Tirzepatide: Dual GIP/GLP-1 receptor agonist
A dual GIP/GLP-1 receptor agonist that produced some of the largest weight-loss results in trials — FDA-approved by prescription; the 'research peptide' versions sold online are not the approved product.
What is Tirzepatide?
Tirzepatide is a dual agonist that activates both the GIP and GLP-1 receptors. In branded, FDA-approved forms it is prescribed for type 2 diabetes (Mounjaro) and chronic weight management (Zepbound). Its trial results are among the largest for any weight-loss medicine to date. As with other GLP-1 drugs, the unbranded 'research' tirzepatide sold by peptide vendors is not the FDA-approved product.
How Tirzepatide works (mechanism)
By engaging two incretin receptors — GIP and GLP-1 — tirzepatide enhances glucose-dependent insulin secretion, slows gastric emptying and reduces appetite. In the 72-week SURMOUNT-1 obesity trial, once-weekly tirzepatide produced mean weight reductions of roughly 15–21% depending on dose, versus about 3% for placebo [1].
Why it's studied / reported uses
Chronic weight management
SURMOUNT-1 demonstrated large, sustained weight loss with once-weekly tirzepatide in adults with obesity/overweight [1][2]. This is an FDA-approved indication (Zepbound).
Type 2 diabetes
As Mounjaro, tirzepatide is approved for glycemic control in type 2 diabetes, where the SURPASS trials showed strong reductions in HbA1c and body weight. Prescription use under medical supervision.
Dosing reported in studies
Route: subcutaneous
20-week titration to reach the top dose; used to limit GI side effects.
Route: subcutaneous
Not everyone escalates to 15 mg in trials.
Sources: Jastreboff et al. (2022) SURMOUNT-1 — N Engl J Med
A dual GIP/GLP-1 agonist. Prescription-only in approved forms. These figures reflect what studies or protocols reported — not a recommendation and not tailored to you.
Calculate a dose in the reconstitution calculator →Safety & side effects
Like other incretin drugs, the most common effects are gastrointestinal (nausea, diarrhoea, vomiting, constipation), are dose-related, and are the reason approved dosing titrates up over ~20 weeks. Approved labels carry a boxed warning about thyroid C-cell tumours (contraindicated with medullary thyroid carcinoma or MEN 2 history) and note pancreatitis and gallbladder risks. Prescription-only; use under a clinician.
Studies & references
- Tirzepatide once weekly for the treatment of obesity (SURMOUNT-1) — PubMed 35658024 (Jastreboff et al., NEJM 2022)
- SURMOUNT-1 trial registration — tirzepatide in obesity/overweight — ClinicalTrials.gov NCT04184622
Frequently asked questions
Is tirzepatide FDA-approved?
Yes — as Zepbound (weight management) and Mounjaro (type 2 diabetes). The unbranded 'research' tirzepatide sold by peptide vendors is not the approved product.
How is tirzepatide dosed?
Approved use titrates slowly — roughly 2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg once weekly, increasing about every 4 weeks (see the dosing section). This is not a recommendation; a prescriber sets the dose.
How does tirzepatide compare to semaglutide?
Tirzepatide acts on two receptors (GIP and GLP-1) versus one; head-to-head and trial data suggest somewhat larger average weight loss, but individual response varies. Both are prescription medicines.
What are the side effects?
Mostly gastrointestinal and dose-related, easing with slow titration. Serious risks and contraindications are on the approved label — discuss with a doctor.
⚠ Research & educational use only. This page is compiled from published research and does not constitute medical advice. Tirzepatide is FDA-approved as a prescription medicine in branded forms (Zepbound for weight management, Mounjaro for type 2 diabetes). Nothing here is a recommendation to use or a prescription. Safe use can only be determined by a licensed physician. Last updated 2026-07-06.