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Comparison

Ipamorelin vs Somatropin

Ipamorelin is gHRPs & ghrelin mimetics; Somatropin is IGF & growth factors. They are compared here because they are frequently considered against each other, not because they act alike.

On published evidence alone, Somatropin is the better documented of the two (regulator approved). That is a statement about the state of the literature, not a recommendation.

Ipamorelin Somatropin
Class GHRPs & ghrelin mimetics IGF & growth factors
Evidence Preliminary human Regulator approved
Human trials ~5 ~200
Half-life ~2 hours ~3-5 hours (subcutaneous)
Reported range 200-300 mcg 200 mcg - 1 mg
Frequency 1-3x daily, on an empty stomach Once daily, indication-dependent
Routes Subcutaneous Subcutaneous, Intramuscular
FDA approved No Yes
Research use only Yes No
Banned in sport Yes Yes
Studied for Growth hormone elevation, Recovery, Sleep quality, Body composition Growth hormone deficiency, Short stature syndromes, HIV wasting, Short bowel syndrome
Reported side effects Head rush on injection, Transient hunger, Water retention, Lethargy Peripheral oedema, Arthralgia, Carpal tunnel syndrome, Insulin resistance, Myalgia

Ipamorelin

Ipamorelin is a pentapeptide agonist at the growth hormone secretagogue receptor, the same receptor targeted by endogenous ghrelin. Unlike the earlier GHRPs it produces a GH pulse without meaningful elevation of adrenocorticotropic hormone, cortisol or prolactin, which is the basis of its reputation as the cleanest compound in the class. It is short-acting and is typically dosed alongside a GHRH analog to exploit the synergy between the two receptor pathways.

Somatropin

Somatropin is recombinant 191-amino-acid human growth hormone, identical in sequence to the pituitary hormone. It acts directly at growth hormone receptors in liver and peripheral tissue, driving hepatic IGF-1 production, lipolysis and nitrogen retention. Unlike the secretagogues it bypasses pituitary regulation entirely, which is both why it is more predictable and why it carries the greater risk of supraphysiologic exposure and negative feedback on endogenous production.

Ipamorelin vs Somatropin: common questions

What is the difference between Ipamorelin and Somatropin?

Ipamorelin is gHRPs & ghrelin mimetics and Somatropin is IGF & growth factors, so they act on different pathways. Ipamorelin: The most receptor-selective of the growth-hormone-releasing peptides, notable for leaving cortisol and prolactin essentially unchanged. Somatropin: Recombinant human growth hormone itself, the reference compound every secretagogue on this site is compared against.

Which has stronger evidence, Ipamorelin or Somatropin?

Somatropin has the stronger evidence base (regulator approved, about 200 human studies) compared with Ipamorelin (preliminary human).

Are Ipamorelin and Somatropin FDA approved?

Only Somatropin is FDA approved (Paediatric growth hormone deficiency; Adult growth hormone deficiency; Turner syndrome; Prader-Willi syndrome; Growth failure associated with chronic kidney disease; Children born small for gestational age without catch-up growth; Idiopathic short stature; SHOX deficiency; Noonan syndrome; HIV-associated wasting or cachexia (Serostim); Short bowel syndrome (Zorbtive, no longer marketed)). Ipamorelin is not approved for any indication.

References

Regulatory and primary sources

  1. PubChem compound record (CID 9831659) ↗ · structure, identifiers, synonyms
  2. WADA Prohibited List ↗ · current year
  3. FDA: Unapproved drugs and "research use only" products ↗ · regulatory status of non-approved products
  4. CAS Registry Number 170851-70-4 ↗ · chemical identity
  5. PubChem compound record (CID 137552069) ↗ · structure, identifiers, synonyms
  6. DailyMed: FDA-approved labeling for Somatropin ↗ · indications, dosing, warnings as approved
  7. FDA Drugs@FDA database ↗ · approval history
  8. CAS Registry Number 12629-01-5 ↗ · chemical identity

Published literature

  1. Mayfield CK, Bolia IK, Feingold CL, et al.. Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians.Am J Sports Med 2026.PubMed 41476424 · doi:10.1177/03635465251357593
  2. Rahman OF, Lee SJ, Seeds WA. 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
  3. Mendias CL, Awan TM. 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
  4. Renke G, Chinellato L. 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
  5. Coutinho LFD, DE Oliveira Neves LF, Camilo RP. A new era of doping? Use of peptide and peptide-analog drugs in recreational and professional sport and bodybuilding: a critical review.J Sports Med Phys Fitness 2026.PubMed 41880199 · doi:10.23736/S0022-4707.26.17773-1
  6. Gobburu JV, Agersø H, Jusko WJ, et al.. Pharmacokinetic-pharmacodynamic modeling of ipamorelin, a growth hormone releasing peptide, in human volunteers.Pharm Res 1999.PubMed 10496658 · doi:10.1023/a:1018955126402
  7. Beck DE, Sweeney WB, McCarter MD, et al.. Prospective, randomized, controlled, proof-of-concept study of the Ghrelin mimetic ipamorelin for the management of postoperative ileus in bowel resection patients.Int J Colorectal Dis 2014.PubMed 25331030 · doi:10.1007/s00384-014-2030-8
  8. Villegas Meza AD, Nocek M, Mitchell BC, et al.. Injectable Peptides in Sports Medicine: A Structured Narrative Review of Evidence, Safety, and Antidoping Implications.JBJS Rev 2026.PubMed 42160466 · doi:10.2106/JBJS.RVW.26.00027
  9. Bidlingmaier M, Strasburger CJ. Growth hormone.Handb Exp Pharmacol 2010.PubMed 20020365 · doi:10.1007/978-3-540-79088-4_8
  10. Deal CL, Steelman J, Vlachopapadopoulou E, et al.. 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
  11. Bidlingmaier M, Wu Z, Strasburger CJ. Doping with growth hormone.J Pediatr Endocrinol Metab 2001.PubMed 11592563 · doi:10.1515/jpem-2001-0802
  12. Pfäffle R, Kiess W. GH and IGF-1 Replacement in Children.Handb Exp Pharmacol 2020.PubMed 31932988 · doi:10.1007/164_2019_337
  13. Wang K, Ye F, Wang DY, et al.. 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
  14. Thornton PS, Maniatis AK, Aghajanova E, et al.. 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
  15. Blunden C, Nasomyont N, Backeljauw P. Growth Hormone Therapy for Turner Syndrome.Pediatr Endocrinol Rev 2018.PubMed 30378785 · doi:10.17458/per.vol16.2018.bnb.ghtherapyturnersyndrome
  16. Goldsmith DR, Wagstaff AJ. 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

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.

Read this first This page compares published reference data. It is not medical advice and not a recommendation to use either compound. Several compounds documented on this site are not approved for human use.