Mounjaro vs. Ozempic: Why the Risk Profiles Are Different and What It Means for Litigation

Not all GLP-1 drugs are the same. And as litigation unfolds across two MDLs and thousands of lawsuits, understanding the differences between tirzepatide (Mounjaro, Zepbound) and semaglutide (Ozempic, Wegovy) isn't just medically relevant — it's strategically critical.

The FAERS Divergence

The most striking data point: according to FDA FAERS analysis, tirzepatide has zero reported gastroparesis cases — the injury at the center of 75% of GLP-1 federal lawsuits.

Semaglutide and liraglutide, by contrast, have substantial gastroparesis signal in the FDA database. This divergence suggests the mechanism of injury may be specific to certain GLP-1 receptor agonists rather than a class-wide effect.

Different Drugs, Different Risks

LEWS has been tracking risk signals across all 11 GLP-1 agonists on the market. Here's what the data shows:

Semaglutide (Ozempic, Wegovy, Rybelsus)

• Strong gastroparesis signal
• NAION (vision loss) association per JAMA Ophthalmology
• ~500 deaths in FAERS
• Pancreatitis reports
• Primary target of MDL 3094 and MDL 3163

Tirzepatide (Mounjaro, Zepbound)

• No gastroparesis in FAERS (as of latest data)
• Pancreatitis signal — UK audit found concerning patterns in one-year follow-up
• Diverticular stricture and hepatic abscess formation documented
• Osteoporosis risk identified in comparative studies
• Psychiatric safety concerns (studies in patients with schizophrenia spectrum disorders)

Liraglutide (Victoza, Saxenda)

• Gastroparesis signal present
• Longer track record (earlier approval)
• Thyroid cancer warnings on label

Dulaglutide (Trulicity)

• Moderate adverse event signal
• Less litigation activity to date

What This Means for Plaintiff Strategy

The temptation in mass tort is to lump all GLP-1 drugs together. The science doesn't support that approach.

For semaglutide cases: Gastroparesis and vision loss are the strongest claims. The FDA warning letter to Novo Nordisk for underreporting adverse events strengthens the failure-to-warn theory.

For tirzepatide cases: The injury profile is different. Pancreatitis, hepatic complications, and bone density loss may be the stronger claims. Eli Lilly faces different liability exposure than Novo Nordisk.

For case acquisition: Marketing "GLP-1 lawsuits" broadly will generate leads, but firms that understand which injuries map to which drugs will convert more effectively and build stronger cases.

The Research Is Still Evolving

LEWS tracks over 14,700 published studies on GLP-1 safety. New research is published weekly. Recent additions to our system include:

• Tirzepatide psychiatric safety evaluation (February 2026)
• Comparative osteoporosis risk: tirzepatide vs. other GLP-1 RAs
• Idiopathic intracranial hypertension linked to GLP-1 use
• Anesthesia complication risks in GLP-1 patients (relevant for surgical injury claims)

The science is moving fast. The firms that stay current on the research — or have a system that does it for them — will be best prepared for Daubert challenges and bellwether trials.