About Melanotan II
Melanotan II is a synthetic analog of alpha-melanocyte stimulating hormone that activates multiple melanocortin receptors. Studied for skin pigmentation and sexual arousal; widely used recreationally for tanning.
Skin & Hair
Melanotan II
Synthetic alpha-MSH Analog
A synthetic melanocortin agonist studied for tanning and sexual arousal.
PreclinicalResearch use only
Where to buy
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Evidence level
Preclinical only
A synthetic cyclic heptapeptide and non-selective melanocortin receptor agonist (MC1R/MC3R/MC4R/MC5R). Originally developed for photoprotective tanning; widely used recreationally for skin pigmentation and as a libido enhancer.
Mechanism
Agonist at MC1R (pigmentation), MC3R and MC4R (libido and appetite).
Researched benefits
Skin pigmentation
MC1R agonism increases eumelanin synthesis in melanocytes. Subcutaneous dosing produces visible tanning in most skin types, often with little to no UV exposure required. Effect is reproducible across small open-label cohorts.
Sexual arousal and erectile response
MC3R and MC4R activation in the hypothalamus produces pro-erectile and pro-libido effects in both men and women. PT-141 (bremelanotide), a metabolite-derived analog, was approved on this mechanism for HSDD in 2019.
Appetite suppression
MC4R activation suppresses food intake. Most users experience nausea and reduced appetite for the first several doses, which sometimes drives incidental weight loss.
Risks & cautions
- high
Melanoma and atypical nevus risk
Case reports describe rapid darkening of existing moles, eruption of new nevi, and several published cases of melanoma diagnosed after Melanotan II use. Causality versus correlation is unsettled, but anyone with personal or family history of skin cancer should avoid this peptide.
- moderate
Nausea and flushing
Acute nausea is near-universal at the first several doses, often with facial flushing and yawning within 30 minutes of injection. Tolerance develops, but the initial doses are unpleasant.
- moderate
Priapism
Prolonged erections lasting hours have been reported. Rare but documented.
- moderate
Unregulated peptide quality
Most Melanotan II in circulation is research-grade with variable purity. Bacterial contamination from poor reconstitution practice has caused injection-site abscesses.
- high
Long-term safety unknown
No long-term human safety data exists. Most users self-administer for cosmetic reasons without medical oversight.
Dosing
Start at 250 mcg subcutaneously and titrate up by 250 mcg every few days as tolerated, to a typical loading range of 500–1000 mcg per dose 3–5 times weekly until desired pigmentation; then taper to a maintenance dose every 5–10 days.
- Conservative
- 250 mcg × 2–3/week
- Standard
- 500–1000 mcg × 3/week during loading
- Aggressive
- 1 mg daily during loading (not recommended)
Vial sizes
10mg
Half-life
~30 minutes
Route
subcutaneous
Reconstitute with bacteriostatic water. Inject into subcutaneous abdominal fat. Nausea is worse on an empty stomach — many users dose before bed. Effective tanning typically requires concurrent moderate UV exposure to maximize melanogenesis.
Contraindications
- Personal or family history of melanoma or atypical nevi
- Active cardiovascular disease (melanocortin agonism raises blood pressure transiently)
- Pregnancy or breastfeeding — no data
- Pre-existing erectile dysfunction medication use without supervision
In depth
Background
Melanotan II was developed at the University of Arizona in the 1980s under Mac E. Hadley as a photoprotective drug — the idea being that if you could induce a tan pharmacologically you could reduce UV-driven skin cancer risk. The drug was never brought to market for that indication. A related molecule, bremelanotide (PT-141), was eventually approved for hypoactive sexual desire disorder in premenopausal women.
The recreational market is large. Melanotan II is sold online globally, used heavily in the UK, Scandinavia, and Australia, and has been the subject of multiple public health warnings.
Mechanism in depth
Melanotan II is a non-selective melanocortin agonist:
- MC1R (melanocytes): drives eumelanin synthesis — darker, more photoprotective pigment.
- MC3R (hypothalamus, others): involved in energy balance and inflammation.
- MC4R (hypothalamus): mediates appetite suppression and pro-erectile effects.
- MC5R (exocrine glands): the pathway behind the sebum and tanning-bed-smell reported by users.
The non-selectivity is why side effects (nausea, libido changes, appetite loss) cluster together — they're all melanocortin pathway effects, not idiosyncratic.
Human evidence
Limited formal evidence; substantial gray literature:
- Dorr 1996 ran a small phase-I dose-escalation study and established the basic safety/tolerability profile and confirmed tanning.
- Multiple case series and dermatology case reports document mole darkening and melanoma diagnoses post-use.
- PT-141 was approved on phase-III bremelanotide trials, indirectly confirming the MC4R-driven sexual response.
There are no long-term safety studies of recreational Melanotan II in any cohort.
Animal evidence
Originally validated in frog skin assays (a classic melanocortin readout) and rodent erection / mating studies. The pharmacology is well-characterized at the receptor level.
Stack synergy
Often combined with:
- Moderate UV exposure — required for maximum tanning response.
- Anti-emetics (ondansetron) — used by some to mitigate first-dose nausea.
Avoid stacking with PDE5 inhibitors without supervision — additive vasodilation and priapism risk.
Open questions
- Does Melanotan II actually cause melanoma, or does it accelerate detection of existing dysplastic nevi by making them visible?
- What is the cumulative lifetime dose ceiling above which mole changes become persistent?
- Is the cardiovascular effect of melanocortin agonism clinically significant in healthy users?
- Why does tolerance to nausea develop but the pro-erectile effect persists?
References
- 1.Dorr R.T. et al. — Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study (Life Sci, 1996)
- 2.Cardinal J. et al. — Cutaneous melanoma associated with melanotan use (Australas J Dermatol, 2010)
- 3.Hjuler K.F., Lorentzen H.F. — Melanoma associated with the use of melanotan-II (Dermatology, 2014)
- 4.Brennan R. et al. — A review of the recreational use of the melanocortin receptor agonist melanotan-II (Drug Test Anal, 2017)