OtherPeptideEvidence C4 cited

Melanotan II

Melanocyte Stimulating Hormone Analog

aka Melanotan 2 · MT-2 · MT-II · Ac-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-NH2

A synthetic hormone analogue researched for its ability to stimulate skin pigmentation via melanocortin receptors.

Molecular wt

1024.2g/mol

Formula

C50H69N15O9

CAS

121062-08-6

Half-life

1 h

clinical

Tmax

1 h

Route

Subcutaneous injection

PubChem

92432

Sequence

Read this before quoting the sequence

Cyclic lactam heptapeptide: a covalent amide bridge between the Asp side chain (residue 2) and the Lys side chain (residue 7) closes the ring. PubChem's systematic name records this as 'N-acetyl-L-norleucyl-L-alpha-aspartyl-L-histidyl-D-phenylalanyl-L-arginyl-L-tryptophyl-L-lysinamide, cyclic (2-7)-peptide'. Contains norleucine and D-phenylalanine, so a standard one-letter string is not applicable.

Source ↗

Mechanism of action

Melanotan II is a synthetic analogue of the alpha-melanocyte-stimulating hormone (α-MSH), which binds to melanocortin receptors, particularly MC1R, to stimulate melanin production in the skin. This results in increased pigmentation. It also affects MC4R, which is involved in appetite regulation and sexual function, leading to its effects on appetite suppression and libido enhancement.

What the evidence actually shows

Grade C

There are limited human trials on Melanotan II, primarily focusing on its effects on skin pigmentation and libido. These studies show increased pigmentation and libido, but the sample sizes are small and long-term safety data is lacking.

Regulatory status

Status

Not approved as a medicine in any jurisdiction. Sold only as unlicensed 'research' material.

Clinical stage

No active approved-track development identified. Human exposure in the published literature consists of small early-phase academic studies (Wessells 2000) plus a substantial case-report literature on self-administration harms.

research_compound

In the UK, Melanotan II is not licensed for medical use and is considered a research compound. It is not approved for human consumption.

Source ↗

Pharmacokinetics

Half-life

1 h

Tmax

1 h

Absorption

subcutaneous

Elimination

renal

Washout

3 days

Titration

Start 0.1mg daily ramp to 0.5mg

Low-confidence pharmacokinetics

These figures are recorded as clinical rather than measured in a published PK study. Treat them as an order of magnitude. Anything downstream of them — accumulation, steady state, washout — inherits that uncertainty.

Dosing — what backs each figure

Melanotan II has never been approved anywhere and no dosing regimen is established. Human exposure is limited to small supervised phase I and erectile-dysfunction studies using 0.01-0.03 mg/kg subcutaneously for at most two weeks, in which nausea, yawning/stretching and dose-limiting toxicity at 0.03 mg/kg were already evident; unsupervised use is associated with published harms including priapism, new and changing melanocytic lesions, mucosal pigmentation and rhabdomyolysis. A Phase 2 vitiligo trial (NCT07437560) is recruiting but does not disclose its dose.

ClinicalApproved labelling or a published human trial

0.01 mg/kg subcutaneously daily Monday-Friday for 2 consecutive weeks, escalated in 0.005 mg/kg increments to 0.025-0.03 mg/kg; the 0.03 mg/kg dose produced dose-limiting toxicity
3 healthy male volunteers, single-blind placebo-controlled pilot phase I study · subcutaneous
Dorr RT et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci 1996;58:1777-84 ↗
0.025 mg/kg subcutaneously, two single doses (crossover against vehicle), monitored over 6 hours
10 men with organic erectile dysfunction; a parallel study used the same route in 10 men with psychogenic erectile dysfunction · subcutaneous
Wessells H et al. Urology 2000;56:641-6 (organic ED); Wessells H et al. J Urol 1998;160:389-93 (psychogenic ED) ↗

Commonly circulatedNot established by any study

Dose: Research literature cites ~0.25 to 1 mg per dose
Frequency: Daily/EOD

Why this isn't evidence
Every published human exposure was weight-based (0.01-0.03 mg/kg, i.e. roughly 0.7-2.1 mg for a 70 kg adult) inside short supervised phase I/II protocols, and no source anywhere describes a 0.25-1 mg fixed dose, a daily/every-other-day maintenance schedule, or a loading-then-maintenance structure.

This figure is shown because it is what circulates and what people search for — not because it is supported. Cycle lengths in particular tend to be convention copied between compounds rather than anything derived from a compound's own pharmacokinetics.

No established human dose

No approved label or completed human trial establishes a dosing regimen for this compound. Anything presented as a standard protocol for it — anywhere — is someone's convention rather than a finding.

Handling and storage

No compound-specific stability data exists

No peer-reviewed or regulatory stability data specific to Melanotan II was located. There is no approved product and therefore no label storage section. Any temperature/duration figures circulating for this compound come from vendor material, which is not an acceptable source. Only generic lyophilised-peptide handling guidance exists. General peptide handling still applies — reconstitute gently, keep it cold, keep it dark — but any specific figure you see quoted for this compound elsewhere is someone's assumption, not a measurement.

→ Reconstitution walkthrough → Reconstitution calculator

Safety

Commonly reported

·Nausea
·Flushing
·"Increased libido"

Rarely reported

·Hyperpigmentation
·"Potential risk of melanoma"

Contraindications

·Pregnancy
·Breastfeeding
·"History of melanoma or skin cancer"

Drug interactions

·None well-documented, but caution advised with other melanocortin receptor agonists

Nausea, flushing, spontaneous erections, darkening of naevi, appetite loss

Reported combinations

Reported as synergistic

·Vitamin D for enhanced skin health

Reported as antagonistic

·None specifically documented

Combination claims in this dataset are largely unsourced and should be treated as folk knowledge until a citation appears beside them.

References (4)

Wessells H, Levine N, Hadley ME, Dorr R, Hruby V. (2000) Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II ↗
Int J Impot ResPMID 11035391DOI
Early controlled human studies reporting that subcutaneously administered Melanotan II produced penile erection and increased sexual desire in men with erectile dysfunction; nausea and yawning were prominent dose-limiting effects.
Hjuler KF, Lorentzen HF. (2014) Melanoma associated with the use of melanotan-II ↗
DermatologyPMID 24355990DOI
Case report of histologically confirmed melanoma in a 20-year-old fair-skinned woman who had self-injected melanotan-II for 3-4 weeks alongside sunbed use; the authors warn that the adverse-effect profile of this unlicensed drug is unknown.
Nelson ME, Bryant SM, Aks SE. (2012) Melanotan II injection resulting in systemic toxicity and rhabdomyolysis ↗
Clin Toxicol (Phila)PMID 23121206DOI
A man in his 30s who injected 6 mg of internet-purchased Melanotan II developed a sympathomimetic toxidrome with hypertension, tachycardia, mydriasis, tremor, renal dysfunction and rhabdomyolysis (CPK peak 17,773 IU/L), requiring three days of intensive care.
Devlin J, Pomerleau A, Foote J. (2013) Melanotan II overdose associated with priapism ↗
Clin Toxicol (Phila)PMID 23537392DOI
Case report of priapism following Melanotan II overdose. Further independent priapism case reports exist (PMID 30796078, BMJ Case Rep 2019; PMID 33460908, Sex Med 2021).

Data provenance

Chemistry and citations on this page were checked against primary sources on 2026-08-14. Values that could not be verified were left blank rather than filled with a plausible guess.

Could not verify
storage.lyophilized, storage.reconstituted, storage.lightSensitive, reconstitution.solvent, regulatory.wada

Research use only

This profile is educational reference material. It is not medical advice, not a prescription, and not an endorsement of self-administration. Compounds discussed here are research chemicals and most are not approved for human therapeutic use.

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