Which has more human data?

Going by the research status on each profile (Tirzepatide: FDA-approved; Retatrutide: Phase 3), Tirzepatide is furthest along in human testing. Research status describes the stage of the published evidence, not whether a compound works or is safe.

What are the half-lives?

Tirzepatide: ~5 days. Retatrutide: ~6 days. Figures are as reported in the cited studies, with the species where stated.

Are they FDA-approved?

Tirzepatide: research status “FDA-approved”. FDA-approved. Removed from the FDA shortage list, so compounding of copies is restricted. Retatrutide: research status “Phase 3”. Investigational only - no FDA approval for any indication. Not a compoundable substance: it is not on the 503A bulks list, and it was not among the April 2026 Category 2 removals or the July 2026 PCAC votes. Compounded or grey-market 'retatrutide' is unapproved. See the FDA peptide regulatory tracker for sourced compounding status.

How are they administered in the research?

Tirzepatide: Subcutaneous injection. Retatrutide: Subcutaneous injection. This describes the published studies and is not a recommendation for human use.

How do their proposed mechanisms differ?

Tirzepatide: In plain terms: It acts on two gut-hormone receptors (GIP and GLP-1) and led to weight loss in a clinical trial. Dual GIP and GLP-1 receptor agonist, developed to test whether GIP's metabolic action adds to GLP-1 receptor agonism (Coskun 2018). Its effect on body weight comes from clinical trials: in the SURMOUNT-1 phase 3 RCT (n=2539), mean weight change at 72 weeks was -15.0% to -20.9% with 5-15 mg weekly vs -3.1% with placebo (Jastreboff 2022). Retatrutide: In plain terms: It acts on three gut-hormone receptors (GIP, GLP-1 and glucagon) and led to weight loss in a clinical trial. Agonist of the GIP, GLP-1 and glucagon receptors (Jastreboff 2023). Its effect on body weight comes from a 48-week phase 2 RCT in 338 adults with obesity, in which mean weight change at 48 weeks ranged from -8.7% (1 mg) to -24.2% (12 mg) vs -2.1% with placebo (Jastreboff 2023). These are mechanisms proposed in the cited research, at the research stage listed for each compound.

Tirzepatide vs Retatrutide: Research Comparison

Built from the Tirzepatide, Retatrutide research profiles · Profiles last updated October 1, 2026 · Reviewed by The Peptide Dispatch Editorial Team

TL;DR

This page compares Tirzepatide and Retatrutide using only their research-profile data. Tirzepatide (research stage: FDA-approved; half-life: About 5 days). It acts on two gut-hormone receptors (GIP and GLP-1) and led to weight loss in a clinical trial. Retatrutide (research stage: Phase 3; half-life: About 6 days). It acts on three gut-hormone receptors (GIP, GLP-1 and glucagon) and led to weight loss in a clinical trial. Educational summary, not medical advice.

Where each point comes from: Clinicalhuman trials and FDA labels Lab / animalrodent, cell and ex vivo studies Community-reporteduser experience and commonly used protocols, not from clinical studies

Educational summary. Everything below is taken from each compound's research profile and describes what was reported in the cited studies — not a promise of results, a dose recommendation, or an endorsement for human use. Not medical advice. Full disclaimer.

Side-by-side comparison

	Tirzepatide	Retatrutide
Category	Metabolic	Metabolic
Research status	FDA-approved	Phase 3
Regulatory note (as of Sept 2026)	FDA-approved. Removed from the FDA shortage list, so compounding of copies is restricted. Regulatory tracker →	Investigational only - no FDA approval for any indication. Not a compoundable substance: it is not on the 503A bulks list, and it was not among the April 2026 Category 2 removals or the July 2026 PCAC votes. Compounded or grey-market 'retatrutide' is unapproved. Regulatory tracker →
Half-life	~5 days	~6 days
Administration route	Subcutaneous injection	Subcutaneous injection
Dosing used in published research (not a recommendation)	Humans: 5, 10 or 15 mg s.c. once weekly for 72 weeks after a 20-week escalation, n=2539 (SURMOUNT-1, Jastreboff 2022). Phase 1: 0.25-15 mg (Coskun 2018).	1, 4, 8 or 12 mg subcutaneously once weekly for 48 weeks in a phase 2 double-blind placebo-controlled trial of 338 adults with obesity (escalation from 2 mg or 4 mg starting doses)
Community-reported protocol (not from clinical studies)	Community-reported2.5–15 mg weekly, subcutaneous injection	Community-reported1–12 mg weekly, subcutaneous injection
How it works (as summarized from the cited research)	In plain terms: It acts on two gut-hormone receptors (GIP and GLP-1) and led to weight loss in a clinical trial. Dual GIP and GLP-1 receptor agonist, developed to test whether GIP's metabolic action adds to GLP-1 receptor agonism (Coskun 2018). Its effect on body weight comes from clinical trials: in the SURMOUNT-1 phase 3 RCT (n=2539), mean weight change at 72 weeks was -15.0% to -20.9% with 5-15 mg weekly vs -3.1% with placebo (Jastreboff 2022).	In plain terms: It acts on three gut-hormone receptors (GIP, GLP-1 and glucagon) and led to weight loss in a clinical trial. Agonist of the GIP, GLP-1 and glucagon receptors (Jastreboff 2023). Its effect on body weight comes from a 48-week phase 2 RCT in 338 adults with obesity, in which mean weight change at 48 weeks ranged from -8.7% (1 mg) to -24.2% (12 mg) vs -2.1% with placebo (Jastreboff 2023).
Effects reported in research (study subjects as stated)	ClinicalMean 15-21% weight reduction at 72 weeks vs 3.1% with placebo (SURMOUNT-1 Phase 3 trial) ClinicalIn clinical use (FDA label): adjunct to diet and exercise to improve glycemic control in type 2 diabetes (Mounjaro)	ClinicalWeight loss in a phase 2 trial (n=338 adults with obesity): least-squares mean change of -24.2% at 48 weeks on 12 mg vs -2.1% on placebo
Potential side effects	ClinicalGI adverse events led to discontinuation in 4.3-7.1% vs 2.6% on placebo (SURMOUNT-1) Lab / animalThyroid C-cell tumor boxed warning (rodent data)	Gastrointestinal events (nausea, diarrhoea, vomiting) were the most common, dose-related, mostly mild to moderate, and partly mitigated by a 2 mg rather than 4 mg starting dose Dose-dependent increases in heart rate that peaked at 24 weeks and declined thereafter Long-term safety is not established; phase 3 outcome data are pending
Profile description	Dual GIP/GLP-1 receptor agonist. In the SURMOUNT-1 Phase 3 trial, mean weight reduction was 15-21% at 72 weeks vs 3.1% with placebo. Brand names include Mounjaro and Zepbound. Tirzepatide is a prescription-only medication and must be obtained and used under the supervision of a licensed healthcare provider.	Triple agonist targeting GIP, GLP-1, and glucagon receptors. In a phase 2 trial of 338 adults with obesity, the 12 mg dose produced a least-squares mean weight change of -24.2% at 48 weeks versus -2.1% on placebo.
References cited on the profile	2	2

Key differences in the published research

Research status: Tirzepatide — FDA-approved; Retatrutide — Phase 3.
FDA approval: only Tirzepatide carries an “FDA-approved” research status.
Category: the same on every profile (Metabolic).
Reported half-life: Tirzepatide — ~5 days; Retatrutide — ~6 days.
Administration route in the literature: the same on every profile (Subcutaneous injection).
Evidence cited: Tirzepatide’s profile lists 2 references; Retatrutide’s profile lists 2 references.

Regulatory status

Tirzepatide: On the FDA peptide regulatory tracker: FDA-approved drug. Details →
Retatrutide: Investigational only - no FDA approval for any indication. Not a compoundable substance: it is not on the 503A bulks list, and it was not among the April 2026 Category 2 removals or the July 2026 PCAC votes. Compounded or grey-market 'retatrutide' is unapproved. Details →

For the sourced, dated status of every peptide in FDA's 2026 compounding actions, see the FDA peptide regulatory tracker.

Frequently Asked Questions

Which has more human data?: Going by the research status on each profile (Tirzepatide: FDA-approved; Retatrutide: Phase 3), Tirzepatide is furthest along in human testing. Research status describes the stage of the published evidence, not whether a compound works or is safe.
What are the half-lives?: Tirzepatide: ~5 days. Retatrutide: ~6 days. Figures are as reported in the cited studies, with the species where stated.
Are they FDA-approved?: Tirzepatide: research status “FDA-approved”. FDA-approved. Removed from the FDA shortage list, so compounding of copies is restricted. Retatrutide: research status “Phase 3”. Investigational only - no FDA approval for any indication. Not a compoundable substance: it is not on the 503A bulks list, and it was not among the April 2026 Category 2 removals or the July 2026 PCAC votes. Compounded or grey-market 'retatrutide' is unapproved. See the FDA peptide regulatory tracker for sourced compounding status.
How are they administered in the research?: Tirzepatide: Subcutaneous injection. Retatrutide: Subcutaneous injection. This describes the published studies and is not a recommendation for human use.
How do their proposed mechanisms differ?: Tirzepatide: In plain terms: It acts on two gut-hormone receptors (GIP and GLP-1) and led to weight loss in a clinical trial. Dual GIP and GLP-1 receptor agonist, developed to test whether GIP's metabolic action adds to GLP-1 receptor agonism (Coskun 2018). Its effect on body weight comes from clinical trials: in the SURMOUNT-1 phase 3 RCT (n=2539), mean weight change at 72 weeks was -15.0% to -20.9% with 5-15 mg weekly vs -3.1% with placebo (Jastreboff 2022). Retatrutide: In plain terms: It acts on three gut-hormone receptors (GIP, GLP-1 and glucagon) and led to weight loss in a clinical trial. Agonist of the GIP, GLP-1 and glucagon receptors (Jastreboff 2023). Its effect on body weight comes from a 48-week phase 2 RCT in 338 adults with obesity, in which mean weight change at 48 weeks ranged from -8.7% (1 mg) to -24.2% (12 mg) vs -2.1% with placebo (Jastreboff 2023). These are mechanisms proposed in the cited research, at the research stage listed for each compound.

References

Tirzepatide

Tirzepatide Once Weekly for the Treatment of Obesity
Jastreboff AM, Aronne LJ, Ahmad NN, Wharton S, Connery L, Alves B et al. The New England journal of medicine. 2022. PMID: 35658024.
Study type: Phase 3 RCT n=2539 (SURMOUNT-1).
DOI: 10.1056/NEJMoa2206038 · PubMed
LY3298176, a novel dual GIP and GLP-1 receptor agonist for the treatment of type 2 diabetes mellitus: From discovery to clinical proof of concept
Coskun T, Sloop KW, Loghin C, Alsina-Fernandez J, Urva S, Bokvist KB et al. Molecular metabolism. 2018. PMID: 30473097.
Study type: Phase 1 RCT n=142.
DOI: 10.1016/j.molmet.2018.09.009 · PubMed

Retatrutide

Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial
Jastreboff AM, Kaplan LM, Frías JP, Wu Q, Du Y, Gurbuz S et al. The New England journal of medicine. 2023. PMID: 37366315.
Study type: Phase 2 double-blind randomized placebo-controlled trial, n=338 adults with obesity, 48 weeks.
DOI: 10.1056/NEJMoa2301972 · PubMed
The First Triple Agonist for Antiobesity: Retatrutide
Tetelbaun L, Mullally JA, Frishman WH. Cardiology in review. 2024. PMID: 39724554.
Study type: Review of phase 1 and 2 clinical trial data.
DOI: 10.1097/CRD.0000000000000793 · PubMed

Read the full profiles

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Educational content — not medical advice. Effects described are drawn from cited research in study subjects.

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