The best peptides for muscle growth, and what the evidence actually supports
The GH-axis compounds dominate this category, and the honest summary is that they raise growth hormone and IGF-1 reliably while the muscle-building outcome data in healthy adults is thin. The compounds below are ranked on how well their mechanism is documented in humans.
Quick answer
| # | Compound | Class | Evidence | Reported range | Status |
|---|---|---|---|---|---|
| 1 | Somatropin | IGF & growth factors | Regulator approved | 200 mcg - 1 mg | Prescription |
| 2 | Tesamorelin | GHRH analogs | Regulator approved | 1-2 mg | Prescription |
| 3 | MK-677Not a peptide | GHRPs & ghrelin mimetics | Clinical trials | 10-25 mg | Research only |
| 4 | Ipamorelin | GHRPs & ghrelin mimetics | Preliminary human | 200-300 mcg | Research only |
| 5 | CJC-1295 | GHRH analogs | Preliminary human | 100-300 mcg | Research only |
| 6 | IGF-1 LR3 | IGF & growth factors | Animal models only | 20-50 mcg | Research only |
The ranking
Recombinant growth hormone is the reference compound and the only one here with a large approved clinical history. It is also the one with the most documented downside at supraphysiologic doses, and distributing it for non-approved use is a federal offence.
An approved GHRH analog with the strongest trial base of any secretagogue. It raises IGF-1 and preserves pituitary feedback. The approval is for visceral fat, not muscle, so the muscle-growth use is an inference from mechanism.
Oral, long-acting, and with more than twenty human studies showing sustained GH and IGF-1 elevation and increases in lean mass in older adults. Not a peptide. The costs are appetite and a consistent hit to insulin sensitivity.
Material for this compound is sold for laboratory research only. It is not manufactured, tested or labelled for human administration.
The most selective GHRP, with no meaningful cortisol or prolactin spillover. Human data is limited to small studies, which is why it ranks below MK-677 despite being the better-tolerated compound in practice.
Material for this compound is sold for laboratory research only. It is not manufactured, tested or labelled for human administration.
The non-DAC form, paired with ipamorelin, is the standard GHRH + GHRP stack. The synergy is real pharmacology. The human evidence is four small studies. FDA has placed it in Category 2, so compounding pharmacies cannot prepare it.
Powerful in cell culture and animal models and entirely without human trial data. It is sold as a cell-culture reagent. Hypoglycaemia is the acute risk; mitogenic activity is the long-term one. It ranks last because it ranks on nothing.
Material for this compound is sold for laboratory research only. It is not manufactured, tested or labelled for human administration.
What we left out, and why
- Follistatin-344
- The dramatic animal results come from gene therapy, not injection. The injectable protein is cleared in minutes.
- ACE-031
- Development was discontinued over vascular side effects in a trial population.
- YK-11
- A steroidal compound, not a peptide, with hepatotoxicity risk and zero human data.
Head-to-head comparisons
References for the compounds in this guide
- Growth hormone.Handb Exp Pharmacol 2010.PubMed 20020365 · doi:10.1007/978-3-540-79088-4_8
- Efficacy and Safety of Weekly Somatrogon vs Daily Somatropin in Children With Growth Hormone Deficiency: A Phase 3 Study.J Clin Endocrinol Metab 2022.PubMed 35405011 · doi:10.1210/clinem/dgac220
- Doping with growth hormone.J Pediatr Endocrinol Metab 2001.PubMed 11592563 · doi:10.1515/jpem-2001-0802
- GH and IGF-1 Replacement in Children.Handb Exp Pharmacol 2020.PubMed 31932988 · doi:10.1007/164_2019_337
- Aromatase inhibitors for short stature in male children and adolescents treated with growth hormone: a meta-analysis of randomized controlled trials.BMC Pediatr 2024.PubMed 39696162 · doi:10.1186/s12887-024-05301-0
- Weekly Lonapegsomatropin in Treatment-Naïve Children With Growth Hormone Deficiency: The Phase 3 heiGHt Trial.J Clin Endocrinol Metab 2021.PubMed 34272849 · doi:10.1210/clinem/dgab529
- Growth Hormone Therapy for Turner Syndrome.Pediatr Endocrinol Rev 2018.PubMed 30378785 · doi:10.17458/per.vol16.2018.bnb.ghtherapyturnersyndrome
- Mammalian cell-derived somatropin : a review of its use in the management of HIV-associated wasting.Drugs 2006.PubMed 16526830 · doi:10.2165/00003495-200666030-00014
- Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions.J Am Acad Orthop Surg Glob Res Rev 2026.PubMed 41490200 · doi:10.5435/JAAOSGlobal-D-25-00236
- Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians.Am J Sports Med 2026.PubMed 41476424 · doi:10.1177/03635465251357593
- Body composition, hepatic fat, metabolic, and safety outcomes of Tesamorelin, a GHRH analogue, in HIV-associated lipodystrophy: A meta-analysis of randomized controlled trials.Obes Res Clin Pract 2026.PubMed 41545261 · doi:10.1016/j.orcp.2026.01.002
- Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance.Sports Med 2026.PubMed 41966639 · doi:10.1007/s40279-026-02437-0
- Tesamorelin: a review of its use in the management of HIV-associated lipodystrophy.Drugs 2011.PubMed 21668043 · doi:10.2165/11202240-000000000-00000
- Tesamorelin: a growth hormone-releasing factor analogue for HIV-associated lipodystrophy.Ann Pharmacother 2012.PubMed 22298602 · doi:10.1345/aph.1Q629
- Therapeutic Peptides in Aesthetic, Metabolic and Endocrine Conditions: Effects, Safety, Clinical Applications, and Future Perspectives.Int J Mol Sci 2026.PubMed 42123471 · doi:10.3390/ijms27093890
- CROI 2024: Neuropsychiatric Complications in People With HIV.Top Antivir Med 2024.PubMed 39746672
- Growth hormone-releasing peptides.Eur J Endocrinol 1997.PubMed 9186261 · doi:10.1530/eje.0.1360445
- MK-677, an orally active growth hormone secretagogue, reverses diet-induced catabolism.J Clin Endocrinol Metab 1998.PubMed 9467534 · doi:10.1210/jcem.83.2.4551
- The Safety and Efficacy of Growth Hormone Secretagogues.Sex Med Rev 2018.PubMed 28400207 · doi:10.1016/j.sxmr.2017.02.004
- Growth hormone-releasing peptides and their analogs.Front Neuroendocrinol 1998.PubMed 9465289 · doi:10.1006/frne.1997.0158
- New directions in growth hormone treatment in children.Pediatr Endocrinol Diabetes Metab 2025.PubMed 41693185 · doi:10.5114/pedm.2025.158544
- Growth hormone-releasing peptides and the cardiovascular system.Ann Endocrinol (Paris) 2000.PubMed 10790589
- Regulation of ghrelin secretion and action.Endocrine 2003.PubMed 14610293 · doi:10.1385/ENDO:22:1:5
- Ghrelin receptor (GHS-R1A) agonists show potential as interventive agents during aging.Ann N Y Acad Sci 2007.PubMed 18056963 · doi:10.1196/annals.1404.023
Literature retrieved from PubMed on October 16, 2026, favouring human studies and reviews. Numbered markers in the text show which paper supports which statement; uncited entries are background reading.