Melanotan II

MT-II is a cyclic, protease-resistant analogue of alpha-MSH with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2. MC1R activation on melanocytes raises cyclic AMP and shifts pigment synthesis from phaeomelanin toward eumelanin, which is the darker, more photoprotective pigment - so the tan is real melanin, not a dye. Central MC4R and MC3R activation produces the libido effect and the appetite suppression, and MC1R activity in vasculature and mast cells produces the flushing and nausea. Because it hits every melanocortin receptor, you cannot get the tanning without the systemic effects, which is precisely the problem PT-141 and afamelanotide were each designed to solve from opposite directions.

Targets: MC1R, MC3R, MC4R, MC5R, Melanocyte adenylate cyclase

• · Run for 1 to 3 weeks until you reach the pigment level you want. Fair, redheaded, MC1R-variant skin responds slowest and needs the longest load.
• · Once the target shade is reached, one or two doses a week plus occasional UV holds it. Survey data show adverse events roughly double above 1 mg per administration, so there is no good reason to exceed that.

Work out your exact syringe units →

• very commonNausea— Worst in the first few doses, largely tolerises within a week.
• very commonFacial flushing— Almost universal on early doses.
• very commonAppetite suppression— Often welcomed, but it is a real MC4R effect and can be marked.
• very commonDarkening of moles, freckles and nipples— Survey data put mole darkening around 70 percent of users. It genuinely obscures the visual signs used to detect melanoma early.
• commonSpontaneous erections— In men, often unwanted and poorly timed for the first week of loading.
• commonNew melanocytic naevi— Eruptive naevi after MT-II injection are documented in dermatology case series.
• commonYawning and stretching complex— A classic melanocortin effect, harmless.
• rareMelanoma— Multiple published case reports link melanoma - including a 2025 oral mucosal case with nasal-spray use - to MT-II. Causation is unproven but the biological rationale is not far-fetched.
• rareRhabdomyolysis and renal injury— Isolated case reports, usually with high doses or contaminated product.

• Personal or family history of melanoma or dysplastic naevus syndrome - this compound both stimulates melanocytes and hides the warning signs.
• Large numbers of atypical moles, where surveillance depends on colour change.
• Pregnancy and breastfeeding - no data, and melanocortin signalling is developmentally active.
• Uncontrolled hypertension or significant cardiovascular disease.

• redundantpt-141 — PT-141 is MT-II's own metabolite. Running both is the same drug twice.
• redundantmelanotan-1 — Both drive MC1R pigmentation; MT-I does it without the sexual and nausea effects.
• synergyUV exposure — MT-II needs some UV stimulus to produce a visible tan. Users routinely underestimate how little is needed and burn anyway - the peptide is not sunscreen.
• cautionPhotosensitising drugs such as tetracyclines or isotretinoin — The tan gives a false sense of protection while these still sensitise the skin.

• · Get a full-body mole map or a set of dated photographs before you start, and repeat annually.
• · See a dermatologist promptly for any mole that changes shape, bleeds or becomes asymmetric - do not write it off as 'the peptide darkening things'.
• · Track blood pressure if you have any cardiovascular risk.

Not approved anywhere for human use. Sale for human consumption is explicitly prohibited in the UK, Australia, Norway, Denmark and elsewhere, and multiple national health agencies have issued warnings. Sold online as a research chemical.

• Dorr et al. 1996, evaluation of melanotan-II in humans, Life Sciences (trial)
• Wessells et al. 2000, Melanotan II for erectile dysfunction, International Journal of Impotence Research (trial)
• Cousen et al. 2009, eruptive melanocytic naevi following melanotan injection, British Journal of Dermatology (other)
• DermNet NZ, Melanotan II clinical overview (review)

Every melanocortin receptor is Gs-coupled, so MT-II raises cyclic AMP wherever it binds, and it binds essentially everywhere. In the melanocyte, cyclic AMP activates protein kinase A, which phosphorylates CREB and drives transcription of MITF, the master melanocyte transcription factor. MITF then upregulates tyrosinase, TYRP1 and DCT, and the pigment output shifts from red-yellow phaeomelanin toward brown-black eumelanin. That is why the colour is real melanin with genuine photoprotective capacity rather than a stain, and it is also why the tan takes one to two weeks to appear: you are waiting on transcription, protein synthesis and melanosome transfer to keratinocytes, not on a chemical reaction. It is also why people with loss-of-function MC1R variants - the classic red-haired, freckled phenotype - respond poorly. Their receptor is the thing you are trying to agonise. Centrally, MC4R and MC3R activation in the hypothalamus produces the same medial preoptic dopaminergic and oxytocinergic outflow that drives PT-141's sexual effect, plus appetite suppression through the arcuate POMC-MC4R satiety pathway and the yawning and stretching complex that is a signature of melanocortin agonism across species. The unavoidable point is that these are one drug hitting five receptors. You cannot dose the tan without dosing the nausea, the erections and the appetite loss, because there is no selectivity to exploit. The nausea does attenuate over one to two weeks, and that attenuation is receptor-level desensitisation at the brainstem rather than the drug wearing off, which is why people who push through the first week find week three unremarkable at the same dose.

The failure that ends up in a journal is melanoma or eruptive naevi. Causation is not proven, the case reports are individually unconvincing, and the biological story - stimulating melanocytes while masking colour change - is not far-fetched. The failure that ends up in an emergency department is rhabdomyolysis, usually with a high dose and an unverified vial. The failure that ends up on a forum is the first-dose experience: 1 mg straight in, six hours of nausea, flushing and a violent priapic episode at three in the morning. The quiet failure nobody notices is the surveillance one, where somebody with forty moles darkens all of them and now has no baseline to compare against. Get the photographs first. There is also a purity failure mode specific to this compound: MT-II is one of the most counterfeited peptides on the grey market precisely because the effects are so obvious that a partially degraded vial still flushes you, and flushing gets read as proof of potency.

1. 100 mcgDoses 1 to 3 — Yes, 100 mcg, regardless of what the dosing chart on the vendor site says. This tells you whether you are a heavy flusher and a heavy vomiter before you find out the hard way.
2. 250 mcgDoses 4 to 7 — Evening dosing so you can sleep through the flush. Nausea should already be noticeably less than at the same relative intensity on dose one.
3. 500 mcgWeek 2 to end of loading — The workhorse loading dose. Combine with modest, deliberate UV exposure - the peptide needs a stimulus and it is not sunscreen.
4. 1 mgMaintenance, from week 3 or 4 — One or two doses a week at up to 1 mg holds the colour. Survey data have adverse events roughly doubling above 1 mg per administration, so there is no reason to go higher.

• MC1R — Sub-nanomolar to low nanomolar in the original medicinal chemistry work, but no specific value was resolved here.

  Melanocyte pigmentation via cyclic AMP, PKA, CREB and MITF, shifting synthesis toward eumelanin. Also drives cutaneous vasodilation and mast cell activation, which is the flushing.

• MC3R

  Hypothalamic energy balance and part of the sexual motivation signal.

• MC4R

  The libido, spontaneous erection, appetite suppression and nausea receptor, all at once. Also the receptor behind the yawning and stretching.

• MC5R

  Sebaceous and exocrine gland receptor. Likely responsible for oilier skin and the occasional acne flare in the loading phase.

• MC2R (ACTH receptor)

  Minimal - MC2R responds essentially only to ACTH, so MT-II does not meaningfully stimulate cortisol. This is worth stating because it is a common forum worry that is not real.

• Melanotan-II pilot phase 1 clinical study (University of Arizona) 1 · 1996

  Safety and pigmentary response to subcutaneous melanotan-II in male volunteers. Produced dose-dependent tanning, and reported the stretching and yawning complex correlating with the onset of spontaneous penile erections - the observation that started the entire sexual-medicine branch of melanocortin research.

• Melanotan II in men with psychogenic erectile dysfunction, double-blind placebo-controlled crossover 2 · 1998

  Erection measured by RigiScan after subcutaneous MT-II versus placebo in men with psychogenic erectile dysfunction. MT-II initiated erections at a substantially higher rate than placebo.

• Alpha-MSH analogue in men with organic erectile dysfunction 2 · 2000

  Penile erection and sexual desire in men with organic erectile dysfunction. Confirmed the effect extends beyond the psychogenic group and explicitly measured desire, not just rigidity.

Flushing and nausea appear 30 to 90 minutes after the first few injections and are usually done within a few hours. Spontaneous erections in men typically start in the first week of loading and are the effect people least expect to be as prominent as it is. Appetite suppression is noticeable within days. Visible pigment change lags everything else by one to two weeks because it depends on transcription and melanosome transfer, and it deepens over three to four weeks of loading. Nausea and flushing attenuate substantially by week two to three at the same dose. Colour fades over roughly four to eight weeks after stopping, tracking normal keratinocyte turnover, which is why maintenance dosing exists at all.

MT-II plus PT-141 is the same drug twice and should not be done. MT-II plus Melanotan I is also redundant for pigmentation, though people occasionally run MT-I for colour and keep a low MT-II dose for the sexual effect, which at least has a coherent logic. The genuinely important stack is MT-II plus UV, and it is the one people get wrong: the peptide lowers the UV dose needed to trigger pigmentation, it does not raise the UV dose your skin can survive. People load MT-II, feel protected, and burn badly in week one. Combining with isotretinoin, tetracyclines or any other photosensitiser is worse for the same reason - the tan reads as protection while the drug is still sensitising you. Stacking with a GLP-1 agonist stacks two independent appetite-suppression mechanisms, and the nausea is additive and unpleasant. If you take finasteride or any other drug you are watching your skin on, note that MT-II darkens everything and makes any future dermatological assessment harder.

Against Melanotan I, MT-II is cheaper, more potent per milligram for pigmentation and vastly dirtier - MT-I gives you the colour without the nausea, erections or appetite loss, at several times the price. If you want only a tan, MT-I is the better molecule and MT-II is the one you can afford. Against PT-141, MT-II gives you the sexual effect plus pigmentation you may not want; PT-141 is the deamidated version engineered to give the sexual effect alone. Against sunbeds, MT-II reduces the UV dose you need for a given colour, which is a genuine harm-reduction argument on paper, but it also stimulates melanocytes pharmacologically and obscures the visual changes used to catch melanoma early, so the net risk position is honestly unresolved rather than favourable. Nobody has run the study that would settle it, and it is unlikely anybody ever will.

$10–$40/month. 10 mg vials commonly sell for 25 to 60 dollars. A full loading month at 250 to 500 mcg daily plus maintenance uses roughly one to one and a half vials, so most people spend less per month on MT-II than on the sunscreen they should also be using. The cheapness is part of why it is so widely used and so widely counterfeited.

• ?There is no published human pharmacokinetic dataset for MT-II beyond the 1996 pilot work. Volume of distribution, clearance, protein binding and elimination route are all genuinely unknown, and every number here that is absent is absent because it does not exist rather than because I could not find it.
• ?The one-hour half-life carried in the Core record is a widely repeated figure that I could not trace to a primary human pharmacokinetic study in this session.
• ?Receptor affinities at MC1R through MC5R are published in the Hruby and Hadley medicinal chemistry literature but I did not resolve specific Ki values here.
• ?The 2025 oral mucosal melanoma case associated with nasal-spray melanotan referenced in the Core record was not independently verified in this session.
• ?Whether the melanoma association is causal is unresolved and probably unresolvable. Users of tanning peptides also use sunbeds and have sun-seeking behaviour, which is a confounder no case series can remove.
• ?The 70 percent mole-darkening figure comes from user survey data rather than a controlled study.

• Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study Dorr RT, Lines R, Levine N, Brooks C, Xiang L, Hruby VJ, Hadley ME, Life Sciences, 1996 · PMID 8637402

  The founding human study. Establishes both the tanning and, almost as an aside, the erections.

• Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study Wessells H, Fuciarelli K, Hansen J, Hadley ME, Hruby VJ, Dorr R, Levine N, The Journal of Urology, 1998 · PMID 9679884

  The first properly controlled demonstration that a melanocortin agonist produces erections in humans.

• Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunction Wessells H, Levine N, Hadley ME, Dorr R, Hruby V, Urology, 2000 · PMID 11018622

  Extends the finding to organic erectile dysfunction and measures desire separately from rigidity.

• Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II Wessells H, Gralnek D, Dorr R, Hruby VJ, Hadley ME, Levine N, International Journal of Impotence Research, 2000 · PMID 11035391

  The best single summary of what the academic MT-II human work actually showed, written by the people who did it.

• Eruptive melanocytic naevi following melanotan injection Cousen P, Colver G, Helbling I, British Journal of Dermatology, 2009 · PMID 19575725

  The dermatology counterweight. New moles erupting after injection is not a theoretical concern, and it is the reason a dated baseline mole map is non-negotiable.