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/ comparison

Tirzepatide
vs
Retatrutide (GLP-3)

Side-by-side comparison of mechanism, research, dosing, side effects, and pricing.

peptide

Tirzepatide

Dual receptor agonist. Outperforms semaglutide in head-to-head trials.

Cheapest
$85.93
5mg at Ascension Peptides
See Tirzepatide →
peptide

Retatrutide (GLP-3)

Next-generation triple receptor agonist. Phase 3 clinical research underway.

Cheapest
$69.51
5mg at Throne
See Retatrutide (GLP-3) →
/ research scoring

Research base

Tirzepatide
Research Maturity★★★★★
Evidence Strength★★★★★

FDA approved. Phase 3 trials show superior metabolic effects vs single-receptor agonists.

Retatrutide (GLP-3)
Research Maturity★★★★☆
Evidence Strength★★★★☆

Phase 2 human trials demonstrate exceptional metabolic effects. 99%+ purity verified across batches in research-grade product.

/ mechanism

How they work

Tirzepatide

Activates both GLP-1 and GIP receptors. Dual-pathway stimulation.

Retatrutide (GLP-3)

Simultaneously activates GLP-1, GIP, and glucagon receptors. Triple-receptor synergy for metabolic optimization.

/ research dosing

Protocols compared

Tirzepatide
Range: 2.5 → 5 → 7.5 → 10 → 12.5 → 15 mg/week (FDA titration)
Frequency: Once weekly subcutaneous
Route: Subcutaneous abdomen, thigh, or upper arm
Standard FDA titration for Mounjaro/Zepbound. Same molecule, same dosing ladder. Each step held 4 weeks minimum. If missing dose: take if >72 hours until next dose; otherwise skip. Dual GLP-1/GIP agonist — typically better GI tolerance than retatrutide at equivalent weight-loss efficacy.
Retatrutide (GLP-3)
Range: 2 → 4 → 6 → 8 → 12 mg/week (titration ladder)
Frequency: Once weekly subcutaneous
Route: Subcutaneous abdomen, thigh, or upper arm
Phase 2 trials titrated 2 → 4 → 8 → 12 mg/week over 24 weeks. GI side effects (nausea, occasional vomiting) peak with each dose increase. Heart rate elevation ~3-7 bpm at higher doses. Slow titration is essential — rapid escalation causes significant GI distress.
/ side effects & timeline

What to expect

Tirzepatide
Side effects

Common: GI adjustment. Well-tolerated overall.

Timeline

Effects within 2-4 weeks

Retatrutide (GLP-3)
Side effects

Common: GI adjustment, appetite reduction (intended effect). Well-tolerated in clinical trials.

Timeline

Effects observed within 2-4 weeks; full metabolic adaptation 12+ weeks

/ pricing

Price comparison

Tirzepatide
Lowest price$85.93 (5mg)
Min $/mg$7.90/mg
Avg $/mg$20.50/mg
Max $/mg$45.19/mg
Retatrutide (GLP-3)
Lowest price$69.51 (5mg)
Min $/mg$5.73/mg
Avg $/mg$17.16/mg
Max $/mg$36.24/mg
/ which to pick

The honest verdict

Pick Tirzepatide if: Highly effective alone. Dual-agonist mechanism is its key feature.

Pick Retatrutide (GLP-3) if: Highly effective standalone compound. Triple-receptor agonism is its primary differentiator.

Why not both? Some researchers run them together. Check our Interaction Matrix to see if these compounds synergize or work independently.

FOR RESEARCH USE ONLY. Both compounds are intended for laboratory research and not for human consumption.