1]. Eli Lilly denies the allegations ^[1]. Nearly 3,000 gastroparesis lawsuits were pending in the MDL as of December 15, 2025, according to court records cited by Reuters ^[9].

The core of the case against Lilly was scheduled to be tested at a Rule 702 evidentiary hearing, often called a Daubert hearing, that Judge Karen S. Marston set for September 14 through September 18, 2026, on two cross-cutting issues: whether the drug labels adequately warned prescribers, and whether plaintiffs have admissible expert evidence that the drugs can cause the alleged injuries at all ^[1][4]. Lilly, in a May 19, 2026 roadmap brief, has asked the court to exclude plaintiffs’ expert opinions and to rule in Lilly’s favor without a trial ^[4]. The litigation is in pretrial proceedings; Lilly’s motions and the September 2026 hearing are where it stands in the documented record ^[1][4].

What is MDL 3094 and which drugs does it name?

MDL No. 3094, In re: Glucagon-like Peptide-1 Receptor Agonists (GLP-1 RAs) Products Liability Litigation (GI Injuries), is a group of personal injury lawsuits consolidated for pretrial proceedings in the U.S. District Court for the Eastern District of Pennsylvania, before Judge Karen S. Marston ^[1]. The court’s description of the litigation names Ozempic, Wegovy, and Rybelsus, made by Novo Nordisk defendants, and Trulicity and Mounjaro, made by Eli Lilly ^[1]. The gastroparesis lawsuits were centralized before Marston in February 2024 ^[9].

Lilly’s own May 19, 2026 brief lists three of its medicines at issue in the MDL: Trulicity (dulaglutide), approved in September 2014 to treat type 2 diabetes; Mounjaro (tirzepatide), approved in May 2022 to treat type 2 diabetes; and Zepbound (tirzepatide), approved in November 2023 for chronic weight management ^[4]. So both tirzepatide products, Mounjaro and Zepbound, are part of this litigation alongside Trulicity, per Lilly’s brief ^[4].

Is the GLP-1 litigation a class action?

No. It is a multidistrict litigation, not a class action. The Judicial Panel on Multidistrict Litigation found that the actions “involve common questions of fact, and that centralization in the Eastern District of Pennsylvania will serve the convenience of the parties and witnesses and promote the just and efficient conduct of this litigation” ^[1]. In an MDL, individual lawsuits are transferred to one court for coordinated pretrial work, but each case remains its own lawsuit. That is different from a class action, where one case is brought on behalf of a group.

As of December 15, 2025, there were nearly 3,000 gastroparesis lawsuits in the MDL, according to court records cited by Reuters ^[9]. Lilly’s May 2026 brief states that gastroparesis claims still make up more than 60% of the MDL cases against Lilly ^[4].

What do plaintiffs allege the companies knew and failed to warn about?

According to the MDL panel’s order, all the actions share three common questions of fact ^[1]:

• Whether the defendants knew or should have known that their GLP-1 RA products can cause gastroparesis and other gastrointestinal injuries.
• Whether the defendants adequately warned plaintiffs or their prescribing physicians about the alleged dangers of these products.
• Whether the defendants made false, misleading, or incomplete representations regarding the safety of these products.

The Novo Nordisk defendants and Eli Lilly deny these allegations ^[1]. Reuters reported that the companies have argued in court filings that the risk of gastroparesis is well-publicized and that they cannot change the drugs’ design without FDA approval ^[9].

What injuries are alleged against Lilly’s drugs?

In its May 19, 2026 brief, Lilly summarizes what plaintiffs claim: that Lilly failed to adequately warn about alleged side effects including gastroparesis, gallbladder disease (gallstones and inflammation), ileus (stopped bowel motility), and intestinal obstruction (bowel blockage), among others ^[4]. Other alleged injuries listed in the brief include pancreatitis, malnutrition, micronutrient deficiencies, Wernicke’s encephalopathy, muscle wasting, dehydration, acute kidney injury, and aspiration ^[4].

The brief also notes a limit on one part of the case: general causation, known as Issue 3, is limited to four alleged injuries — gastroparesis, ileus, small bowel obstruction, and gallbladder injuries ^[4].

What does the Zepbound label already say about these risks?

The FDA-approved prescribing information for Zepbound already carries warnings covering many of the conditions at issue in the lawsuits. Section 5.2 of the label states that use of Zepbound has been associated with gastrointestinal adverse reactions, sometimes severe, and that Zepbound is not recommended in patients with severe gastroparesis ^[10].

In a pool of two Zepbound clinical trials for weight reduction, severe gastrointestinal adverse reactions were reported more frequently among patients receiving Zepbound than placebo ^[10].

Zepbound dose	Severe GI adverse reactions	Placebo
5 mg	1.7%	1%
10 mg	2.5%	1%
15 mg	3.1%	1%

The label’s postmarketing section (6.2) lists reported reactions including ileus, intestinal obstruction, and severe constipation including fecal impaction, while stating that because these reports come voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to the drug ^[10]. The label’s warnings also cover acute gallbladder disease, acute pancreatitis, acute kidney injury due to volume depletion, and pulmonary aspiration during general anesthesia or deep sedation ^[10]. These figures come from the Zepbound label.

What is the September 2026 Daubert hearing about?

Judge Marston scheduled a Rule 702 evidentiary hearing, also called a Daubert hearing, for September 14 through September 18, 2026, on Cross Cutting Issues 2 and 3 ^[1]. Rule 702 is the federal rule governing when expert testimony is admissible.

Issue 2 asks whether plaintiffs can show that Lilly’s FDA-approved labels failed to adequately warn prescribing physicians about the risks, and whether any claims are preempted by federal law ^[4]. Issue 3 asks whether there is sufficient admissible expert testimony on general causation — that is, whether Lilly’s medicines can cause the alleged side effects at all ^[4]. Expert testimony is required to show general causation, according to the case law cited in Lilly’s brief ^[4].

The hearing was scheduled for those dates ^[1].

What is Lilly’s defense?

Lilly laid out its defense in a roadmap brief filed May 19, 2026. It is a party’s own filing, so its arguments are Lilly’s positions, not court findings. Lilly describes a series of motions to exclude plaintiffs’ expert opinions and motions for summary judgment, organized by injury group: gastroparesis, ileus and obstruction, gallbladder disease, and other gastrointestinal and miscellaneous claims ^[4].

On preemption, Lilly argues that claims are preempted if there is either insufficient “newly acquired information” that would have allowed a company to unilaterally change an FDA-approved label, or “clear evidence” that the FDA would have rejected a different warning ^[4]. Lilly also argues that claims are preempted where the FDA considered and rejected additional gastroparesis warnings ^[4].

Lilly’s Motion 9 seeks summary judgment on claims involving malnutrition, micronutrient deficiency, Wernicke’s encephalopathy, and muscle wasting, arguing there is clear evidence the FDA would have rejected, and did reject, additional warnings for those conditions ^[4]. Lilly notes that plaintiffs offer no expert opinions at all about warning inadequacy for a number of alleged injuries, such as malnutrition and pancreatitis ^[4]. Motions 7, 10, and 11 are joint motions filed with Novo Nordisk ^[4].

What do plaintiffs’ experts say about tirzepatide specifically?

Lilly’s brief argues that the plaintiffs’ expert opinions are narrower than the lawsuits suggest, particularly for tirzepatide. According to Lilly ^[4]:

• Dr. David Kessler, a former FDA Commissioner, and Dr. David Ross, a former FDA medical reviewer, offer no opinions related to tirzepatide (Mounjaro or Zepbound). Their opinions concern Trulicity labels only. Plaintiffs confirmed that Dr. Kessler will not opine on label adequacy for Mounjaro or Zepbound ^[4].
• Dr. David Metz, a retired gastroenterologist, defines drug-induced gastroparesis as symptoms lasting up to six months after stopping the medicine, and opines that causality of prolonged symptoms after cessation cannot be supported ^[4].
• Drs. Nilesh Lodhia and Binu John opine that GLP-1 RA medicines can cause ileus and intestinal obstruction but offer no opinions on any individual Lilly medicine. Dr. Joseph Pisegna opines it is biologically plausible that tirzepatide can cause ileus ^[4].
• Dr. Gabriel Lang opines that GLP-1 RA medicines as a class can cause gallbladder disease but could not reliably conclude that a cause-and-effect relationship exists between individual Lilly medicines and gallbladder disease ^[4].

In total, Lilly counts ten plaintiffs’ experts with Lilly-related opinions, and notes that plaintiffs withdrew Dr. David Madigan’s expert report and opinions as to Lilly after his deposition ^[4].

Is there a Mounjaro vision loss or NAION lawsuit?

There is a second GLP-1 MDL over vision loss, MDL No. 3163, and the drugs named by plaintiffs in it are Ozempic, Wegovy, Saxenda, and Trulicity ^[2][3]. On December 15, 2025, the JPML created MDL No. 3163, In re: GLP-1 RAs Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION) Products Liability Litigation, before Judge Marston, covering 21 actions pending in three districts plus nine related actions ^[3][9].

Eli Lilly had moved to centralize the NAION cases in the Eastern District of Pennsylvania or to fold them into MDL 3094; plaintiffs sought the District of New Jersey. The panel chose the Eastern District of Pennsylvania but declined to merge the cases into MDL 3094 ^[3]. The NAION actions bring claims for failure to warn, design defect, and breach of warranties ^[2][3]. Reuters reported that as of December 15, 2025, there were 30 optic neuropathy lawsuits pending in federal court and more than 40 in state court, and that the filings followed a July 2024 study describing the potential risk ^[9].

What is the Texas attorney general’s lawsuit against Lilly about?

On August 12, 2025, Texas Attorney General Ken Paxton, with co-plaintiff Health Choice Alliance, sued Eli Lilly under the Texas Health Care Program Fraud Prevention Act ^[6][11]. The suit alleges that Lilly offered illegal incentives to medical providers in Texas — a “Free Nurse Program” providing free patient-care services and a “Support Services Program” providing reimbursement support — to steer providers toward prescribing Lilly drugs, including Mounjaro and Zepbound ^[6][11]. The suit further alleges that many of those prescriptions were covered by Medicaid, resulting in millions of dollars in claims to Texas Medicaid that the suit says were tainted by the arrangements ^[6][11].

The suit also names drugs including Basaglar, Ebglyss, Emgality, several insulin presentations, and Taltz ^[11]. Lilly said it will vigorously defend against the allegations, noting that a prior Health Choice Alliance suit filed in 2017 was dismissed in August 2018 and that the Fifth Circuit upheld the dismissal in 2021 ^[11].

What was the FDA warning letter to Lilly about?

Separately from the lawsuits, the FDA sent Eli Lilly a warning letter on September 9, 2025, concerning a direct-to-consumer video, “An Oprah Special: Shame, Blame, and the Weight Loss Revolution,” regarding Zepbound and Mounjaro. The video aired on ABC on March 18, 2024, and on Hulu on March 19, 2024 ^[7].

The FDA determined the video was false or misleading and misbranded the drugs ^[7]. Among other findings, the FDA said a paid consultant stated, in response to a question about pancreatitis, gallbladder complications, and concerns for thyroid cancer, that “the risk is less than 1%”; that the video omitted the MEN 2 contraindication from the boxed warning; and that it omitted warnings about severe gastrointestinal disease, acute kidney injury, hypersensitivity, hypoglycemia, diabetic retinopathy complications, and suicidal behavior and ideation ^[7]. The letter also noted FDA advisory comments dated June 13 and June 21, 2022, on draft Mounjaro promotional presentations, in which the FDA recommended revisions to avoid minimizing gastrointestinal risks ^[7].

Where is Lilly the plaintiff instead of the defendant?

Lilly has also gone to court as a plaintiff. On April 23, 2025, Lilly sued four telehealth companies — Mochi Health, Fella Health, Willow Health, and Henry Meds — over compounded tirzepatide ^[8]. Lilly alleges the companies deceive consumers about “untested, unapproved drugs” and sell unstudied formulations such as oral tablets and drops ^[8]. Earlier in April 2025, Lilly sued two pharmacies making similar claims; Mochi Health has said its model complies with FDA guidance ^[8]. According to CNBC, mass compounding of tirzepatide was supposed to stop the month before these suits, after the FDA declared the shortage of the drugs over, and Lilly is seeking to stop the sites from marketing or selling compounded versions ^[8].

What is still open, and what is separate from the legal fight?

The record documented here runs through Lilly’s May 19, 2026 brief and the Rule 702 hearing scheduled for September 14 through September 18, 2026 ^[1][4]. Lilly’s summary judgment motions are the company’s own arguments, not court findings ^[4]. Reuters reported that the companies argue the gastroparesis risk is well-publicized and that design changes require FDA approval ^[9].

The legal questions are separate from medical ones. Whether a drug caused a particular person’s injury is what these cases exist to sort out, and nothing here settles it. Anyone with symptoms they are concerned about — persistent vomiting, inability to keep food down, severe abdominal pain — should raise them with a clinician. Anyone wondering about their own legal options can talk to a lawyer of their choosing.

Sources

1. US District Court, Eastern District of Pennsylvania. MDL 3094 In Re: Glucagon-like Peptide-1 Receptor Agonists (GLP-1 RAs) Products Liability Litigation (GI Injuries).
2. US District Court, Eastern District of Pennsylvania. MDL 3163 In Re: Glucagon-like Peptide-1 Receptor Agonists (GLP-1 RAs) Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION) Products Liability Litigation.
3. US Judicial Panel on Multidistrict Litigation. In re: Glucagon-like Peptide-1 Receptor Agonists (GLP-1 RAs) Non-Arteritic Anterior Ischemic Optic Neuropathy Products Liability Litigation, MDL No. 3163, transfer order. December 15, 2025.
4. King Law. Mounjaro lawsuit: expert motions roadmap. May 2026.
5. US Judicial Panel on Multidistrict Litigation. Pending MDLs, as of September 1, 2026.
6. Office of the Texas Attorney General. Attorney General Ken Paxton sues Big Pharma drug manufacturer Eli Lilly for bribing providers to prescribe its medications.
7. US Food and Drug Administration. Warning letter: Eli Lilly and Company, 716485. September 9, 2025.
8. CNBC. Eli Lilly sues compounded Mounjaro, Zepbound providers. April 23, 2025.
9. Reuters. Lawsuits claiming Ozempic, other GLP-1s led to blindness become second mass litigation over the drugs. December 15, 2025.
10. National Library of Medicine, DailyMed. Zepbound (tirzepatide) injection, solution.
11. Fierce Pharma. Eli Lilly pledges vigorous defense as Texas sues over alleged drug kickbacks. August 12, 2025.