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Comparison

Melanotan II vs Setmelanotide

Both are melanocortins, so the meaningful differences are in kinetics, evidence and regulatory status.

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

Melanotan II Setmelanotide
Class Melanocortins Melanocortins
Evidence Preliminary human Regulator approved
Human trials ~6 ~10
Half-life ~1-2 hours ~11 hours
Reported range 250 mcg - 1 mg 1-3 mg
Frequency Daily loading then 2-3x weekly maintenance Once daily
Routes Subcutaneous Subcutaneous
FDA approved No Yes
Research use only Yes No
Banned in sport No No
Studied for Tanning, Appetite suppression, Erectile function POMC, PCSK1 and LEPR deficiency obesity, Bardet-Biedl syndrome
Reported side effects Nausea, Facial flushing, Spontaneous erections, Darkening of moles, Appetite loss, Lethargy Injection-site reactions, Skin hyperpigmentation, Nausea, Spontaneous penile erection, Depression

Melanotan II

Melanotan II is a cyclic lactam analog of alpha-melanocyte-stimulating hormone that activates melanocortin receptors non-selectively, including MC1R, MC3R and MC4R. MC1R activation drives melanogenesis and tanning; MC4R activation produces the appetite suppression and the erectile effects that led to the development of the selective derivative bremelanotide. Non-selectivity is precisely the problem: users cannot obtain one effect without the others, and health agencies in several countries have issued warnings about unregulated supply and about melanoma risk from darkening existing naevi.

Setmelanotide

Setmelanotide is a cyclic peptide agonist selective for the melanocortin-4 receptor, the terminal node of the leptin-melanocortin pathway that regulates hunger and energy balance. In patients whose obesity stems from defects upstream of MC4R, such as POMC, PCSK1 or LEPR deficiency, it restores signalling through the intact receptor and produces substantial weight loss and reduced hyperphagia. It is ineffective where the MC4R itself is fully non-functional, which is why genetic confirmation gates its use.

Melanotan II vs Setmelanotide: common questions

What is the difference between Melanotan II and Setmelanotide?

Both are melanocortins. Melanotan II: A non-selective melanocortin agonist that causes tanning, appetite suppression and erections. Subject of repeated regulatory warnings. Setmelanotide: A selective MC4R agonist approved for rare genetic obesity syndromes, and a genuine precision medicine.

Which has stronger evidence, Melanotan II or Setmelanotide?

Setmelanotide has the stronger evidence base (regulator approved, about 10 human studies) compared with Melanotan II (preliminary human).

Are Melanotan II and Setmelanotide FDA approved?

Only Setmelanotide is FDA approved (Obesity due to POMC, PCSK1 or LEPR deficiency; Bardet-Biedl syndrome (Imcivree)). Melanotan II is not approved for any indication.

References

Regulatory and primary sources

  1. PubChem compound record (CID 92432) ↗ · structure, identifiers, synonyms
  2. FDA: Unapproved drugs and "research use only" products ↗ · regulatory status of non-approved products
  3. CAS Registry Number 121062-08-6 ↗ · chemical identity
  4. PubChem compound record (CID 11993702) ↗ · structure, identifiers, synonyms
  5. DailyMed: FDA-approved labeling for Setmelanotide ↗ · indications, dosing, warnings as approved
  6. FDA Drugs@FDA database ↗ · approval history
  7. CAS Registry Number 920014-72-8 ↗ · chemical identity

Published literature

  1. Janvier S, De Spiegeleer B, Vanhee C, et al.. Falsification of biotechnology drugs: current dangers and/or future disasters?.J Pharm Biomed Anal 2018.PubMed 30165334 · doi:10.1016/j.jpba.2018.08.037
  2. Hadley ME, Dorr RT. Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization.Peptides 2006.PubMed 16412534 · doi:10.1016/j.peptides.2005.01.029
  3. Bartness TJ, Vaughan CH, Song CK. Sympathetic and sensory innervation of brown adipose tissue.Int J Obes (Lond) 2010.PubMed 20935665 · doi:10.1038/ijo.2010.182
  4. Wessells H, Levine N, Hadley ME, et al.. Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II.Int J Impot Res 2000.PubMed 11035391 · doi:10.1038/sj.ijir.3900582
  5. Peters B, Hadimeri H, Wahlberg R, et al.. Melanotan II: a possible cause of renal infarction: review of the literature and case report.CEN Case Rep 2020.PubMed 31953620 · doi:10.1007/s13730-020-00447-z
  6. Allard J, Giuliano F. Central nervous system agents in the treatment of erectile dysfunction: how do they work?.Curr Urol Rep 2001.PubMed 12084236 · doi:10.1007/s11934-001-0044-6
  7. Dorr RT, Lines R, Levine N, et al.. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study.Life Sci 1996.PubMed 8637402 · doi:10.1016/0024-3205(96)00160-9
  8. Hadley ME. Discovery that a melanocortin regulates sexual functions in male and female humans.Peptides 2005.PubMed 15996790 · doi:10.1016/j.peptides.2005.01.023
  9. Faccioli N, Poitou C, Clément K, et al.. Current Treatments for Patients with Genetic Obesity.J Clin Res Pediatr Endocrinol 2023.PubMed 37191347 · doi:10.4274/jcrpe.galenos.2023.2023-3-2
  10. Markham A. Setmelanotide: First Approval.Drugs 2021.PubMed 33638809 · doi:10.1007/s40265-021-01470-9
  11. Mahmoud R, Kimonis V, Butler MG. Clinical Trials in Prader-Willi Syndrome: A Review.Int J Mol Sci 2023.PubMed 36768472 · doi:10.3390/ijms24032150
  12. Fox CK, Kelly AS, Reilly JL, et al.. Current and future state of pharmacological management of pediatric obesity.Int J Obes (Lond) 2025.PubMed 38321079 · doi:10.1038/s41366-024-01465-y
  13. Shoemaker A. Bardet-Biedl syndrome: A clinical overview focusing on diagnosis, outcomes and best-practice management.Diabetes Obes Metab 2024.PubMed 38383825 · doi:10.1111/dom.15494
  14. Anastasilakis AD, Paccou J, Palermo A, et al.. The effects of anti-obesity medications on bone metabolism: A critical appraisal.Diabetes Obes Metab 2025.PubMed 40555693 · doi:10.1111/dom.16541
  15. Miller JL, van Santen HM, Phillips SA, et al.. Setmelanotide for the Treatment of Acquired Hypothalamic Obesity.N Engl J Med 2026.PubMed 42418774 · doi:10.1056/NEJMoa2512275
  16. Clément K, van den Akker E, Argente J, et al.. Efficacy and safety of setmelanotide, an MC4R agonist, in individuals with severe obesity due to LEPR or POMC deficiency: single-arm, open-label, multicentre, phase 3 trials.Lancet Diabetes Endocrinol 2020.PubMed 33137293 · doi:10.1016/S2213-8587(20)30364-8

Literature retrieved from PubMed on October 18, 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.