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Melanotan II

C

lead outcome

Skin tanning (the marketed use)

grades vary by outcome ↓

Peptide

also called — Melanotan II · MT-II · MT-2 · "the tanning peptide" · a synthetic α-MSH analog. INCI: none · Melanotam 2

skin tanningsexual arousal (gray-market / research)

Reference entry — not sold here. Melanotan II is not approved anywhere, sits in FDA Category 2 (significant safety risks), and is illegal to sell for human use in most countries. Unusually for this register, the marketed effect (tanning) is real — but the compound is genuinely unsafe, which is the whole point of the page. No dosing published here.

In brief

Melanotan II is a non-selective melanocortin agonist — the original "tanning peptide." It genuinely does induce a tan (and arousal), but it is not approved anywhere, sits in FDA Category 2 for safety risks, and is linked in case reports to serious harms — priapism, mole/pigment changes, rhabdomyolysis, kidney injury and more. "Safe sunless tanning" is a dangerous misframing. Its erectile side effect gave rise to the FDA-approved drug PT-141 (#46), and its relative Melanotan I (afamelanotide) is separately approved for a rare disease — but MT-II itself is the unapproved, higher-risk one.

Legal standing, by region

European Union

illegal to sell for human use

illegal to sell for human use; nonetheless widely available through internet vendors and gym/salon networks, marketed as a tan.

United States

Not FDA-approved (503A Cat. 2)

FDA classifies MT-II in Category 2 of the 503A bulks list (a substance that raises significant safety risks for compounding).

Evidence, by outcome

How we grade →

An honest grade per outcome — drawn from the evidence, not any catalogue. Hype and undemonstrated marketing claims grade low.

OutcomeEvidence base · effectGrade

Skin tanning (the marketed use)

The effect is real, but no completed safety/efficacy trial; not approved; efficacy is not the problem — safety is

Small human studies (Dorr 1996; Phase 1 tanning) · Genuine, dose-dependent tanning

C

Erectile / arousal effect

This effect became PT-141's domain; MT-II itself unapproved

Small trials (Wessells 1998) · Erection induction

C

"Safe sunless tanning" claim

The risk profile below makes "safe" inaccurate

— · Misframing

F

Safety / serious adverse events

Documented in case reports: priapism (sometimes needing surgery), changing/darkening moles (complicating melanoma detection), rhabdomyolysis, renal infarction, posterior reversible encephalopathy syndrome (PRES); plus routine nausea/flushing. Whether MT-II causes melanoma is unproven and confounded by users' extra UV-seeking — but the pigment/mole changes are a real monitoring problem

Case-report literature + trial AEs · Serious concerns

—

Disclosure

Vallydia sells its own cosmetic serums, and some ingredients graded here belong to the same categories as those products. Grades are drawn from the published evidence by the method we publish, and applied to our own ingredients on the same terms — our copper-peptide serum is graded no more kindly than the peptides it competes with. We disclose the interest so you can weigh it.

Trade names shown here (for example Matrixyl, Argireline, Syn-Ake) are the property of their respective owners and are used only to identify the ingredient under discussion. Their appearance implies no affiliation with, or endorsement by, the proprietor.

Evidence changes

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Identity

a synthetic cyclic heptapeptide (7 amino acids), sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂ — a non-selective melanocortin agonist (activates MC1R, MC3R, MC4R and MC5R), up to ~1000× more potent than natural α-MSH at stimulating melanin, and able to cross the blood-brain barrier (hence the central effects).

Development & history

Groundwork: 1960s research showed α-MSH triggered sexual arousal in rats; interest carried into the 1980s.
At the University of Arizona (1980s–early 1990s), Mac E. Hadley and Victor J. Hruby set out to build α-MSH analogs as sunless-tanning / skin-cancer-chemoprevention agents — the idea being a protective tan without UV. They synthesised Melanotan-I and Melanotan II.
The pivotal accident: while self-experimenting with Melanotan II, one of the scientists injected ~twice the intended dose and got an ~eight-hour erection, plus nausea and vomiting — revealing that MT-II acts centrally (MC4R) as well as on skin (MC1R). A 1996 pilot (Dorr et al., Life Sciences, 3 volunteers) then documented dose-dependent tanning alongside nausea, flushing and spontaneous erections.
Australian-government-funded human trials followed (Hadley, late 1990s), but the side-effect burden showed it was impractical as a drug, and it was never approved. The erection finding was spun off into PT-141 / bremelanotide (#46) — which was eventually FDA-approved. MT-II itself went gray-market, sold online and in tanning salons and gyms from the mid-2000s.

Mechanism (as proposed)

a non-selective melanocortin agonist — MC1R on skin melanocytes → melanin synthesis (tanning); MC4R in the hypothalamus → sexual arousal/erection and appetite suppression; plus MC3R/MC5R. Because it crosses the blood-brain barrier, the central (MC4R) effects accompany the skin (MC1R) effect — which is exactly why a "tanning" compound also causes erections, nausea and other systemic effects.

Chemical identifiers

Cross-reference identifiers for the authoritative external databases — not a recipe, and nothing about how to use it.

PubChem CID92432

InChIKeyJDKLPDJLXHXHNV-MFVUMRCOSA-N

SMILESCCCC[C@@H](C(=O)N[C@H]1CC(=O)NCCCC[C@H](NC(=O)[C@@H](NC(=O)[C@@H](NC(=O)[C@H](NC(=O)[C@@H](NC1=O)CC2=CN=CN2)CC3=CC=CC=C3)CCCN=C(N)N)CC4=CNC5=CC=CC=C54)C(=O)N)NC(=O)C

UNIIUPF5CJ93X7

ChEMBLCHEMBL430239

via PubChem exact-name match (Melanotan II) · high confidence

Sources — 4 cited

01Dorr RT, et al. (Phase 1 pilot of melanotan-II — tanning + adverse effects.) Life Sci. 1996.

02Wessells H, et al. (Melanotan-II erectile-response trials.) J Urol, 1998.

03Hadley ME. Discovery that a melanocortin regulates sexual functions in male and female humans. Peptides. 2005.

04Case-report literature on priapism, melanoma/nevus changes, rhabdomyolysis, renal infarction, PRES; melanoma-risk reviews (2013; 2021).

Updated 2026-07-13

Grades reflect the published evidence, not our interest. No dosing, reconstitution, or administration is published for research compounds — that restraint is deliberate.

Related compounds

PT-141 (Bremelanotide)B

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This site provides neutral scientific reference and sells only products lawful in your region. Nothing here is medical advice, a recommendation, or an offer to supply unapproved medicines. No dosing or administration is published for research compounds. Cosmetic peptides per Regulation (EC) 1223/2009. Unapproved injectable peptides are neither sold nor advertised in the EU (Directive 2001/83/EC, Title VIII). © 2026 Vallydia.