§ Head-to-Head Comparison

Semaglutide vs Tirzepatide.

Clinical research comparison of Semaglutide vs Tirzepatide: STEP 1 & SURMOUNT-1 trial data, half-life, mechanisms, and side effects.

Weight Loss

Editor's Note

These weight-loss percentages come from SEPARATE trials of different durations (STEP 1: 68 weeks vs SURMOUNT-1: 72 weeks) and populations. No head-to-head randomized trial has directly compared these specific weight-loss figures. Tirzepatide’s ~20.9% is the treatment-regimen estimand; the efficacy estimand (which excludes dropouts) reports ~22.5% at the 15mg dose.

Quick Verdict

Tirzepatide achieved ~20.9% weight loss (SURMOUNT-1, 72wk) via dual GLP-1/GIP mechanisms. Semaglutide achieved ~14.9% (STEP 1, 68wk) but offers a longer real-world safety track record.

Side-by-Side Analysis

DimensionSemaglutideTirzepatide
MechanismGLP-1 receptor agonism mimics the incretin hormone to reduce appetite, slow gastric emptying, improve insulin sensitivity, and provide cardiovascular protection.Dual receptor agonism at GLP-1 and GIP receptors for synergistic appetite suppression, improved insulin sensitivity, and enhanced metabolic function.
Primary BenefitsFat loss, appetite control, cardiovascular benefitsWeight loss, body recomposition, glycemic control
Typical Dose250–250mcg2500–2500mcg
RouteSubQSubQ
Frequency1x/wk1x/wk
Half-Life168 hours120 hours
FDA StatusApprovedApproved
Evidence Gradevery-strongvery-strong
Key Studies20+ indexed20+ indexed
Weight Loss (Trial)
~14.9%
STEP 1 · 68 weeks · n=1,961
Phase 3 · PMID 33567185
~20.9%
SURMOUNT-1 · 72 weeks · n=2,539
Phase 3 · PMID 35658024
Treatment-regimen estimand; efficacy estimand reports ~22.5% at 15mg
Lowest Price$47.99 / 5mg via Amino Club$69.99 / 5mg via Amino Club

Which one should you choose?

**Data Context & Limitations:** The clinical figures cited below are drawn from separate clinical trials—the STEP 1 trial (68 weeks) and SURMOUNT-1 trial (72 weeks). There are no direct, head-to-head trials comparing these specific compounds. Weight loss percentages are therefore not perfectly comparable due to differing trial durations, populations, and designs. **The Verdict:** Tirzepatide (Zepbound/Mounjaro) has demonstrated a higher ceiling for weight reduction in its clinical trials compared to semaglutide (Wegovy/Ozempic), driven by its dual agonism of both GLP-1 and GIP receptors. In the 72-week SURMOUNT-1 trial, tirzepatide reached up to a ~20.9% average body weight reduction (treatment-regimen estimand; note some sources cite the 22.5% efficacy estimand), while semaglutide achieved ~14.9% over 68 weeks in the STEP 1 trial. However, semaglutide has the longest track record and broadest regulatory approval. For research purposes, semaglutide is often a reliable starting point due to its extensive long-term data. Tirzepatide is typically investigated when maximizing metabolic response or total weight loss is the primary objective. *This information is provided for research and educational purposes only and does not constitute medical or prescribing advice.*

Who Should Choose Semaglutide?

Choose Semaglutide if you:

  • Are new to GLP-1 agonists and want the most proven starting point
  • Have cardiovascular disease concerns (SELECT trial: 20% CV event reduction)
  • Want a more affordable research option with longer safety data
  • Are researching T2DM or pre-diabetic metabolic states

Who Should Choose Tirzepatide?

Choose Tirzepatide if you:

  • Want maximum weight loss efficacy in a single agent
  • Have experienced intolerable nausea on Semaglutide (Tirzepatide is often better tolerated)
  • Have plateaued on a GLP-1 and need a mechanistic upgrade
  • Are researching insulin resistance alongside obesity

Can you stack Semaglutide + Tirzepatide?

Do NOT stack Semaglutide and Tirzepatide — they share the GLP-1 receptor. Additive GLP-1 stimulation creates severe nausea, hypoglycemia risk, and potential cardiovascular complications. They are competing agents, not complements.

Vendor Pricing

· Affiliate links · Prices verified 2026

Semaglutide

2 vendors
Amino Club Best Value
5mg vial · $9.60/mg
$47.99Buy
Limitless Life
5mg vial · $11.60/mg
$58.00Buy
Full vendor comparison for Semaglutide

Tirzepatide

2 vendors
Amino Club Best Value
5mg vial · $14.00/mg
$69.99Buy
Limitless Life
5mg vial · $16.00/mg
$80.00Buy
Full vendor comparison for Tirzepatide

Affiliate disclosure: PeptiDex may earn a commission from purchases via vendor links at no extra cost to you. See our methodology.

Frequently Asked Questions

Tirzepatide consistently produces greater weight loss (~21% body weight at maximum dose) vs Semaglutide (~15%) in clinical trials. The SURMOUNT vs STEP trial data confirms this difference.

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Research Use Only — Not Medical Advice

This comparison is provided for educational and research purposes only. It does not constitute medical, prescribing, or treatment advice. Clinical data cited here is sourced from published peer-reviewed trials and FDA labels. Consult a qualified healthcare professional before making any decisions about medications or research compounds. PeptiDex is an informational resource and does not sell pharmaceutical products.