Last updated: March 2026
The two dominant GLP-1 agonists, head to head. Tirzepatide (Mounjaro/Zepbound) adds GIP receptor activation to GLP-1 — and the clinical data shows it. Here's what SURMOUNT and STEP trials actually found.
| Feature | Tirzepatide | Semaglutide |
|---|---|---|
| Mechanism | Dual GIP + GLP-1 agonist | GLP-1 agonist only |
| Brand Names | Mounjaro (T2D), Zepbound (obesity) | Ozempic (T2D), Wegovy (obesity) |
| Manufacturer | Eli Lilly | Novo Nordisk |
| Max Weight Loss | ~22.5% (SURMOUNT-1, 15mg) | ~15.8% (STEP 1, 2.4mg) |
| A1C Reduction | Up to −2.58% (SURPASS-1) | Up to −1.86% (SUSTAIN-1) |
| Dosing Frequency | Once weekly (SubQ) | Once weekly (SubQ) |
| Dose Range | 2.5mg → 5 → 7.5 → 10 → 12.5 → 15mg | 0.25mg → 0.5 → 1 → 1.7 → 2.4mg |
| Titration Steps | 6 doses | 5 doses |
| FDA Approval (T2D) | May 2022 | December 2017 |
| FDA Approval (Obesity) | November 2023 (Zepbound) | June 2021 (Wegovy) |
| List Price/Month | ~$1,060 | ~$1,350 |
| Oral Form | Not yet approved | Rybelsus (oral, T2D only) |
Tirzepatide's dual mechanism targets both GIP and GLP-1 pathways. GIP (glucose-dependent insulinotropic polypeptide) amplifies insulin response and may independently reduce appetite through central nervous system signaling.
A single molecule that activates both GIP and GLP-1 receptors simultaneously. GIP receptor activation enhances insulin secretion, improves lipid metabolism, and appears to amplify GLP-1's appetite suppression through complementary CNS pathways. The result: greater weight loss and glycemic control than either target alone.
A modified GLP-1 analog with a fatty acid side chain enabling once-weekly dosing. Mimics natural GLP-1 to stimulate insulin secretion, suppress glucagon, slow gastric emptying, and reduce appetite via hypothalamic signaling. Highly effective — but targets only one of the two incretin pathways.
Both drugs use a slow titration to minimize GI side effects. Tirzepatide has more dose steps, allowing finer adjustment. Both are once-weekly subcutaneous injections.
Both drugs share the same primary side effects: nausea, diarrhea, vomiting, and constipation. Rates are broadly similar between classes, with most events being mild-to-moderate and decreasing over time. Data from SURMOUNT-1 (tirzepatide) and STEP 1 (semaglutide).
Note on GI side effects: Most are transient and occur primarily during dose escalation. Slow titration significantly reduces severity. In SURMOUNT-1, only 4.3% of tirzepatide patients discontinued due to adverse events vs 2.6% for placebo. STEP 1 reported 7.0% discontinuation for semaglutide vs 3.1% for placebo.
Both drugs carry premium pricing without insurance. Manufacturer coupons and savings cards exist but vary. Compounded versions are available but exist in a legal gray area — FDA has pushed back on compounded GLP-1s.
Compounded GLP-1s: Compounding pharmacies have offered tirzepatide and semaglutide at significantly lower cost ($200–400/month). However, the FDA has periodically challenged the shortage status that enables compounding. Both branded drugs remain expensive without insurance, and coverage varies widely by plan and indication (T2D vs obesity).
Both are highly effective GLP-1 class drugs. The choice depends on your specific situation, insurance coverage, and treatment goals. Always work with a physician.
Dosing schedules, interaction warnings, and cycle protocols for 50+ compounds — all in one place.
This page is for educational and informational purposes only. It is not medical advice. Tirzepatide (Mounjaro/Zepbound) and semaglutide (Ozempic/Wegovy) are FDA-approved prescription medications. They require a prescription and should only be used under medical supervision. Weight loss percentages cited reflect clinical trial averages — individual results vary significantly. Cross-trial comparisons have inherent limitations due to different study populations and designs. Always consult a qualified healthcare provider before starting, stopping, or switching GLP-1 medications. MeetPeptide does not sell medications or endorse their use without proper medical oversight.