Melanogenesis without UV exposure [1]
Demonstrated increases in melanin density and skin darkening in human studies of melanotan analogues — the effect is real and reproducible.
PrecisePep/Peptide Library/Melanotan-2
Aesthetic & Melanocortin
Melanotan-2
MT-2 · MT-II · melanotan II
A non-selective melanocortin agonist that tans skin, suppresses appetite and causes erections — because it hits four receptors at once and cannot be told which one you wanted.
00 Overview
Melanotan-2 works, and that is the problem. It is a cyclic analogue of α-melanocyte stimulating hormone that agonises the melanocortin receptor family without selectivity. MC1R agonism drives eumelanin synthesis and tanning. MC4R agonism suppresses appetite and produces erections. MC3R and MC5R contribute effects that are less well characterised. A user wanting a tan gets all of it.
The regulatory history is unusual: the compound never completed development, but a related molecule did. Afamelanotide (Scenesse) is an MC1R-selective analogue approved for erythropoietic protoporphyria, and bremelanotide (Vyleesi) — an MT-2 metabolite — is approved for hypoactive sexual desire disorder. The non-selective parent is the one still circulating unapproved.[1]
Multiple national regulators, including in the UK, Australia and across the EU, have issued explicit safety warnings about melanotan products, citing unlicensed status, contamination, and reports of adverse effects including changes in moles.[3] That is a rare level of specific official attention for a research peptide.
The mole problem
MT-2 darkens existing naevi and has been associated in case reports with new and changing pigmented lesions, and with melanoma diagnosed during or after use. Causation is not established. What is established is that the compound makes moles change appearance — which is exactly the clinical signal dermatologists use to detect melanoma early. Even if MT-2 causes nothing, it degrades the detection signal.
// Mechanism of action
MC1R — pigmentation. Agonism on melanocytes stimulates eumelanin synthesis, producing tanning without ultraviolet exposure. This is the intended effect and the best-characterised one.
MC4R — appetite and erectile function. Central MC4R agonism suppresses food intake and triggers erections through hypothalamic and spinal pathways. Both are unavoidable consequences of a non-selective agonist, whether or not they were wanted.
MC3R and MC5R. MC3R contributes to energy homeostasis; MC5R affects exocrine gland function including sebaceous secretion — the plausible route to reported acne and oiliness.
Why selectivity matters. Afamelanotide is MC1R-selective and produces pigmentation without the appetite and erectile effects. That the selective version reached approval and the non-selective one did not is the clearest possible statement about which profile is clinically acceptable.
Nausea. Central melanocortin agonism is emetic. It is dose-related, near-universal on first exposure, and typically the reason people start low.
01 Reported benefits
Effects that have been reported. A study-tier entry means a result was published — not that the effect is established, reproducible, or transferable from a rodent to a person.
Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.
Erectile response in erectile dysfunction studies [2]
Human trials of MT-2 demonstrated erectile responses including in psychogenic ED, and this line of work led to bremelanotide.
Appetite suppression [1]
Central MC4R agonism reduces food intake — consistent across models and reported in humans.
Selective relatives reached approval [1]
Afamelanotide (MC1R-selective) is approved for erythropoietic protoporphyria; bremelanotide, an MT-2 metabolite, is approved for HSDD. The selective molecules made it; the non-selective one did not.
Photoprotection is partial at best [1]
Increased eumelanin offers some UV protection, but MT-2 does not confer sunscreen-equivalent protection and users frequently behave as though it does.
Unproven — inference onlyExtrapolated from a known mechanism, receptor profile, or adjacent compound class. Biologically plausible but not directly demonstrated for this compound in this context.
Reduced UV exposure by satisfying the desire to tan
The harm-reduction argument. It assumes users then avoid sun, which community reports do not support — many report tanning more readily and therefore sunbathing more.
Fat loss via MC4R
A real mechanism, and the reason setmelanotide (an MC4R agonist) is approved for specific genetic obesity syndromes. Not a use MT-2 has been developed for.
Libido enhancement
Well-supported mechanistically, and the basis of an approved derivative. With MT-2 it arrives alongside everything else.
Concern: melanoma and pigmented lesion change [3]
Case reports describe new and changing naevi and melanoma diagnosed in users. Causation is unestablished; the confounding of dermatological surveillance is not in doubt.
Uncontrolled reportsAggregated from research-community logs, forums, vendor literature and self-reported experience. Uncontrolled, unverified, subject to placebo, polypharmacy and product-purity confounds. Lowest evidentiary weight.
Pronounced tanning within 2–4 weeks
The effect is reliable and is why the compound persists despite everything else on this page.
Spontaneous erections
Near-universal in men, frequently unwanted and often inconveniently timed.
Nausea and flushing after injection
Near-universal on first doses, generally settling with continued use and lower doses.
Darkening of existing moles and freckles
Consistently reported. Users generally treat this as cosmetic; dermatologically it is the signal that matters.
Appetite suppression
Reported as a welcome side effect, and it is a genuine MC4R effect.
02 Adverse effects & risks
Adverse effects, contraindications and unknowns. The grey-market tier is where under-reporting is worst: uncontrolled use produces no systematic safety surveillance at all, so absence of a reported harm is not evidence of safety.
Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.
Nausea, flushing and spontaneous erections [1][2]
The dominant adverse effects across human studies of MT-2, all dose-related and all direct consequences of non-selective melanocortin agonism.
National regulator safety warnings [3]
Multiple regulators have issued explicit public warnings about melanotan products covering unlicensed status, product contamination and adverse reports including mole changes.
Case reports of melanoma and changing naevi [3]
Published case reports describe melanoma diagnosed in melanotan users and eruptive or changing pigmented lesions. Small numbers, no causal demonstration, and a coherent biological concern.
Priapism [2]
Reported, and a urological emergency requiring immediate treatment to avoid permanent damage.
Rhabdomyolysis and renal injury case reports [3]
Isolated but published, and a reminder that the adverse-effect range extends beyond the predictable melanocortin effects.
Unproven — inference onlyExtrapolated from a known mechanism, receptor profile, or adjacent compound class. Biologically plausible but not directly demonstrated for this compound in this context.
Interference with melanoma detection
Independent of whether MT-2 causes anything, darkening and changing moles makes clinical surveillance harder. Anyone using it should have a dermatological baseline first.
Product contamination [3]
Regulators have specifically cited contamination in seized melanotan products. This is a documented supply problem, not a generic caution.
Cardiovascular effects from melanocortin agonism
Melanocortin signalling affects blood pressure and heart rate; bremelanotide carries a transient blood-pressure effect in its labelling.
Unknown long-term consequences of chronic pigmentary stimulation
Sustained melanocyte stimulation over years has no characterisation.
Uncontrolled reportsAggregated from research-community logs, forums, vendor literature and self-reported experience. Uncontrolled, unverified, subject to placebo, polypharmacy and product-purity confounds. Lowest evidentiary weight.
Nausea, sometimes severe, on early doses
The most common complaint by a wide margin.
Unwanted erections
Universally reported by male users.
New freckles and darkened moles
Consistently reported and consistently under-weighted.
Facial flushing and lethargy
Common in the hours after dosing.
Acne and increased skin oiliness
Plausibly MC5R-mediated via sebaceous gland stimulation.
03 Dosing ranges
Figures below are documented, not recommended. Study ranges come from published protocols in the stated model; grey-market ranges are what the research community reports using and carry no safety validation of any kind.
Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.
Unproven — inference onlyExtrapolated from a known mechanism, receptor profile, or adjacent compound class. Biologically plausible but not directly demonstrated for this compound in this context.
Loading then maintenance
Higher-frequency dosing to establish pigmentation, then infrequent maintenance. The structure is coherent given that melanin persists after dosing stops.
Evening dosing
Community convention to sleep through the nausea and flushing. Practical rather than pharmacological.
Minimise total exposure
Given that the desired effect persists and the risks are cumulative and pigmentary, the lowest total dose achieving the tan is the coherent target.
Uncontrolled reportsAggregated from research-community logs, forums, vendor literature and self-reported experience. Uncontrolled, unverified, subject to placebo, polypharmacy and product-purity confounds. Lowest evidentiary weight.
250 mcg daily (loading)
The common starting figure, deliberately low because of nausea.
500 mcg – 1 mg daily during loading
Escalated once nausea settles, typically for two to four weeks until the desired pigmentation is reached.
500 mcg – 1 mg once or twice weekly (maintenance)
The step-down phase, since melanin persists.
| Phase | Dose | Frequency | Duration |
|---|---|---|---|
| Initiation | 250 mcg | Daily, evening | 3–7 days |
| Loading | 500 mcg – 1 mg | Daily, evening | 2–4 weeks |
| Maintenance | 500 mcg – 1 mg | 1–2× weekly | Ongoing |
04 Synergy & interactions
Combination effects. Almost no peptide combination has been studied as a combination in humans; stack logic is overwhelmingly mechanistic inference and community practice. Each linked compound has its own page.
Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.
No combination studies exist
No study has combined MT-2 with another research compound.
Unproven — inference onlyExtrapolated from a known mechanism, receptor profile, or adjacent compound class. Biologically plausible but not directly demonstrated for this compound in this context.
With incretin agonists
MC4R-mediated appetite suppression on top of incretin appetite suppression. Additive intake reduction with additive nausea, and no data.
With PT-141 — redundant and additive
PT-141 (bremelanotide) is an MT-2 metabolite acting on the same receptor family. Running both stacks melanocortin agonism with no added mechanism.
With KPV — opposite ends of the same hormone
KPV is the anti-inflammatory α-MSH fragment stripped of melanocortin potency; MT-2 is the full non-selective agonist. Instructive to compare, not to combine.
With copper peptides for skin
Common in aesthetic stacks. No interaction data.
Uncontrolled reportsAggregated from research-community logs, forums, vendor literature and self-reported experience. Uncontrolled, unverified, subject to placebo, polypharmacy and product-purity confounds. Lowest evidentiary weight.
Aesthetic pillar of the 15-Compound Matrix
MT-2 is the sole compound in the aesthetic and pigmentation matrix.
Combined with sunbed or sun exposure
Widely practised to accelerate the tan, and it compounds the UV exposure question the compound was supposed to reduce.
05 Protocols
Whole schedules — dosing, titration, cycle length, and off-time — as documented in trials, as proposed from mechanism, and as circulated in the research community. Reproduced for study and comparison only.
Highest confidenceReported in peer-reviewed literature, registered clinical trials, or regulatory filings. Note the model: much peptide literature is in vitro or rodent work, not human trial data.
No completed clinical protocol
Development did not proceed to approval for the non-selective compound.
Unproven — inference onlyExtrapolated from a known mechanism, receptor profile, or adjacent compound class. Biologically plausible but not directly demonstrated for this compound in this context.
Full-body dermatological mole mapping before and after
The single most useful precaution available for this compound, and it directly addresses the one risk that is both plausible and detectable.
Minimum effective total exposure
Load only until the desired pigmentation is reached, then maintain infrequently.
Uncontrolled reportsAggregated from research-community logs, forums, vendor literature and self-reported experience. Uncontrolled, unverified, subject to placebo, polypharmacy and product-purity confounds. Lowest evidentiary weight.
Load then maintain, seasonally
The standard community pattern, run ahead of summer or travel.
15-Compound Matrix — Q4 aesthetic tier
Placed last in the phased matrix, after the metabolic, regenerative, immune and neuro-cognitive phases.
05b Condition-specific interest
This is the only page in this library where the published human literature consists mainly of case reports of harm. There are no efficacy trials to weigh against them. That asymmetry is the honest summary of the compound, and everything below follows from it.
No approval, no trial
Melanotan-2 is not approved anywhere and has been the subject of explicit safety warnings from regulators in the UK, Ireland, Australia, Sweden, Norway and elsewhere. Those warnings were issued because of the case reports described below, not as a formality. Nothing on this page is a recommendation, and the tanning claim is not the thing to weigh — the surveillance problem is.
The disease itself, its early-detection rules and the reason the highest-risk group is also the group this compound is marketed to hardest are covered under melanoma & skin cancer.
Study — case reports, and they are what exists
Naevus change and melanoma — the published human literature
Pathophysiology
Melanotan-2 is a non-selective melanocortin agonist. MC1R activation stimulates melanocytes, and melanocytes are the cells melanoma arises from.
Mechanistic rationale
The dermatological literature contains: eruptive naevi and darkening of pre-existing naevi within 24 hours of a single injection; eruptive dysplastic naevi following use; rapidly changing moles with histology ranging from benign to severely dysplastic in people injecting melanotan; and case reports of melanoma arising in existing moles during or shortly after use, including melanoma in situ. Case reports cannot establish causation and there is no cohort study here. They also cannot be dismissed, and they are the only human data this compound has.
Community reports
Mole darkening is so consistently reported by users that it is treated as confirmation the compound is working. It is the same observation the case reports describe.
Components carrying the argument: MC1R agonism on melanocytes
Actionable warning
The surveillance problem — the part that matters most
Pathophysiology
Melanoma is detected early by noticing that a mole has changed — in asymmetry, border, colour, diameter or evolution. Early detection is the single largest determinant of survival: thin melanoma is usually curable by excision, thick melanoma frequently is not.
Mechanistic rationale
Melanotan-2 darkens moles. It therefore degrades the signal that skin cancer detection depends on, in a way that is diffuse, affects every lesion at once, and cannot be distinguished from a genuine change without a dermatologist and probably a dermatoscope. Even if the compound never caused a single melanoma, it would still make the melanomas that occur anyway harder to catch early. That argument holds regardless of where the causation question lands.
Community reports
Users describe moles becoming darker and new ones appearing, and generally interpret both as cosmetic. Baseline mole mapping before any use, and dermatological review of anything that changes, is the only sensible response — and is not what happens.
Components carrying the argument: Not pharmacology — loss of a diagnostic signal
Theorized — and the framing is backwards
Tanning and photoprotection — the claimed benefit
Pathophysiology
Melanin provides some protection against UV-induced DNA damage, and the argument for a tanning peptide is that it produces that protection without the UV exposure that normally induces it.
Mechanistic rationale
A darker skin tone does confer some photoprotection. But the practical effect of a tanning compound is more sun exposure, not less — people who tan more easily spend more time in the sun and burn less, which removes the feedback signal that limits exposure. Induced pigmentation is also not equivalent to a sunscreen, and it does not prevent UV-induced DNA damage reliably. The compound most associated with melanoma case reports also encourages the behaviour most associated with melanoma.
Community reports
The tanning effect is real and is the reason people use it. Sunbed and sun exposure alongside it is the norm rather than the exception, and is frequently described as necessary to "activate" the tan.
Components carrying the argument: MC1R-mediated melanogenesis
Study — the side effect that became a drug
Sexual effects and priapism
Pathophysiology
MC3R and MC4R agonism in central pathways produces sexual arousal, which is unrelated to the pigmentary effect and mediated by different receptors.
Mechanistic rationale
Spontaneous erections during early tanning research were the observation that led to PT-141 being developed as a separate drug for sexual dysfunction. Melanotan-2 causes priapism — a prolonged erection that is a urological emergency and can cause permanent erectile tissue damage if not treated within hours. This is the mechanism PT-141 was refined toward and Melanotan-2 delivers without any of the dose control.
Community reports
Spontaneous erections are among the most commonly reported effects and are usually treated as a bonus. Priapism lasting more than four hours requires emergency care, not waiting.
Components carrying the argument: MC3R / MC4R agonism
Theorized — real mechanism, incidental use
Appetite suppression and other melanocortin effects
Pathophysiology
MC4R signalling in the hypothalamus is a core component of appetite regulation — loss-of-function MC4R mutations are the most common monogenic cause of obesity, and setmelanotide is an approved MC4R agonist for specific genetic obesity syndromes.
Mechanistic rationale
Appetite suppression from Melanotan-2 is genuine and mechanistically well grounded. It is also non-selective agonism of a receptor family with pigmentary, cardiovascular, sexual and appetite effects at once, which is precisely the problem that selective agents were developed to solve.
Community reports
Reduced appetite is commonly reported and occasionally becomes a secondary reason for use. Nausea, facial flushing and yawning after dosing are also near-universal early effects.
Components carrying the argument: MC4R agonism
Study — scattered, and worth knowing
The other case reports
Pathophysiology
Non-selective agonism across a receptor family produces effects wherever those receptors sit.
Mechanistic rationale
Beyond the melanocytic literature, published case reports associated with melanotan use include rhabdomyolysis, renal injury and encephalopathy. These are individual reports rather than a characterised risk profile — which is itself the point: for a compound with no trials, case reports are the entire safety database, and a sparse database reflects sparse reporting rather than sparse risk.
Community reports
Not widely known. The absence of systematic safety data is generally read as an absence of problems.
Components carrying the argument: Non-selective melanocortin agonism
| Question | Position |
|---|---|
| Approved anywhere? | No — and explicitly warned against by several regulators |
| Human efficacy trials? | None |
| Human safety literature? | Case reports — naevi, dysplastic naevi, melanoma |
| Fastest documented naevus change | 24 hours after a single injection |
| Surveillance | Darkens every mole — degrades early detection |
| Priapism | Documented — a urological emergency over 4 hours |
| Photoprotection | Partial at best; in practice increases sun exposure |
| Refined into | PT-141 — for the sexual effect, with dose limits |
What actually has evidence for these conditions
For skin cancer prevention: sun protection, avoiding sunbeds entirely, and knowing your own moles. Baseline photography or mole mapping is worthwhile for anyone with many naevi, a family history, or fair skin — and is essential for anyone who has used this compound, because the baseline has been altered. Any mole that changes warrants a dermatologist.
For a tan: topical dihydroxyacetone self-tanning products colour the stratum corneum, do not involve melanocytes, do not require injection, and are among the few cosmetic products with an uncontroversial safety record. They provide no photoprotection, but neither reliably does an induced tan.
For sexual dysfunction: PDE5 inhibitors, an ED workup that takes the cardiovascular signal seriously, and PT-141 — which is the approved, dose-limited refinement of the effect people are seeking here.
06 Handling, reconstitution & storage
Physical-chemistry reference for laboratory handling of the lyophilised material. Reproduced so that stability and concentration mathematics can be studied — see the calculator for the arithmetic and the reconstitution guide for sterile technique.
Reconstitution
Supplied lyophilised, commonly 10 mg per vial. At 500 mcg daily a 10 mg vial is twenty days.
Storage
Lyophilised: refrigerated or frozen, protected from light. Reconstituted: 2–8 °C.
Common vial sizes
Commonly 10 mg lyophilised vials.
Stability notes
A cyclic peptide with reasonable stability. Note that regulators have specifically cited contamination in seized melanotan products, which is a supply concern rather than a stability one.
07 Legal & regulatory status
Regulatory status changes and differs by country. This is a summary for orientation, not legal advice — check your own jurisdiction.
Not approved anywhere. Melanotan-2 has never been approved for human use. Multiple national regulators have issued explicit safety warnings about melanotan products and, in several jurisdictions, sale is actively enforced against.
Two related molecules are approved: afamelanotide (Scenesse), an MC1R-selective analogue for erythropoietic protoporphyria, and bremelanotide (Vyleesi), an MT-2 metabolite for hypoactive sexual desire disorder. Neither approval extends to melanotan-2.
Regulatory update — current as at August 2026
Melanotan II is scheduled for review by the FDA's Pharmacy Compounding Advisory Committee before the end of February 2027, alongside Melanotan II, LL-37 (cathelicidin), Dihexa acetate and PEG-MGF — whichever of those is not this compound.
This follows the FDA's April 2026 restructuring of the Section 503A categories and the July 2026 meeting at which six peptides (BPC-157, KPV, TB-500, MOTS-c, Semax and Epitalon) were recommended for the Bulks List and one (emideltide/DSIP) was not. Nothing has been decided for Melanotan II.
A PCAC recommendation is not an approval, and the 503A Bulks List is not a drug approval either. It is also worth knowing that July 2026 was the second round: across two sittings in October and December 2024 the same committee reviewed seven substances — among them ipamorelin, kisspeptin-10, AOD-9604, CJC-1295 and thymosin alpha-1 — and rejected all seven. Two separate things are being conflated in almost every write-up of the 2026 decision:
- The vote is advisory. PCAC recommendations are non-binding. The pathway from here runs: removal from Category 2 (done, April 2026) → PCAC recommendation (done, July 2026) → placement in Category 1 through notice-and-comment rulemaking, which commonly takes eight to twelve months → and the HHS Secretary must sign off on any addition to the list. Nothing is lawfully compoundable on the strength of the vote alone.
- Even a successful listing would not make these approved drugs. Inclusion on the 503A Bulks List permits a licensed compounding pharmacy to use the substance in a compounded preparation for an individual patient with a prescription. It says nothing about the compound being demonstrated safe and effective — no efficacy trial is required, and none of these has one.
- It would not legitimise research-chemical supply. A compounding pathway runs through a licensed pharmacy and a prescriber. Grey-market vials labelled "research use only" are not that, and nothing in this decision changes their status.
Regulatory and trial claims re-checked against primary sources on 16 August 2026. Checked: naevus, dysplastic naevi and melanoma case-report literature. Approvals, trial readouts and compounding decisions move faster than anything else on this page — a date here means someone looked, not that nothing has changed since.
Anti-doping
Athletes subject to WADA, USADA, UKAD, NCAA or military testing should assume any peptide is prohibited unless they have verified otherwise against the current WADA Prohibited List. Several classes here (growth-hormone secretagogues, TB-4 analogues, metabolic modulators) are explicitly named. Check the current list — it is republished annually.
§ Sources & further reading
Links resolve to PubMed records, trial registries, publisher pages or primary documents. Where a body of work rather than a single paper is cited, the link opens a PubMed query so the full result set — including newer papers than this page — can be reviewed. Verify every claim against the primary source before relying on it.
- PubMed: melanotan II — melanocortin agonism, melanogenesis and clinical studies (live query)Database or literature search
- PubMed: melanotan II and bremelanotide in erectile dysfunction (live query)Database or literature search
- PubMed: melanotan — melanoma, changing naevi, adverse effects and case reports (live query)Database or literature search
- UK MHRA — public safety information on unlicensed melanotan productsRegulatory / official document
Reminder
For educational and research reference only. Nothing on this site is medical advice, a recommendation, or an instruction to administer any substance to a human being. Every figure on this page is a record of what has been reported, not a recommendation. Full disclaimer.