Overview

Sold as the "Barbie drug" for tanning without sun exposure. It is the clearest example on this site of a peptide where the documented harms are concrete and the regulatory position is unanimous.

Not approved for human use anywhereNo approval anywhere for human use. Sold under research-use labelling. Illegal to sell for human use in the US, UK, EU and Australia. Not approved anywhere.

At a glance

Regulatory status	Not approved anywhere. Regulators in the US, UK, Australia and across the EU have issued explicit consumer safety warnings against it.
Drug class	Non-selective melanocortin receptor agonist (MC1R/MC3R/MC4R/MC5R)
Route	Subcutaneous (illicit)
Half-life	~1–2 hours
Evidence rating	1/5 Minimal Evidence rating 1 out of 5: Minimal Animal or laboratory data only. No human efficacy evidence.
Studied in	Early academic studies of tanning and sexual function in the 1990s. No completed development program; superseded by the selective and approved afamelanotide.

How it works

Non-selective melanocortin agonism. MC1R activation drives melanogenesis (the tanning effect), MC4R activation produces the appetite suppression and sexual arousal effects, and MC5R and other receptor activity accounts for much of the unpredictable side-effect profile.

Evidence base

Rated 1 of 5 — Minimal. Animal or laboratory data only. No human efficacy evidence.

A rare case where the harm literature is more developed than the benefit literature.

Benefits & potential uses

Bars indicate how well each claim is supported: three = strong human evidence, two = moderate, one = preliminary or preclinical.

Produces tanning without UV Preliminary

The MC1R effect is real and reliable — melanogenesis without sun exposure.
Appetite suppression Preliminary

MC4R-mediated; reported consistently by users.
Sexual arousal effects Preliminary

The observation that led to the development of PT-141, which is the approved and far better-characterised alternative.

Risks, cons & cautions

Bars indicate seriousness: three = serious or common, two = moderate, one = minor.

Melanoma and changing moles Serious

Multiple case reports describe new or rapidly changing melanocytic lesions and melanoma diagnoses in users. It stimulates the exact cells involved.
Rhabdomyolysis Serious

Case reports of severe rhabdomyolysis with acute kidney injury following use.
Priapism Serious

Prolonged painful erection requiring emergency intervention has been reported; untreated priapism causes permanent damage.
Severe nausea and vomiting Moderate evidence

Very common and often severe, particularly with the first doses.
Uncontrolled and unpredictable dosing Serious

Sold as unregulated powder requiring self-reconstitution, with no standardised dose.
Regulator warnings worldwide Serious

FDA, MHRA, TGA and EU authorities have all warned consumers specifically against this product.
Injection-related infection Serious

Non-sterile reconstitution and repeated self-injection have caused abscesses and systemic infection.

Who should avoid it

Everyone — regulators globally advise against use. Anyone with atypical naevi, melanoma history or fair skin faces particularly elevated risk

If used under medical supervision, monitor

If used despite advice: dermatologic surveillance with full-body skin examination

Commonly confused with

These mix-ups cause real harm — two products sold under one name, or two molecules whose effects run in opposite directions.

Afamelanotide FDA Approved Evidence 5/5

The critical distinction on this site. Afamelanotide (Melanotan I) is a selective MC1R agonist, FDA-approved, delivered as a physician-implanted device for a rare photosensitivity disease. Melanotan II is non-selective, unapproved, self-injected, and the subject of worldwide regulator warnings including melanoma case reports.

Compare side by side

PT-141 (Bremelanotide) FDA Approved Evidence 5/5

PT-141 was developed from Melanotan II specifically to isolate the sexual-arousal effect without the pigmentation effect. PT-141 is FDA-approved for one indication; Melanotan II is approved nowhere.

Compare side by side

Regulatory & legal status

Illegal to sell for human use in the US, UK, EU and Australia. Not approved anywhere.

Infographic

Melanotan II — benefits & risks at a glance Download SVG

Where to read further

We link to live literature searches rather than a frozen citation list, so you always see current results — including anything published after our last review.

tanningmelanocortinhigh riskregulator warningsillegal

Related peptides in Sexual Health & Melanocortin

Terms used on this page

Satiety vs Satiation: Satiation is the set of signals that ends a meal in progress, while satiety is the post-meal inhibition that determines how long it takes before eating begins again.
Sexual Desire vs Arousal: Sexual desire is the motivational interest in sexual activity while arousal is the genital and subjective response to stimulation, and the two dissociate enough that trials measure them separately.
Melanogenesis: Melanogenesis is the enzymatic synthesis of melanin inside melanosomes and the subsequent transfer of those pigment granules to surrounding keratinocytes, where they shield nuclear DNA.
Melanocortin System: The melanocortin system is the POMC-derived signalling network in which alpha-MSH and ACTH act on five receptors to control pigmentation, adrenal steroid output, appetite and energy balance.
Agonist: An agonist is a ligand that binds a receptor and stabilises its active conformation, producing a biological response rather than merely occupying the binding site.
Melanocortin-1 Receptor (MC1R): MC1R is the G protein-coupled receptor on melanocytes that, when bound by alpha-MSH or ACTH, raises cyclic AMP and switches pigment synthesis from pheomelanin toward eumelanin.

This page is educational information, not medical advice. It cannot account for your medical history, medications, or risk factors. Do not start, stop or change any treatment based on it. Speak to a qualified healthcare professional who knows your case.