What the human research shows
A rare grey-market peptide with genuine (if small) human efficacy data — and exactly the reason approval matters: the same melanocortin activity that tans skin also drives nausea, priapism and changes to moles that complicate melanoma detection. Real signal, unquantified risk, no oversight.
Evidence profile0–5
- Metabolic & weight—0.0
- Cardiovascular—0.0
- Muscle & growth—0.0
- Healing & repair—0.0
- Neuro & sleep—0.0
- Immune & inflammation—0.0
- Sexual & hormonalC1.3
- Skin & appearanceC1.3
- Ageing & longevity—0.0
| Outcome | Grade | Effect size | Human studies | Where the evidence comes from |
|---|---|---|---|---|
| Erectile function (psychogenic ED) | CWeak | Moderate | Small crossover RCTs | In a 10-man double-blind crossover, Melanotan II produced clinically apparent erections in most treated men, far exceeding placebo — small, early, never taken to phase 3.1 |
| Skin tanning | CWeak | Moderate | Pilot studies (n≈3–12) | A pilot phase 1 study showed measurable tanning from a few low subcutaneous doses. The related peptide melanotan-1 (afamelanotide) went on to be developed properly and approved for a rare photosensitivity disorder; melanotan II did not.2 |
| Safety in humansadverse | CWeak | Moderate | Trials + case reports | Nausea, flushing, spontaneous erections and darkening of moles are common; case reports describe rhabdomyolysis and kidney infarction, and dermatologists warn that new or changing moles can mask melanoma. No systematic long-term safety data exist.13 |
Literature searched to 3 September 2026. Human studies only; animal and cell work informs the mechanism section and nothing else.
Registered trials
ClinicalTrials.gov lists 1 interventional study naming Melanotan II as an intervention, 1 recruiting, and none with results posted to the registry.
A registration is not a result. Anyone can register a study, and many never report — so this list shows what has been attempted, not what has been shown. The graded evidence above is the answer to whether something works.
| Study | Phase | Status | Participants | Sponsor | Results |
|---|---|---|---|---|---|
| Melanotan II (MT-II) as an Adjunct to NB-UVB Phototherapy for Repigmentation in Stable Nonsegmental VitiligoNCT07437560 · started Feb 2026 | Phase 2 | Recruiting | 60* | Hudson Biotech | None |
Participant counts marked * are the sponsor's estimate, not a final enrolment. Source: ClinicalTrials.gov, read directly from the registry and refreshed weekly.
What it is
Melanotan II is a cyclic seven-residue analogue of α-MSH, the hormone that stimulates pigment cells. It was designed as a tanning agent — the idea being a tan without the ultraviolet — and the erection effect was discovered along the way.
It is sold as an injectable 'tanning peptide', often alongside claims about libido. It is not, and has never been, an approved medicine.
How it is thought to work
It activates melanocortin receptors broadly: MC1R in skin (pigment) and MC4R in the brain (sexual arousal and appetite suppression). Because it is non-selective, the wanted and unwanted effects — tanning, erections, nausea, mole changes — come as a package.
What is still unknown
- The real rate of serious adverse events, since use is unmonitored and case reports capture only the extremes.
- Whether accelerating pigmentation of moles raises melanoma risk or merely hides it.
- Any long-term safety data at the doses people actually use.
The molecule and how long it lasts
- Formula
- C50H69N15O9
- Molecular weight
- 1024.2 g/mol
- CAS number
- 121062-08-6
- PubChem
- CID 92432
PubChem record, read 23 September 2026.
- Route
- Subcutaneous in the 1996 pilot study, which reports no PK
- Half-life
- No human pharmacokinetic data
No pharmacokinetic study in people: Dorr RT, et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide, in a pilot phase-I clinical study. Life Sci 1996
Regulatory status
No marketing authorisation. National regulators (including in the UK and Nordic countries) have repeatedly warned against injectable melanotan sold online.
Not approved by the FDA, which has warned consumers about melanotan products sold for tanning. The properly developed sibling, afamelanotide (Scenesse), is approved for a rare photosensitivity disorder — melanotan II is not.
Not licensed by the MHRA. Selling or supplying it for human use is an offence under the Human Medicines Regulations 2012.
Not on the ARTG. Supply without a prescription is unlawful; imports are seized.
No Drug Identification Number; selling it for human use is illegal.
Not specifically named on the 2026 WADA Prohibited List, though as a non-approved substance it may fall under S0; athletes should verify.
Questions people actually ask
Does Melanotan II actually work for tanning?
Is it the same as the approved 'Scenesse'?
Why do regulators warn about it?
One page per claimed effect
- CDoes Melanotan II help with erectile function?Small crossover RCTs
- CDoes Melanotan II help with skin tanning?Pilot studies (n≈3–12)
- CHow common is safety in humans with Melanotan II?Trials + case reports
References
- 1Wessells H, et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: a double-blind, placebo-controlled crossover study.J Urol, 1998;160:389–39310 men, crossover; the erection data.
- 2Dorr RT, et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide, in a pilot phase-1 clinical study.Life Sci, 1996;58:1777–17843 volunteers; the tanning data.
- 3Case reports of serious harm with melanotan II (e.g. renal infarction).CEN Case Rep and others, 2020Illustrative of the unmonitored-use risk.
Change log
- 2026-09-03Initial publication. Grade C — real small-trial efficacy, unquantified real-world harm.