Built from the Semaglutide, Tirzepatide, Retatrutide research profiles · Profiles last updated October 1, 2026 · Reviewed by The Peptide Dispatch Editorial Team
This page compares Semaglutide, Tirzepatide and Retatrutide using only their research-profile data. Semaglutide (research stage: FDA-approved; half-life: About 7 days). It copies the gut hormone GLP-1, which is described as reducing appetite and slowing how fast the stomach empties. 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
| Semaglutide | Tirzepatide | Retatrutide | |
|---|---|---|---|
| Category | Metabolic | Metabolic | Metabolic |
| Research status | FDA-approved | FDA-approved | Phase 3 |
| Regulatory note (as of Sept 2026) | FDA-approved. Semaglutide is no longer on the FDA shortage list, so 503A/503B compounding of copies is restricted. Regulatory tracker → | 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 | ~7 days | ~5 days | ~6 days |
| Administration route | Subcutaneous injection | Subcutaneous injection | Subcutaneous injection |
| Dosing used in published research (not a recommendation) | Humans: 2.4 mg s.c. once weekly for 68 weeks, n=1961 (STEP 1, Wilding 2021). 0.5-1.0 mg s.c. weekly in healthy Japanese and Caucasian men (2018 PK trial). | 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-reported0.25–2.4 mg weekly, subcutaneous injection | 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 copies the gut hormone GLP-1, which is described as reducing appetite and slowing how fast the stomach empties. Proposed mechanism (GLP-1 receptor agonist pharmacology): GLP-1 receptor activation is described as reducing appetite and slowing gastric emptying. Its effect on body weight comes from clinical trials: in the STEP 1 phase 3 RCT in adults with overweight or obesity, once-weekly semaglutide 2.4 mg with lifestyle intervention produced a mean weight change of -14.9% at 68 weeks vs -2.4% with placebo (Wilding 2021). | 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). |
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| Profile description | GLP-1 receptor agonist FDA-approved for type 2 diabetes and chronic weight management. Brand names include Ozempic and Wegovy. Semaglutide is a prescription-only medication and must be obtained and used under the supervision of a licensed healthcare provider. | 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 | 2 |
For the sourced, dated status of every peptide in FDA's 2026 compounding actions, see the FDA peptide regulatory tracker.
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Educational content — not medical advice. Effects described are drawn from cited research in study subjects.