Melanotan II (MT-II)
Synthetic cyclic α-MSH analog, first-generation
At a glance
What it is: Synthetic cyclic α-MSH analog, first-generation.
Primary research applications:
- Grey-market use for tanning
- Claimed: appetite suppression and libido
Editorial summary: Melanotan II was developed as a possible tanning / skin-protection agent but never approved anywhere. Its broad melanocortin receptor activity produces tanning along with nausea, pigmentation changes including new moles, and potential cardiovascular effects. Grey-market use is widespread despite the lack of approval.
What is Melanotan II?
Melanotan II is a synthetic cyclic analog of alpha-MSH, developed at the University of Arizona in the 1980s as a potential agent for inducing protective pigmentation to reduce UV-induced skin damage. Development as a regulated pharmaceutical was discontinued; no regulatory body has approved MT-II for any indication.[1]
Mechanism of action
Activates all melanocortin receptors (MC1R through MC5R), producing:
- MC1R activation → melanin synthesis, tanning
- MC3R/MC4R activation → appetite suppression, sexual effects, sympathetic activation
- MC5R activation → exocrine gland effects
The non-selective receptor activity is what distinguishes MT-II from PT-141, which is more selective for MC3/MC4 and was developed specifically for sexual indications.
What the research shows
The peer-reviewed literature on Melanotan II is summarized below across two tiers: human research (the highest standard), and preclinical / emerging research (animal models and early-stage human work).
Claims and the evidence behind them
This table summarizes commonly discussed claims and how the published evidence weighs in. The aim is clarity — supported claims, claims that look promising but need more data, and claims that outrun the science.
| Claim | What the evidence shows | Verdict |
|---|---|---|
| Produces skin tanning without UV | Supported by small academic studies and extensive user reports | Supported |
| Protects against UV-induced skin damage | Hypothesized; not established in outcome trials | Preliminary |
| Causes new moles and darkening of existing moles | Well-documented | Supported |
| Suppresses appetite | Consistent with MC4R mechanism; often reported | Plausible |
| Is safe for long-term use | Not established; concerning case reports | Unsupported |
Reported user experiences
How the research describes administration
Grey-market subcutaneous injection. There is no approved clinical protocol.
Editorial note
Administration details above describe how the peptide is given in published studies. We summarize this for educational completeness — these descriptions are not protocols, dosing recommendations, or instructions for personal use. Decisions about treatment require an appropriately licensed clinician.
Safety considerations and open questions
The takeaway
Melanotan II produces the advertised tanning effect, but at the cost of a non-trivial adverse event profile and no regulatory oversight. Dermatologists have raised serious concerns about pigmented skin lesion changes in users. The newer, more selective PT-141 inherits the 'desire and libido' piece of MT-II's effects with a cleaner profile for sexual indications.
Frequently asked questions
Is Melanotan II approved?
No. It has no regulatory approval anywhere in the world. It is sold as a research chemical.
Does Melanotan II cause melanoma?
No direct causal link has been established, but dermatologists have documented concerning pigmented lesion changes and atypical nevi in users. Any new or changing moles should be evaluated.
How is Melanotan II different from PT-141?
PT-141 (bremelanotide) is a more selective analog approved for female sexual dysfunction with a cleaner side-effect profile. Melanotan II is older, less selective, and not approved anywhere.
Does Melanotan II suppress appetite?
Commonly reported. The MC4R activation that contributes to this effect is also the target of anti-obesity melanocortin drugs in development.
References
- Dorr RT, Ertl G, Levine N, Brooks C, Bangert JL, Powell MB, Humphrey S, Alberts DS. Effects of a superpotent melanotropic peptide in combination with solar UV radiation on tanning of the skin in human volunteers. Arch Dermatol. 2004;140(7):827-35. https://pubmed.ncbi.nlm.nih.gov/15262693/
- Cardones AR, Grichnik JM. alpha-Melanocyte-stimulating hormone-induced eruptive nevi. Arch Dermatol. 2009;145(4):441-4. https://pubmed.ncbi.nlm.nih.gov/19380666/