# Retatrutide vs Tirzepatide: How They Differ | PepVault Source: https://pepvault.app/peptides/compare/retatrutide-vs-tirzepatide Last updated: 2026-10-12 [Library](https://pepvault.app/peptides) [Comparisons](https://pepvault.app/peptides/compare) Retatrutide vs Tirzepatide Compared side by side # Retatrutide vs tirzepatide: how they differ Reviewed October 2026 [How we check the library](https://pepvault.app/about#library) ## The short answer Tirzepatide is a dual GIP/GLP-1 receptor agonist; retatrutide adds a third target, the glucagon receptor, whose arm adds energy expenditure (shown so far in mice). Tirzepatide is FDA-approved, as Mounjaro and Zepbound, and retatrutide isn’t approved yet. In their own trials, retatrutide’s top dose averaged about 25–28% weight loss at 80 weeks in phase 3, and tirzepatide’s 15 mg up to 22.5% at 72 weeks (SURMOUNT-1). ## Side by side | Compared | [Retatrutide](https://pepvault.app/peptides/retatrutide) | [Tirzepatide](https://pepvault.app/peptides/tirzepatide) | | --- | --- | --- | | Category | Metabolic & GLP-1 | Metabolic & GLP-1 | | Also known as | LY3437943 | Mounjaro, Zepbound, LY3298176 | | What it is | The first triple agonist to reach phase 3: it activates GLP-1, GIP and glucagon receptors at once, and the glucagon arm adds extra calorie burn (shown in mice). | The first dual GIP/GLP-1 receptor agonist: it activates two gut-hormone pathways at once, and in a head-to-head trial it produced more weight loss than semaglutide (20.2% vs 13.7% at 72 weeks). | | How it works | Triple GIP/GLP-1/glucagon receptor agonist. Produces large weight loss through appetite suppression and improved metabolic function; the glucagon arm adds energy expenditure, shown so far in mice. Its trials step the dose up every 4 weeks because GI side effects rise with the dose; in phase 2 they were milder with a 2 mg start than a 4 mg one. | Dual GIP/GLP-1 receptor agonist. Significantly reduces body weight through appetite suppression, slowed gastric emptying, and improved insulin sensitivity. Approved for T2DM and obesity management. | | Commonly reported | Appetite suppression even stronger than tirzepatide, GI side effects after each step-up, and a higher resting heart rate. Its top dose averaged about 25–28% weight loss at 80 weeks in phase 3; it isn't approved yet. | Very strong appetite suppression and meals ending early, with nausea or tiredness for a day or two after the injection, mostly after dose increases. FDA-approved for diabetes (Mounjaro) and for weight management and sleep apnea (Zepbound). | | Studied range | Research range: 1–12 mg, starting dose 2 mg. Studied in research — not a recommendation. | FDA label: 2.5–15 mg, starting dose 2.5 mg. | | How often | Weekly | Weekly | | Half-life | ~6 days (measured in early trials in people) | ~5 days (FDA label) | | Route | SubQ injection | SubQ injection | | Typical run | Phase 3 trials use continuous dosing. Community mirrors this — long-term with slow titration. | FDA-approved for ongoing use. Titrate slowly upward. Community maintains on minimum effective dose. | | Evidence | Established: clinical trials or FDA-approved use exists | Established: clinical trials or FDA-approved use exists | | Common side effects | Nausea, vomiting, diarrhea, constipation, decreased appetite, fatigue, abdominal pain | Nausea, diarrhea, vomiting, constipation, abdominal pain, decreased appetite, fatigue | Typical run: Community practice — opinions vary. Not a clinical recommendation. ## Week by week Each entry’s cards by day window, as the compound pages show them. Day 1 is the day you start it. ### Retatrutide - Day 1–28 · 2 mg Triple-agonist is kicking in - Day 29–84 · 4 mg Dose-response steepens - Day 60+ · 9 mg Watch for dysesthesia at higher doses - Day 84+ This is a maintenance medication, not a course - Day 85–168 · 8 mg Higher steps: strong satiety - Day 169–336 No plateau yet at week 48 - Day 337–476 Phase 3 territory: the headline numbers [Every card for retatrutide, with its sources](https://pepvault.app/peptides/retatrutide#weeks) ### Tirzepatide - Day 1–28 · 2.5 mg Getting your gut acclimated - Day 29–56 · 5 mg First therapeutic dose — weight drops - Day 57–112 · 7.5 mg Dual agonism in full effect - Day 113–168 · 12.5 mg Max titration reached - Day 169–504 Weeks 24 to 72: where most people plateau - Day 365+ A maintenance medication, not a course [Every card for tirzepatide, with its sources](https://pepvault.app/peptides/tirzepatide#weeks) ## Questions people ask ### How long do retatrutide and tirzepatide last? The half-life of retatrutide is ~6 days (measured in early trials in people). The half-life of tirzepatide is ~5 days (FDA label). ### How often are retatrutide and tirzepatide taken? Retatrutide: weekly. Route: SubQ injection. Tirzepatide: weekly. Route: SubQ injection. ### How are retatrutide and tirzepatide dosed in research? The research range for retatrutide is 1–12 mg, with a 2 mg starting dose. Studied in research — not a recommendation. The FDA label range for tirzepatide is 2.5–15 mg, with a 2.5 mg starting dose. ### What are the common side effects of retatrutide and tirzepatide? For retatrutide, the library lists: nausea, vomiting, diarrhea, constipation, decreased appetite, fatigue, abdominal pain. For tirzepatide: nausea, diarrhea, vomiting, constipation, abdominal pain, decreased appetite, fatigue. ## Each one in full - [Retatrutide: dosage, half-life & reference guide](https://pepvault.app/peptides/retatrutide) - [Tirzepatide: dosage, half-life & reference guide](https://pepvault.app/peptides/tirzepatide) - [Retatrutide dose guide](https://pepvault.app/lab/dosage/retatrutide) - [Tirzepatide dose guide](https://pepvault.app/lab/dosage/tirzepatide) PepVault for iPhone ## Track either one in PepVault Log every dose of retatrutide or tirzepatide, with reminders on your schedule. 7 days free on the yearly plan for new subscribers. [Download on the App Store](https://apps.apple.com/app/apple-store/id6779318649?pt=129020030&ct=compound-vs-band&mt=8) [Explore the live demo](https://pepvault.app/login) ## More comparisons - [All peptide comparisons](https://pepvault.app/peptides/compare) - [Semaglutide vs Tirzepatide](https://pepvault.app/peptides/compare/semaglutide-vs-tirzepatide) - [Retatrutide vs Semaglutide](https://pepvault.app/peptides/compare/retatrutide-vs-semaglutide) - [Mazdutide vs Tirzepatide](https://pepvault.app/peptides/compare/mazdutide-vs-tirzepatide) - [Survodutide vs Retatrutide](https://pepvault.app/peptides/compare/survodutide-vs-retatrutide) - [Orforglipron vs Semaglutide](https://pepvault.app/peptides/compare/orforglipron-vs-semaglutide) - [Cagrilintide vs Semaglutide](https://pepvault.app/peptides/compare/cagrilintide-vs-semaglutide) ## The library - [The peptide reference library](https://pepvault.app/peptides) - [Metabolic & GLP-1 peptides](https://pepvault.app/peptides#metabolic) ## Free tools - [The Dose Guide](https://pepvault.app/lab/dosage) - [Half-life & active level](https://pepvault.app/tools/peptide-half-life-calculator) - [Reconstitution calculator](https://pepvault.app/tools/reconstitution-calculator) - [GLP-1 titration planner](https://pepvault.app/tools/glp1-titration-calculator) PepVault is a research and tracking resource, not medical advice. Ranges are what studies used, never a dose for you. Brand names are trademarks of their owners; PepVault is independent of them. PepVault is a private research and tracking tool, not medical advice. The information here is reference material from published literature and community use — always verify it and discuss any protocol with a qualified clinician before changing it. Ozempic, Wegovy, Rybelsus, Mounjaro, Zepbound, Saxenda, Victoza and Trulicity are trademarks of their respective owners; PepVault is independent and not affiliated with or endorsed by any manufacturer. © 2026 PepVault