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How Melanotan II Works: Mechanism and Pharmacology

How Melanotan II works: its target and mechanism as the sources state them, how long it acts, and what is still unknown.

Medical review pendingMelanocortin agonistUpdated
Class
Melanocortin agonist
FDA status
Not approved
Off Category 2, 15 Apr 2026
Routes studied
subcutaneous; self-injection; intranasal
Half-life
[pending]
by route, with source

How long it acts

No published half-life found for Melanotan II (PubMed search, 2 Oct 2026)

Full detail, including drug-testing windows, is on the Melanotan II half-life page.

What melanotan II acts on

The first pilot describes melanotan II as a cyclic heptapeptide analog of alpha-MSH with superpotent melanotropic activity in vitro.[5]

A forum study describes it as an alpha-MSH analogue that induces skin hyperpigmentation through the melanocortin 1 receptor.[6]

The erectile-dysfunction review calls it a non-selective melanocortin receptor agonist, so its effects are not confined to the skin.[7]

A rat stress study repeats that melanotan II is a potent agonist of melanocortin receptors, as an analog of the ACTH(4-10) fragment.[8]

What is seen in the body

In the 3-volunteer pilot, the 0.03 mg/kg dose produced Grade II somnolence and fatigue in one of two subjects, and mild nausea appeared at most dose levels.[5]

In rats, central melanotan II inhibits feeding and suppresses the appetite-driving action of neuropeptide Y; this is animal data on appetite pathways.[9]

A renal-infarction review notes earlier reports of rhabdomyolysis and renal failure with melanotan II and considers thrombotic and direct toxic effects.[10]

Does it work without sun?

The only human pilot reported tanning activity after 5 low subcutaneous doses every other day; its abstract does not describe sun exposure either way.[5]

A melanoma case report describes melanotan-II in combination with the use of sun tanning beds, so sun exposure was part of that user's routine.[11]

What is not known

Drugs@FDA returns no match for melanotan, so there is no label section on mechanism of action to quote.[12]

A PubMed search for melanotan II with half-life or pharmacokinetic terms, run on 2 Oct 2026, returned 3 records; the human mechanism rests on the pilot and the case reports quoted here.

Calculated from query ("melanotan II"[tiab] OR "melanotan 2"[tiab]) AND (half-life[tiab] OR pharmacokinetic*[tiab]); date 2026-10-02; count 3. Formula: count as recorded in evidence/melanotan-2.json searches

Common questions

How long does Melanotan II act in the body?

We found no published half-life for Melanotan II (PubMed search, 2 Oct 2026), so how long it acts is unknown.

How does melanotan 2 work?

Melanotan II is described as a non-selective melanocortin receptor agonist, meaning it binds several melanocortin receptors rather than one.[7]

Does melanotan 2 work without sun?

Human data cannot answer it: 1 pilot of 3 men reported pigmentation, and its abstract is silent on sun, so the number of studies that tested tanning with and without sun is 0.

Calculated from pilots reporting pigmentation 1; studies comparing sun and no sun 0. Formula: count = 0

More on Melanotan II

DosageDoses used in published studies, with the source for each.CalculatorVial, water and dose to syringe units.Side effectsWhat labels and studies report, and what is unknown.ResultsStudy outcomes and when they were measured.PricePrice per mg and per week from dated listings. No vendor links.BenefitsClaimed benefits next to what published studies measured.

Sources

  1. 1PubMed search: "melanotan II"[tiab] OR "melanotan 2"[tiab] (198 results)PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026
  2. 2PubMed search: ("melanotan II"[tiab] OR melanotan[tiab]) AND humans[mh] (82 results)PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026
  3. 3PubMed search: ("melanotan II"[tiab] OR "melanotan 2"[tiab] OR melanotan[ti]) AND (case[tiab] OR naevi[tiab] OR nevi[tiab] OR melanoma[tiab] OR adverse[tiab] OR priapism[tiab] OR tanning[tiab] OR sunless[tiab]) AND humans[mh] (25 results)PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026
  4. 4PubMed search: ("melanotan II"[tiab] OR "melanotan 2"[tiab]) AND (half-life[tiab] OR pharmacokinetic*[tiab]) (3 results)PubMed · 2026pubmed.ncbi.nlm.nih.govAccessed 2 Oct 2026
  5. 5Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study.Life sciences · 1996PMID 8637402Accessed 2 Oct 2026
  6. 6Melanotan II User Experience: A Qualitative Study of Online Discussion Forums.Dermatology (Basel, Switzerland) · 2021PMID 34464955Accessed 2 Oct 2026
  7. 7Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II.International journal of impotence research · 2000PMID 11035391Accessed 2 Oct 2026
  8. 8Antidepressant-like and antistress effects of the ACTH(4-10) synthetic analogs Semax and Melanotan II on male rats in a model of chronic unpredictable stress.European journal of pharmacology · 2024PMID 39442746Accessed 2 Oct 2026
  9. 9The melanocortin agonist Melanotan-II reduces the orexigenic and adipogenic effects of neuropeptide Y (NPY) but does not affect the NPY-driven suppressive effects on the gonadotropic and somatotropic axes in the male rat.Journal of neuroendocrinology · 2003PMID 12535159Accessed 2 Oct 2026
  10. 10Melanotan II: a possible cause of renal infarction: review of the literature and case report.CEN case reports · 2020PMID 31953620Accessed 2 Oct 2026
  11. 11Melanoma associated with the use of melanotan-II.Dermatology (Basel, Switzerland) · 2014PMID 24355990Accessed 2 Oct 2026
  12. 12Drugs@FDA (openFDA) search: active ingredient "melanotan"U.S. Food and Drug Administration · 2026api.fda.govAccessed 2 Oct 2026

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