GLP-1 Litigation Explodes: 4,400+ Lawsuits Filed as Bellwether Trials Approach

The wave of litigation against GLP-1 drug manufacturers has reached a critical inflection point. At least 4,400 patients have now filed lawsuits alleging Ozempic, Wegovy, and Mounjaro caused severe gastrointestinal injuries and vision loss, according to USA Today's analysis of consolidated federal and state litigation. With 75% of federal cases alleging gastroparesis—a debilitating condition where the stomach stops emptying food properly—and bellwether trials expected mid-2026, law firms handling mass tort cases face mounting pressure to build evidence-ready case files.

The litigation targets drugs used by more than 31 million Americans. A KFF poll found that 12% of U.S. adults currently take a GLP-1 medication for weight loss, diabetes, or other conditions—making this one of the largest potential plaintiff pools in recent pharmaceutical litigation history.

The Science Driving the Lawsuits

The legal claims rest on mounting scientific evidence. A landmark 2023 JAMA study found GLP-1 users face significantly elevated risks: 3.67 times higher risk of gastroparesis, 4.22 times higher risk of bowel obstruction, and 9.09 times higher risk of pancreatitis compared to patients using other weight loss medications.

These aren't isolated findings. A separate Harvard study published in JAMA Ophthalmology in July 2024 identified a troubling connection between semaglutide (the active ingredient in Ozempic and Wegovy) and non-arteritic anterior ischemic optic neuropathy (NAION)—commonly called an "eye stroke." The risk was 4.28 times higher for diabetic patients and 7.64 times higher for those using the drugs for weight loss.

Plaintiffs argue these risks weren't adequately communicated. "We think that the full panoply of conditions that this set of drugs can cause are not fully warned of," Jonathan Orent, co-lead counsel for plaintiffs in the MDL, told USA Today. "Until that happens, people are continuing to get hurt without having the full information."

Two MDLs, Two Distinct Injury Categories

The litigation has split into parallel tracks. MDL 3094, created in February 2024 in the Eastern District of Pennsylvania, consolidates gastrointestinal injury claims. A second MDL—MDL 3163—was established in December 2025 specifically for NAION vision loss claims.

This separation reflects the distinct medical expertise required for each injury type. According to court filings reported by USA Today, the breakdown of allegations in the GI litigation includes:

• 75% allege gastroparesis (stomach paralysis)
• 18% allege ileus (bowel dysfunction)
• 18% allege intestinal obstructions
• 8% allege gallbladder injuries requiring surgery
• 110+ plaintiffs allege sudden blindness or severe vision changes

Court-Mandated Evidence Standards

A critical August 2025 ruling reshaped what firms need to prove these cases. Judge Karen S. Marston mandated that all plaintiffs demonstrate gastroparesis through objective diagnostic testing—specifically gastric emptying scintigraphy, breath tests, or wireless motility capsules performed at the time of diagnosis.

The court rejected claims based solely on clinical presentation. Studies showed that retained gastric food—a common symptom—has only 32-67% positive predictive value depending on the patient population. This means firms must retrieve specific GI specialist records containing these diagnostic tests, not just ER visits or primary care notes documenting symptoms.

Vision Loss Claims Face Similar Hurdles

For NAION cases, the evidentiary burden includes ophthalmology records documenting the sudden vision loss, ruling out other causes, and establishing the timeline between drug use and injury onset. The European Medicines Agency confirmed NAION as a "very rare" side effect affecting up to 1 in 10,000 patients taking semaglutide for at least one year—a benchmark plaintiffs may use to establish foreseeability.

What This Means for Firms in 2026

With bellwether trials expected mid-2026, the window for case development is narrowing. According to MDL Update, expert discovery is due in March 2026 and summary judgment motions are scheduled for April.

The Records Challenge

GLP-1 cases present a unique retrieval complexity. A single plaintiff may have records spread across:

• Primary care physicians who prescribed the medication
• Pharmacies documenting fill dates and dosages
• Gastroenterologists performing diagnostic testing
• Emergency rooms treating acute symptoms
• Hospitals for surgical interventions
• Ophthalmologists for vision loss claims

The court's mandate for objective diagnostic testing means incomplete GI specialist records can be case-ending. Firms that relied on ER records or PCP notes documenting symptoms—without the required gastric emptying studies—face significant evidentiary gaps.

The Bottom Line

GLP-1 litigation has grown from the first lawsuit in August 2023 to over 4,400 consolidated cases in under three years—making it one of the fastest-growing pharmaceutical MDLs in recent history. With 31 million Americans currently using these drugs and bellwether trials approaching, the litigation's trajectory will likely accelerate.

For law firms, the path forward requires comprehensive medical evidence. Court-mandated diagnostic standards, two parallel MDLs with distinct injury profiles, and compressed timelines before bellwether trials all point to the same conclusion: complete medical record retrieval—across multiple provider types—is no longer optional. It's the foundation of case viability.

Sources: USA Today, JAMA, JAMA Ophthalmology, FDA, Reuters, KFF, MDL Update, Drugwatch, About Lawsuits.