GLP-1 Medication Comparison

Retatrutide vs Tirzepatide — Full GLP-1 Comparison

The retatrutide vs tirzepatide comparison below is built from publicly available clinical trial data and published research. Both retatrutide and tirzepatide are GLP-1 class medications developed by Eli Lilly, but they differ in receptor mechanism, FDA approval status, weight loss trial results, and availability. Use this retatrutide vs tirzepatide reference to organize your questions before speaking with your own healthcare provider.

Last reviewed: April 21, 2026 · Updated with Phase 3 TRIUMPH-4 data · Primary sources: NEJM, Eli Lilly, ClinicalTrials.gov

Quick Answer — Retatrutide vs Tirzepatide

Retatrutide is a triple agonist (GLP-1 + GIP + glucagon) currently in Phase 3 trials, showing stronger early weight loss data. Tirzepatide is a dual agonist (GLP-1 + GIP) that is FDA-approved as Mounjaro and Zepbound and commercially available by prescription. In the retatrutide vs tirzepatide comparison, retatrutide appears more aggressive in early research, but tirzepatide currently has the advantage in regulatory approval, real-world availability, and longer safety follow-up.

Educational use only. This retatrutide vs tirzepatide comparison tool compiles publicly available research and clinical trial data for informational purposes. It does not provide medical advice, diagnosis, or treatment recommendations. Retatrutide is an investigational drug and is not FDA-approved. Always consult a qualified, licensed healthcare provider before making any medical decisions.

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Retatrutide vs Tirzepatide — Interactive Comparison Tool

Filter by category to explore specific aspects of the retatrutide vs tirzepatide comparison — mechanism, trial results, side effects, or FDA status. All retatrutide vs tirzepatide data is sourced from published clinical research and updated as new trial readouts are released.

What it is
A triple hormone receptor agonist that targets GLP-1, GIP, and glucagon receptors. Retatrutide is investigational and remains in Phase 3 clinical development.
A dual hormone receptor agonist that targets GLP-1 and GIP receptors. Tirzepatide is FDA-approved under the brand names Mounjaro and Zepbound.
Developer
Eli Lilly and Company
Eli Lilly and Company
Administration
Once-weekly subcutaneous injection in clinical trials
Once-weekly subcutaneous injection by prescription
Receptors targeted
Triple agonist
GLP-1, GIP, and glucagon receptors. The glucagon receptor component is a major difference in the retatrutide vs tirzepatide comparison.
Dual agonist
GLP-1 and GIP receptors only, without glucagon receptor activation.
Glucagon receptor activity
Yes. This may contribute to increased energy expenditure and may help explain stronger weight loss signals in early trial data.
No. Tirzepatide does not include glucagon receptor agonism.
Best known weight loss trial result
Phase 3 TRIUMPH-4 topline data reported mean body weight reduction of 28.7% at 68 weeks in adults with obesity or overweight and knee osteoarthritis.
SURMOUNT-1 reported mean body weight reduction up to 20.9% at 72 weeks in adults with obesity or overweight without diabetes.
Trial stage
Phase 3 clinical development
Approved medication with large Phase 3 trial data and post-market use
Other noted effects
TRIUMPH-4 also reported improvements in WOMAC pain and physical function in people with knee osteoarthritis, along with cardiometabolic improvements.
Tirzepatide has shown improvements in blood sugar, HbA1c, cardiometabolic markers, and weight-management outcomes across multiple trials.
Common side effects
Nausea, vomiting, diarrhea, constipation, and decreased appetite are commonly reported during dose escalation in trial participants.
Nausea, vomiting, diarrhea, constipation, and decreased appetite are also common, especially during dose initiation and escalation.
Long-term safety data
Limited. Long-term safety data is still developing because retatrutide remains investigational.
More established. Tirzepatide has broader clinical exposure and real-world use since approval.
FDA approval status
Not FDA-approved. Retatrutide is investigational and currently limited to research settings.
FDA-approved. Tirzepatide is approved as Mounjaro for type 2 diabetes and Zepbound for chronic weight management.
Availability
Not commercially available. Any online “retatrutide peptide” listings should not be treated as equivalent to regulated clinical-trial drug supply.
Commercially available by prescription through licensed healthcare providers and approved dispensing channels.
Can I get it now?
Only through participation in an active clinical trial, if eligible.
Yes, if prescribed by a licensed healthcare provider and clinically appropriate.
Retatrutide vs tirzepatide — data source note: This comparison includes published and publicly released data from Phase 2 and Phase 3 programs, including the NEJM retatrutide Phase 2 paper, Eli Lilly TRIUMPH-4 results, and SURMOUNT-1 tirzepatide results. Trial figures represent group averages in specific populations and do not predict individual outcomes. Last reviewed: April 21, 2026.

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Primary sources

Sources & outbound links

These are the primary external sources used for this retatrutide vs tirzepatide comparison. They open in a new tab.

Retatrutide Phase 2 trial — New England Journal of Medicine

Peer-reviewed Phase 2 trial data on retatrutide in adults with obesity.

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TRIUMPH-4 Phase 3 topline results — Eli Lilly

Company press release summarizing Phase 3 retatrutide results in obesity and knee osteoarthritis.

View source

SURMOUNT-1 tirzepatide trial — New England Journal of Medicine

Peer-reviewed Phase 3 trial results for tirzepatide in adults with obesity or overweight.

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ClinicalTrials.gov

Registry source for ongoing retatrutide and tirzepatide clinical trials and study details.

View source

Mounjaro prescribing information

FDA-approved prescribing information for tirzepatide as Mounjaro.

View source

Zepbound prescribing information

FDA-approved prescribing information for tirzepatide as Zepbound.

View source

Full disclaimer — retatrutide vs tirzepatide comparison

This retatrutide vs tirzepatide comparison tool is provided by ABX Apps for educational and informational purposes only. The information presented is compiled from publicly available clinical trial data, peer-reviewed research, and published regulatory materials. ABX Apps does not sell, prescribe, source, or recommend any medication, including retatrutide or tirzepatide.

Nothing on this page constitutes medical advice, diagnosis, or a treatment recommendation. Individual results vary. Trial data reflects averages across study populations and may not apply to any one individual.

Retatrutide is an investigational drug that is not approved by the FDA. It is not legally available for routine purchase or use outside authorized clinical trials.

Always consult a qualified, licensed healthcare provider before making decisions about medications, side effects, dose changes, or clinical trial participation.

Editorial disclosure — RetaSupport

This retatrutide vs tirzepatide page is written and maintained by a licensed clinical social worker who is also a personal GLP-1 user. All clinical data referenced is sourced to primary literature, Eli Lilly materials, and trial registries.

The author’s clinical background informs the behavioral and psychological discussion on topics like food noise, emotional adjustment, and access stress, but this page is not clinical care and should not be treated as healthcare guidance.

ABX Apps does not have a paid commercial relationship with Eli Lilly, Novo Nordisk, or any GLP-1 manufacturer. No sponsored placement appears on this page.

Retatrutide vs tirzepatide comparison compiled from publicly available research. No personal medical advice. © 2026 ABX Apps

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