Retatrutide vs Tesamorelin
A detailed comparison to help you understand the differences and choose the right peptide for your research goals.
Retatrutide
Retatrutide (LY3437943) is a first-in-class triple agonist peptide targeting GIP, GLP-1, and glucagon receptors simultaneously. Developed by Eli Lilly, it is currently in Phase 3 clinical trials and has demonstrated the highest weight loss of any obesity medication to date — up to 28.7% body weight reduction at 48 weeks. The triple-receptor mechanism represents the next evolution beyond dual agonists like tirzepatide.
Full details →Tesamorelin
Tesamorelin is a synthetic analog of growth hormone-releasing hormone (GHRH). It is FDA-approved under the brand name Egrifta for reducing excess abdominal fat in HIV-infected patients with lipodystrophy.
Full details →Side-by-Side Comparison
| Aspect | Retatrutide | Tesamorelin |
|---|---|---|
| Dose Range | 4 mg–12 mg | 2 mg |
| Frequency | Less than daily | 1x daily |
| Cycle Length | — | 8–52 weeks |
| Route | subcutaneous | subcutaneous |
| Mechanism | Retatrutide is a synthetic peptide that activates three incretin/metabolic hormone receptors: (1) GLP-1 receptor — appetite suppression, insulin secretion, delayed gastric emptying, (2) GIP receptor — enhanced insulin sensitivity, improved fat metabolism, (3) Glucagon receptor — increased energy expenditure, hepatic fat mobilization, thermogenesis. The glucagon receptor component is the key differentiator, adding an energy-expenditure mechanism absent from GLP-1 and dual GIP/GLP-1 agonists. The molecule uses a C20 fatty diacid for albumin binding, enabling once-weekly dosing. | Stimulates the pituitary gland to produce and release growth hormone by binding to GHRH receptors. Increases IGF-1 levels which promotes lipolysis and reduces visceral adipose tissue. |
| Typical Dosage | Phase 2 trial doses: 0.5 mg, 4 mg, 8 mg, and 12 mg weekly. The 12 mg dose produced maximum weight loss (28.7%). Phase 3 trials are evaluating doses up to 12 mg. Dose escalation schedule similar to other GLP-1s (start low, increase every 4 weeks). Final approved dosing not yet established — Phase 3 trials ongoing. | FDA-approved dose: 2mg administered subcutaneously once daily. Research protocols may use various dosing schedules. |
| Administration | Subcutaneous injection, once weekly. Phase 3 trials use pre-filled single-dose pens. Not yet commercially available — estimated FDA approval ~2027-2028. | Subcutaneous injection into the abdomen. Rotate injection sites. Best administered at the same time daily, preferably in the evening. |
| Side Effects | Phase 2 data: nausea (up to 25%), diarrhea (up to 22%), vomiting (up to 15%), constipation, decreased appetite. GI side effects were dose-dependent and generally mild-to-moderate. Lower rates of nausea compared to semaglutide, potentially due to GIP component. Increased heart rate observed at higher doses. | Common side effects include injection site reactions (erythema, pruritus), joint pain, peripheral edema, and muscle pain. May cause elevated blood glucose. |
| Best For |
Key Differences
Unique to Retatrutide:
Unique to Tesamorelin:
Key Studies
Retatrutide
- Retatrutide in type 2 diabetes mellitus and obesity: an overview.
Expert review of clinical pharmacology, 2026
- Retatrutide for the treatment of obesity, obstructive sleep apnea and knee osteoarthritis: Rationale and design of the TRIUMPH registrational clinical trials.
Diabetes, obesity & metabolism, 2026
- Rationale, design and baseline characteristics of the TRANSCEND-CKD trial of retatrutide in patients with chronic kidney disease.
Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association, 2026
Tesamorelin
- Tesamorelin as an Adjunct to Exercise for Improving Physical Function in HIV (TRIUMPH): a clinical trial protocol.
BMJ open, 2026
- Effects of Tesamorelin on Neurocognitive Impairment in Persons With HIV and Abdominal Obesity.
The Journal of infectious diseases, 2025
- Efficacy and safety of tesamorelin in people with HIV on integrase inhibitors.
AIDS (London, England), 2024
Ready to Learn More?
Looking for trusted sources?