Dual GIP/GLP-1 receptor agonist developed by Eli Lilly, approved for type 2 diabetes (Mounjaro®) and chronic weight management (Zepbound®).
Last Updated: May 2026
Tirzepatide is a 39-amino-acid synthetic peptide and the first FDA-approved dual GIP/GLP-1 receptor agonist, marketed by Eli Lilly as Mounjaro for type 2 diabetes and Zepbound for chronic weight management. It was approved for diabetes in May 2022 and for obesity in November 2023. Research-grade tirzepatide is also sold by third-party laboratories for laboratory use only — that material is not the FDA-approved prescription product and carries no pharmacy-grade quality controls.
Tirzepatide activates both GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1) receptors with a single 39-amino-acid molecule, producing larger insulin-sensitizing and weight-loss effects than GLP-1-only agonists. The dual mechanism increases insulin secretion glucose-dependently, slows gastric emptying, suppresses appetite via central GLP-1 pathways, and adds GIP-mediated effects on adipocyte function. The molecule is bound to a C20 fatty diacid side chain, extending half-life to approximately 5 days and enabling once-weekly subcutaneous dosing. Evidence level: Human RCT (multiple Phase 3 trials in SURPASS and SURMOUNT programs).
In SURMOUNT-1 (n=2,539), tirzepatide produced an average weight loss of 22.5% at the 15 mg dose over 72 weeks in adults with obesity without type 2 diabetes. Lower doses (5 mg, 10 mg) produced 16.0% and 21.4% weight loss respectively versus 2.4% for placebo. In SURPASS trials for type 2 diabetes, tirzepatide reduced HbA1c by up to 2.4 percentage points and outperformed semaglutide head-to-head in SURPASS-2. For cross-compound context, see our semaglutide vs tirzepatide comparison guide. Evidence level: Human RCT (Phase 3).
Tirzepatide sits between semaglutide (single-receptor) and retatrutide (triple-receptor) on both mechanism complexity and weight-loss efficacy. Tirzepatide's 22.5% SURMOUNT-1 result exceeded semaglutide's 14.9% in STEP 1, and retatrutide's TRIUMPH-4 result of 28.7% exceeded tirzepatide's. Tirzepatide is the only one of the three currently FDA-approved for obesity in the United States.
| Compound | Mechanism | Phase 3 weight loss | Regulatory status |
|---|---|---|---|
| Retatrutide | GLP-1 + GIP + glucagon (triple) | 28.7% — TRIUMPH-4, 68 wks | Investigational |
| Tirzepatide | GLP-1 + GIP (dual) | 22.5% — SURMOUNT-1, 72 wks | FDA-approved (Mounjaro/Zepbound) |
| Semaglutide | GLP-1 (single) | 14.9% — STEP 1, 68 wks | FDA-approved (Ozempic/Wegovy) |
The most common tirzepatide side effects in SURMOUNT-1 were gastrointestinal — nausea (33%), diarrhea (19%), vomiting (12%), and constipation (12%) — typically mild-to-moderate and concentrated in the dose-escalation phase. Tirzepatide hair loss has emerged as a notable patient-reported side effect, characterized in the SURMOUNT data and analyzed in detail in our tirzepatide side effects guide. Discontinuation rates due to adverse events ranged from 4.3% to 7.1% across doses. Evidence level: Human RCT (Phase 3).
Tirzepatide is FDA-approved as Mounjaro (type 2 diabetes, May 2022) and Zepbound (chronic weight management, November 2023), with EMA approval following for both indications. It is available by prescription through licensed pharmacies. Research-grade tirzepatide sold by third-party laboratories is not the FDA-approved prescription product — that material is supplied for research use only and does not carry pharmacy-grade quality controls. For the prescription-vs-research-grade legal distinction, see our peptide regulatory status by country guide.
Because the FDA approval applies to Lilly's pharmacy-distributed Mounjaro and Zepbound — not to research-grade tirzepatide sold by third-party labs, which is a separate supply chain with its own quality risks. The active ingredient may be the same molecule, but research-grade material is subject to wider purity variance, occasional underdosing, and inconsistent endotoxin control. Independent HPLC purity testing and mass spectrometry identity confirmation (expected MW 4,813.5 Da) are the only meaningful purity signals a research-grade vendor can provide. Learn how to interpret these in our how-to-test-peptides hub and reading peptide lab test results guide.
Peptigrity purchases tirzepatide vials anonymously at standard customer pricing, sends them to ISO-accredited third-party labs for HPLC and mass spectrometry analysis, and publishes the unedited certificate of analysis. The lab test table above this section shows the full cross-shop dataset, sortable by date, purity, and labeled-vs-tested quantity. Tests are sourced from named labs including Freedom Diagnostics, Janoshik Analytical, Chromate, Vanguard Laboratory, and Trust Pointe Analytics. Our trust score methodology weights reviews (50%) and lab purity (50%) — full detail in how we calculate trust scores.
The only reliable purity signal is an independent third-party HPLC certificate of analysis from a lab the vendor does not own or pay — not a vendor-published COA on vendor letterhead. Peptigrity publishes independent tirzepatide test results from ISO-accredited labs in the table above. For COA interpretation, see red flags in peptide certificates of analysis.
Research-grade tirzepatide is legal to purchase as a research chemical for laboratory use in most jurisdictions, but it is not approved for human consumption and is not the FDA-approved prescription product. The FDA-approved versions (Mounjaro, Zepbound) require a prescription. For the legal distinction between research-grade and pharmacy-grade supply, see our peptide legal status guide.
Compounding pharmacy access to tirzepatide depends on FDA shortage status and 503A/503B regulations, both of which have shifted during 2024–2025. When tirzepatide is on the FDA shortage list, 503A pharmacies may compound it; when off the list, that pathway closes. For the current state of compounding pharmacy access and FDA determinations, see FDA peptide regulation 2025–2026: the complete timeline.
Research-grade tirzepatide is manufactured by third-party laboratories without the pharmaceutical-grade overhead (FDA inspections, full GMP compliance, branded packaging, distribution chain markups) that prices Mounjaro/Zepbound. It also doesn't carry the regulatory protection or quality guarantees those products do. Current research-grade market range is broken down in how much do peptides cost.
No. Peptigrity is an independent review platform, not a medical authority — and research-grade tirzepatide is not approved for human consumption. The doses studied in SURMOUNT and SURPASS (2.5 mg through 15 mg weekly, with mandatory titration) were administered under clinical supervision. Anyone considering tirzepatide should consult a licensed physician about the prescription product.
Retatrutide has produced larger percent weight loss than tirzepatide in matched-duration Phase 3 trials, but retatrutide is not FDA-approved while tirzepatide is. Retatrutide's TRIUMPH-4 result of 28.7% at 68 weeks exceeds tirzepatide's SURMOUNT-1 result of 22.5% at 72 weeks. No head-to-head Phase 3 data exists yet. Full mechanism breakdown is in our retatrutide triple-agonist science guide.
This section is for educational and informational purposes only and does not constitute medical advice. Research-grade tirzepatide sold for laboratory use is not the FDA-approved prescription product (Mounjaro, Zepbound). Always consult a qualified healthcare provider before using any peptide or research compound. Peptigrity is an independent review platform and does not sell, endorse, or recommend specific products or vendors.
Real protocols and questions from members — independent of vendors, never sponsored.
Sign in to ask a question.
Every submitted test helps the community verify purity across brands. Free, fast, independent.