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Educational reference only. Nothing on this page constitutes medical advice or encourages personal use of this compound. Always consult a qualified healthcare provider before any decision involving your health.
Human Phase I · MT-II
Melanotan II is a compound that genuinely works for tanning, genuinely produces erections and sexual arousal, and genuinely raises questions about melanoma that the evidence has not resolved. It is not a fringe compound with no activity — it has Phase I human data, a coherent receptor mechanism, and a pharmacological lineage that produced an FDA-approved drug. It is also one of the most seriously safety-flagged compounds in this book.
The compound's story resolves here: the University of Arizona team was right that MC1R activation produces tanning. They were also right that non-selective activation of MC3R and MC4R is unavoidable with MT-II. The molecule that was designed to make tanning safer may introduce its own skin cancer risk pathway through MC1R-driven melanocyte proliferation — or it may not, because the evidence is confounded by UV-seeking behavior in the same user population. The melanoma question will not be resolved without a prospective controlled study that has not been done and likely will not be done. In this uncertainty, the practical rule is straightforward: anyone with elevated melanoma risk should not use this compound; anyone who uses it needs active dermatological surveillance.
The most remarkable thing about Melanotan II is that the same molecule's unexpected side effects eventually gave the world an FDA-approved sexual dysfunction drug. The 'problems' with MT-II became the product.
In the early 1980s, dermatologists at the University of Arizona were thinking about skin cancer prevention from an unusual angle. UV radiation causes sunburn and skin cancer — but humans deliberately seek UV exposure for tanning. The behavioral driver of that UV-seeking was the cosmetic desire for tanned skin. Mac Hadley and Victor Hruby reasoned: if you could produce tanning without UV exposure, you might reduce UV-seeking behavior and therefore reduce skin cancer incidence. The target was the melanocortin system — specifically MC1R on skin melanocytes, which when activated by endogenous alpha-MSH drives eumelanin production and natural tanning. Their compound, Melanotan II, was a synthetic cyclic analog of alpha-MSH designed to be more potent and longer-lasting than the native hormone.
The Phase I clinical trial in 1996 (Dorr [1] et al., Life Sciences) produced the intended result: Melanotan II darkened skin in subjects with and without UV exposure. It produced real tanning. It also produced three things nobody had planned for: significant nausea, facial flushing, and in male subjects, spontaneous penile erections. These were dose-dependent. They were not rare. And they were immediately recognized as pharmacologically informative: nausea and the cardiovascular flushing were MC3R/MC4R-mediated central effects; the erections were unambiguously MC4R-driven hypothalamic activation of the sexual arousal pathway. Within a decade, a fragment of MT-II's receptor binding pharmacology had been isolated and developed into PT-141 (bremelanotide), the first non-hormone, centrally acting drug for female hypoactive sexual desire disorder. Bremelanotide received FDA approval in 2019. It is MT-II's pharmacological child.
THE CENTRAL TENSION
Melanotan II is a molecule that does three things at once that were never designed to go together: it tans your skin (MC1R), gives you an erection and heightened sexual arousal (MC4R), and suppresses your appetite and raises your blood pressure (MC3R/MC4R sympathetic output). The non-selectivity that made it a problematic drug candidate made it one of the most pharmacologically interesting compounds in the melanocortin literature. It also made it enormously appealing to a community seeking a cosmetic edge — people who wanted a tan, an erection, or appetite suppression discovered they could get all three simultaneously. The central tension of MT-II's story is that the molecule is genuinely active and genuinely dangerous at the same time, and that its most alarming safety signal — the melanoma question — remains genuinely unresolved even after decades of use and case reports.
⛔ ABSOLUTE CONTRAINDICATIONS
1. Personal or family history of melanoma. MC1R stimulation promotes melanocyte proliferation; the mechanistic risk in melanoma is real regardless of whether causality in the case reports is proven. 2. Dysplastic nevus syndrome or >50 moles. Elevated baseline melanoma risk + MC1R stimulation = unacceptable risk. 3. Active or recent skin cancer of any type. 4. Active malignancy of any type (general caution for any angiogenic or proliferative peptide). These are not 'use with caution' scenarios. They are hard stops.
Nausea: most common; onset 30-90 minutes post-injection; peaks at 60-90 minutes; resolves within 2-4 hours; worst in loading phase days 1-5, typically subsides significantly by week 2; mechanism is MC4R central emetic pathway activation. Facial flushing and warmth: MC5R exocrine stimulation + MC4R vasodilation; typically lasts 30-60 minutes. Spontaneous erections (males): MC4R; occur without sexual stimulation; can be embarrassing or unwanted if not anticipated; typically resolve within 1-2 hours without intervention. Appetite suppression: MC3R/MC4R; many users consider this a benefit rather than a side effect; reduced hunger particularly in the 2-4 hours post-injection. Fatigue and sedation: commonly reported in the loading phase; mechanism unclear; resolves with continued use.
Mole darkening: MC1R activation darkens existing nevi (moles); this is expected and pharmacologically consistent. New mole formation: reported by community users; MC1R stimulation of previously quiescent melanocyte clusters. Freckle darkening and proliferation: similar mechanism. Injection site hyperpigmentation: localized MC1R activation from repeated injections at the same site; rotate sites. Nail melanonychia: melanin deposition in the nail matrix causing black-brown nail discoloration; grows out over months after stopping. These skin changes are not inherently dangerous, but they complicate dermatological assessment — a new mole on someone using MT-II may be MT-II-induced benign proliferation or may be melanoma. Regular dermatological screening is mandatory for any MT-II user. Any new mole, changing mole, or skin lesion that develops during or after a MT-II cycle should be evaluated by a dermatologist before resuming use.
Priapism: prolonged painful erection lasting >4 hours; medical emergency requiring urological intervention; can cause scarring and permanent erectile dysfunction. Risk is real and documented; seek emergency care immediately if erection lasts >2 hours and will not resolve. At supratherapeutic doses. Rhabdomyolysis: case report (Nelson 2012) in a male who injected 6 mg (approximately 12x the standard 0.5 mg loading dose); muscle breakdown with acute kidney injury. This occurred at a massively supratherapeutic dose; standard community doses have not produced this in published literature, but the case illustrates the danger of dose confusion or nasal spray overdosing. Renal infarction: multiple case reports; mechanism possibly MC4R-mediated sympathetic vasoconstriction reducing renal perfusion. Hypertensive crisis: at higher doses; MC4R sympathetic activation.
THE NASAL SPRAY IS THE HIGHEST-RISK DELIVERY FORMAT
Nasal sprays sold online as 'tanning nasal sprays' or 'Barbie drug' contain Melanotan II without sterility standards, without accurate dosing, without any quality control, and with poorly characterized bioavailability via the nasal route. Vial content analysis found 4.32-8.84 mg in vials claiming 10 mg. The same MC4R side effects occur via nasal route as SubQ. MHRA, multiple national health authorities, and dermatology societies have explicitly warned against all MT-II nasal spray products. The nasal format adds the risks of nasal mucosal exposure to an unsterile substance on top of the systemic melanocortin risks. If someone is going to use MT-II, the SubQ route with pharmaceutical-grade reconstituted powder is safer than a nasal spray by every measure. The nasal spray format should be avoided entirely.
The melanocortin receptors (MC1R–MC5R) are G-protein coupled receptors (GPCRs) activated by melanocortin peptides derived from POMC (pro-opiomelanocortin). The five subtypes have distinct tissue distributions and functions. Melanotan II binds all five with varying but generally high affinity, making it a pharmacological sledgehammer in a system built for precision. This non-selectivity is the defining pharmacological characteristic of MT-II and the source of its entire side effect profile.
Receptor
Primary Location
Function
MT-II Effect
Clinical Consequence
MC1R
Skin melanocytes
Eumelanin synthesis → tanning; photoprotection
Activates: ↑ melanin production, pigmentation without UV
Tanning; darkening of moles, freckles, nevi; new mole formation
MC3R
Hypothalamus, limbic system
Energy balance, appetite, inflammation modulation
Activates: appetite suppression, energy expenditure ↑
Reduced hunger; can produce weight loss at sustained doses; mood effects
MC4R
Hypothalamus, brainstem
Sexual arousal, appetite, sympathetic output
Activates: sexual arousal both sexes; spontaneous erections in males; sympathetic NS ↑
Erections (spontaneous), libido ↑; HR ↑ 8-15 bpm; SBP ↑ 6-12 mmHg; nausea
MC5R
Exocrine glands, skin
Sebaceous and exocrine secretion
Activates: exocrine gland stimulation
Facial flushing, warmth, increased sweating
When MT-II binds MC1R on melanocytes: adenylate cyclase activation → cAMP elevation → protein kinase A (PKA) activation → MITF (microphthalmia-associated transcription factor) upregulation → tyrosinase expression ↑ (rate-limiting enzyme in melanogenesis) → melanosome production and maturation → eumelanin synthesis and transport to surrounding keratinocytes → skin darkening. This cascade is identical to the pathway activated by natural sun exposure, but the triggering signal (MC1R activation) occurs without UV. The resulting tan is photoprotective — eumelanin absorbs UV radiation — which was the original drug concept.
MT-II crosses the blood-brain barrier (the cyclic analog structure improves BBB penetration vs linear alpha-MSH). In the hypothalamus, MC4R activation stimulates oxytocin release from paraventricular nucleus neurons — oxytocin projections to the spinal cord activate pro-erectile circuitry in the lumbosacral spinal cord. In males: nitric oxide-mediated corpus cavernosum dilation → erection, often occurring without sexual stimulation. In females: increased genital blood flow, heightened arousal sensitivity, and desire. This is precisely the mechanism that PT-141 (bremelanotide) was developed to harness selectively — without the tanning and cardiovascular effects that come from MT-II's additional receptor targets.
MC4R in the brainstem and hypothalamus regulates sympathetic nervous system output. A 2019 study in the Journal of Clinical Endocrinology & Metabolism documented that MC4R activation increases heart rate by 8-15 beats per minute and systolic blood pressure by 6-12 mmHg in normotensive subjects within 60-90 minutes of administration. This is not a side effect in the pharmacological sense — it is a direct receptor-mediated pharmacological action. For individuals with hypertension, cardiovascular disease, or who are taking antihypertensives, this predictable sympathetic activation represents a meaningful cardiovascular risk.
Feature
Melanotan I (Afamelanotide)
Melanotan II (MT-II)
PT-141 (Bremelanotide)
Structure
Linear 13-AA α-MSH analog
Cyclic 7-AA analog (Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-NH2)
Cyclic 7-AA; MT-II without the C-terminal amide; otherwise identical
Receptor selectivity
MC1R-selective
Non-selective: MC1R, MC3R, MC4R, MC5R
MC3R/MC4R-preferring; no significant MC1R at clinical doses
Tanning
Yes — primary indication
Yes — primary community use
No — no significant MC1R activity
Sexual arousal effect
No — MC1R only
Yes (MC4R) — pronounced; spontaneous erections in males
Yes (MC4R) — primary indication; approved for HSDD in women
Erections
No
Yes — often spontaneous, not stimulus-dependent
Yes — stimulus-dependent; less spontaneous
Appetite suppression
No
Yes (MC3R/MC4R)
Yes (MC4R)
CV effects
Minimal
Yes — HR and BP elevation (MC4R)
Yes — similar; hypertension most common adverse event in VYLEESI trials
FDA approval
Yes — Scenesse (EPP indication; SC implant)
No — not approved anywhere
Yes — Vyleesi (HSDD in premenopausal women; SC injection)
Nausea profile
Minimal at clinical doses
Significant — dose-dependent; peaks 30-90 min post-injection
Significant — most common adverse event in VYLEESI trials (40%)
Route
SC implant (pharmaceutical)
SubQ injection; nasal spray (unregulated)
SubQ auto-injector (pharmaceutical)
Melanotan II reached Phase I human trials and produced the tanning effect it was designed for. Development stopped not because it didn't work, but because it worked too broadly — the MC4R-mediated side effects could not be separated from the MC1R tanning benefit in the same molecule.
Dorr RT, Lines R, Levine N, Brooks C, Xiang L, Hruby VJ, Hadley ME. (1996). Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sciences. 58(20):1777-84. Design: dose-escalation Phase I; healthy male volunteers; MT-II 0.01 mg/kg subcutaneous; primary endpoints: tanning response, safety. Results: significant skin darkening at 0.01 mg/kg; all subjects experienced nausea and facial flushing; spontaneous penile erections occurred in all male subjects. This was the paper that established both MT-II's tanning efficacy and its MC4R pharmacology in humans. The erections were not a bug report — they were the pharmacological discovery that led directly to the PT-141 program. Grade B: Phase I human data with safety endpoints; small n; dose-escalation design; single institution.
A small number of additional Phase I/II studies evaluated MT-II primarily for the tanning indication. All confirmed: (1) melanogenesis and skin darkening at therapeutic doses; (2) nausea, flushing, and sexual arousal as consistent dose-dependent adverse effects; (3) no dose found at which MC1R tanning effects occurred without MC4R-mediated neurological effects. Development was discontinued not for lack of efficacy but because the non-selectivity precluded a clean regulatory path for the tanning indication.
Evidence
Grade
Finding
Dorr et al. 1996 (Life Sciences; Phase I; n=small)
B
Tanning confirmed at 0.01 mg/kg; spontaneous erections in all male subjects; nausea and flushing dose-dependent; foundational human data
MC4R cardiovascular study (J Clin Endocrinol Metab, 2019)
B
HR ↑ 8-15 bpm; SBP ↑ 6-12 mmHg within 60-90 min of MC4R activation; sympathetic output mechanism confirmed in humans
Melanoma case reports (Brennan 2017 [4] review: 4+ cases)
D
Melanoma during or after MT-II use documented in case reports; causality not established
Javed 2013 [2] (systematic review)
C
No conclusive evidence MT-II causes melanoma
Wensink 2021 [3] (review)
C
Increased melanoma risk in MT-II users probably explained by UV-seeking behavior confound
Rhabdomyolysis case (Nelson 2012) [6]
D
Single case; 6 mg dose (12x standard starting dose); likely overdose effect
Renal infarction case reports
D
Multiple case reports; mechanism unclear; sympathetic vasoconstriction plausible mechanism
Nasal spray vial analysis (pharmacovigilance study)
B
Vials contained 4.32-8.84 mg vs claimed 10 mg; significant underdosing common; no sterility standards
The most important unresolved safety question about Melanotan II: does it cause melanoma? After decades of use, the answer remains genuinely uncertain. Here is the evidence for each position.
For the concern: (1) MC1R activation on melanocytes stimulates proliferation of melanocytes and melanogenesis; this is the same cellular pathway that goes wrong in melanoma. (2) At least 4 case reports (documented in Brennan 2017 systematic review) describe melanoma during or shortly after MT-II use; some in individuals without prior UV exposure history. (3) MT-II users frequently report rapid development of new moles and darkening of existing nevi — exactly the changes dermatologists assess as melanoma warning signs. (4) The British Association of Dermatologists, MHRA, and Australian TGA have all issued explicit warnings about melanoma risk.
Against the concern: (1) Javed et al. 2013 systematic review concluded no conclusive evidence that MT-II causes melanoma — the case reports are insufficient to establish causality; correlation is not causation. (2) Wensink et al. 2021 review concluded that the observed increased melanoma risk in MT-II users can probably be explained by UV-seeking behavior: people who use MT-II for tanning are also more likely to use sunbeds and seek UV — the real melanoma risk factor. (3) MC1R activation produces eumelanin specifically — eumelanin is UV-protective and is associated with reduced rather than increased melanoma risk in normal physiology. (4) The PT-141 clinical trial program (same MC4R activity, no MC1R) has not shown melanoma signal — consistent with MC4R not being the carcinogenic driver.
The honest position: causality is unproven. The mechanism of concern is real. The confound (UV-seeking behavior in the same population) is also real. Anyone with elevated melanoma risk — personal or family history, dysplastic nevi, fair skin, excessive UV history — should not use MT-II. For the general community user, the melanoma risk is uncertain, the monitoring protocol (regular dermatological screening, immediate evaluation of any new or changing moles) is mandatory, and the risk-benefit calculation is individual. This is not a situation where the evidence cleanly resolves in either direction. Honest uncertainty is the appropriate position.
Standard MT-II vial: 10 mg lyophilized powder. Reconstitution: 2 mL bacteriostatic water → 5 mg/mL (5,000 mcg/mL). On a U-100 insulin syringe: 1 mg = 20 units; 0.5 mg = 10 units; 0.25 mg = 5 units. Store reconstituted vial refrigerated (2-8°C), protected from light; use within 28 days. Note: commercially sold vials have tested at 4.32-8.84 mg actual content vs claimed 10 mg — dose calculations based on labeled content may overestimate actual dose. Purchase from vendors with HPLC + mass spec COA, not just HPLC.
Day
Dose
Notes
Days 1-3
100-150 mcg (0.1-0.15 mL at 5 mg/mL)
Start low to assess nausea tolerance; inject 30-60 min before bed
Days 4-7
200-250 mcg
Titrate up if nausea manageable; continue UV or sunbed exposure
Days 8-14
250-500 mcg
Full loading dose; significant tanning should be visible by week 2
Maintenance
250-500 mcg 2-3x weekly
Sustain tan; continue UV; reduce to maintenance dose after loading
Melanotan II primes melanocytes for melanin production but does not activate them maximally without UV stimulus. Community consensus and clinical data agree: UV exposure — sunlight or controlled sunbed (10-20 minutes, 2-3x per week) — is required during the loading phase to achieve the tan. MT-II substantially reduces the UV dose required for the same tanning response, but UV is not fully replaced. MT-II without UV produces some darkening (particularly in darker skin types with higher baseline melanocyte activity), but meaningful tanning requires UV catalyst. This has an important implication: MT-II users are still exposing themselves to UV, and UV is the established primary melanoma risk factor. The 'sunless tanning' framing is inaccurate — it is more accurately 'reduced-UV tanning.'
The MT-II tan fades after stopping — typically over 3-6 months as melanin-containing keratinocytes turn over. Community users commonly report that re-loading requires lower doses than the initial loading phase, consistent with maintained melanocyte sensitization. The fade rate depends on UV exposure during maintenance — continued UV slows fade; no UV accelerates it. This creates a pattern of repeated cycles for those seeking a persistent tan, which increases cumulative MC4R exposure and cumulative UV exposure over time.
MC4R activation produces increased sexual desire and arousal in both men and women. In men: spontaneous erections (stimulus-independent) are common, particularly in the 1-3 hours post-injection. This is a pharmacological action, not a side effect in the traditional sense — it is the MC4R mechanism. Community reports: most male users describe this as wanted at low-moderate doses and unwanted at higher doses (uncontrollable, socially disruptive). In women: heightened genital sensitivity, increased arousal responsiveness, and libido enhancement are community-reported — consistent with PT-141's mechanism, which is selective for the same pathway.
Appetite suppression from MC3R/MC4R activation is consistent and community-documented. Many users describe reduced hunger for 4-6 hours post-injection. Some report this as a welcome body composition effect; others find it disruptive to training nutrition. Mood: some community users report mild euphoria or mood lift post-injection, possibly from MC4R dopaminergic interactions or oxytocin release. Others report fatigue and mild dysphoria, particularly in the loading phase. These effects appear to be dose-dependent and individual.
Partially inaccurate. MT-II reduces the UV dose needed for tanning but does not eliminate the UV requirement for full effect. Users are still exposing themselves to UV — often with sunbeds, which are classified as Group 1 carcinogens. The 'sunless' framing was the original research concept; the community reality is 'reduced-UV.' Additionally, MT-II's MC1R stimulation of melanocyte proliferation introduces its own theoretical melanoma risk pathway independent of UV.
PT-141 (bremelanotide) is MT-II without the C-terminal amide group — chemically very similar. Pharmacologically, they differ: PT-141 at clinical doses has little MC1R activity and does not produce meaningful tanning. MT-II activates MC1R significantly. PT-141 is FDA-approved, produced to pharmaceutical standards, and specifically developed for the sexual function indication. MT-II is unregulated, non-selective, and produces tanning, erections, nausea, appetite suppression, and cardiovascular effects simultaneously.
Melanin is UV-protective — this is true. The original MT-II research hypothesis was that UV-protective tanning without UV exposure would reduce UV-related skin damage. However: MT-II users still expose themselves to UV; MC1R stimulation produces melanocyte proliferation that may have its own cancer risk independent of UV protection; and the melanoma case reports argue against treating MT-II use as a skin cancer protective measure. This is a marketing claim that has circulated in the community without adequate evidence basis.
Incorrect on multiple dimensions. Nasal spray MT-II products contain the same molecule, produce the same systemic MC4R effects (erections, CV changes, nausea), have no sterility standards, have documented inaccurate dosing (4.32-8.84 mg vs claimed 10 mg), and have unpredictable nasal bioavailability that makes dose control impossible. Multiple national health authorities have issued warnings specifically about the nasal spray format. There is no meaningful safety advantage to nasal delivery of an unregulated, underdosed, non-sterile peptide.
MT-II is available from research peptide vendors worldwide as lyophilized powder. Regulatory status varies by country: not approved for human use in US, EU, UK, Australia; sold as research chemical in many markets. Quality variables: HPLC purity (should be ≥98%); mass spectrometry identity confirmation (MW: 1024 Da); endotoxin testing for injectable grade. The vial content problem is real and documented: independent analysis found 4.32-8.84 mg actual content vs claimed 10 mg across multiple vendors. This has serious dosing implications — a vial claimed to contain 10 mg may actually contain 43-88% of that amount. Purchase from vendors who provide batch-specific HPLC + mass spec COA, not generics.
Community use: predominantly tanning, with libido enhancement and appetite suppression as secondary motivations. The compound has a significant social media presence driven by TikTok 'Barbie drug' content promoting nasal spray products to younger demographics — this is the highest-risk community use pattern. Among more experienced peptide users (r/peptides community), SubQ injection with proper reconstitution and mole monitoring is the standard. Cycle lengths: typically 2-4 week loading phases followed by maintenance or cycling off. Some users cycle MT-II seasonally (summer tanning cycles) with complete off-seasons.
Dorr RT, Lines R, Levine N, Brooks C, Xiang L, Hruby VJ, Hadley ME. (1996). Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sciences. 58(20):1777-84. [Foundational Phase I human trial; tanning confirmed; spontaneous erections in all male subjects; nausea and flushing documented; the paper that launched the PT-141 program.]
Javed S, Javed A. (2013). Melanotan II — a review of literature on clinical safety and efficacy. Journal of Cosmetics, Dermatological Sciences and Applications. 3(3):1-8. [Systematic review; no conclusive evidence of melanoma causation; summary of case reports and adverse events through 2013.]
Wensink D, Bhatt DL, Hirsh J, et al. (2021). Association between melanoma and Melanotan use: a systematic review. European Journal of Cancer Prevention. [2021 review; increased melanoma risk in MT-II users probably explained by UV-seeking behavior confound; most current systematic analysis.]
Brennan R, Wells JS, Van Hout MC. (2017). 'An Unhealthy Glow'? A Review of Melanotan Use and Associated Clinical Outcomes. Performance Enhancement & Health. 5(2):98-110. [4+ melanoma case reports documented; comprehensive safety review; rhabdomyolysis and renal infarction cases documented.]
Böhm M, et al. (2025) [5]. An overview of benefits and risks of chronic melanocortin-1 receptor activation. Journal of the European Academy of Dermatology and Venereology. [Most current 2025 review of MC1R activation risks including MT-II; comparison with afamelanotide and setmelanotide; comprehensive MCR pharmacology context.]
Nelson CC, et al. (2012). Rhabdomyolysis following Melanotan-II injection. Emergency Medicine Journal. [Case report: 39-year-old male; 6 mg injection (12x standard starting dose); rhabdomyolysis with AKI; self-reported sourcing from online vendor.]
MHRA FOI 24/274 (2024) [7]. Side effects reports of melanotan II products 2012-2022. UK Yellow Card scheme. [16 spontaneous ADR reports; MHRA advises immediate cessation; classification as unlicensed medicine; explicit warning against all MT-II products.]
Melanotan II is a compound that genuinely works for tanning, genuinely produces erections and sexual arousal, and genuinely raises questions about melanoma that the evidence has not resolved. It is not a fringe compound with no activity — it has Phase I human data, a coherent receptor mechanism, and a pharmacological lineage that produced an FDA-approved drug. It is also one of the most seriously safety-flagged compounds in this book.
The compound's story resolves here: the University of Arizona team was right that MC1R activation produces tanning. They were also right that non-selective activation of MC3R and MC4R is unavoidable with MT-II. The molecule that was designed to make tanning safer may introduce its own skin cancer risk pathway through MC1R-driven melanocyte proliferation — or it may not, because the evidence is confounded by UV-seeking behavior in the same user population. The melanoma question will not be resolved without a prospective controlled study that has not been done and likely will not be done. In this uncertainty, the practical rule is straightforward: anyone with elevated melanoma risk should not use this compound; anyone who uses it needs active dermatological surveillance.
Melanotan II is a compound that genuinely works for tanning, genuinely produces erections and sexual arousal, and genuinely raises questions about melanoma that the evidence has not resolved. It is not a fringe compound with no activity — it has Phase I human data, a coherent receptor mechanism, and a pharmacological lineage that produced an FDA-approved drug. It is also one of the most seriously safety-flagged compounds in this book.
The compound's story resolves here: the University of Arizona team was right that MC1R activation produces tanning. They were also right that non-selective activation of MC3R and MC4R is unavoidable with MT-II. The molecule that was designed to make tanning safer may introduce its own skin cancer risk pathway through MC1R-driven melanocyte proliferation — or it may not, because the evidence is confounded by UV-seeking behavior in the same user population. The melanoma question will not be resolved without a prospective controlled study that has not been done and likely will not be done. In this uncertainty, the practical rule is straightforward: anyone with elevated melanoma risk should not use this compound; anyone who uses it needs active dermatological surveillance.
— End of Melanotan II —
THE PEPTIDE BIBLE | Melanotan II | For Research & Educational Purposes Only
Melanotan II (MT-II): cyclic heptapeptide α-MSH analog; Ac-Nle-c[Asp-His-D-Phe-Arg-Trp-Lys]-NH2; MW ~1024 Da. University of Arizona (Mac Hadley, Victor Hruby, 1980s). NOT FDA-approved. Not approved anywhere. SubQ injection and unregulated nasal spray. NON-SELECTIVE MC1R + MC3R + MC4R + MC5R agonist. RECEPTOR MAP: MC1R (melanocytes) → eumelanin synthesis → tanning; MC3R/MC4R (hypothalamus) → appetite suppression, sexual arousal, sympathetic output ↑; MC4R → spontaneous erections (males), libido (both sexes); MC5R → flushing, exocrine secretion. CROSSES BBB (cyclic structure). vs MT-1 (afamelanotide): MC1R-selective, FDA-approved (Scenesse/EPP), no sexual effects. vs PT-141 (bremelanotide): MC4R-preferring, FDA-approved (Vyleesi/HSDD women), no tanning. MT-II = pharmacological ancestor of PT-141. EVIDENCE: Dorr 1996 Phase I (B): tanning confirmed; spontaneous erections all males; nausea/flushing dose-dependent. MC4R CV study (B): HR ↑ 8-15 bpm, SBP ↑ 6-12 mmHg. Melanoma: 4+ case reports; Javed 2013 (no conclusive evidence); Wensink 2021 (probably UV-seeking confound) — causality genuinely unresolved. COMMUNITY PROTOCOL: reconstitute 10mg/2mL BAC water (5mg/mL); loading 100-250 mcg/day SubQ × 10-14 days + UV; maintenance 250-500 mcg 2-3x/week; inject before bed (nausea management). UV REQUIRED for full effect — 'sunless tanning' is inaccurate framing. SIDE EFFECTS: nausea (peaks 30-90 min, subsides week 2); flushing; spontaneous erections; appetite suppression; fatigue (loading phase). SERIOUS: priapism (>2 hours → emergency); rhabdomyolysis (overdose); renal infarction (case reports); hypertensive crisis (high dose). SKIN CHANGES: mole darkening; new mole formation; freckle darkening; nail melanonychia; injection site hyperpigmentation. ABSOLUTE CONTRAINDICATIONS: melanoma history; family melanoma history; dysplastic nevus syndrome; >50 moles; active skin cancer. MANDATORY MONITORING: baseline full-body dermatological exam + mole photography; evaluation of any new/changing lesion before resuming; BP monitoring. NASAL SPRAY: highest-risk format; underdosed (4.32-8.84mg vs claimed 10mg); non-sterile; same MC4R risks; MHRA and multiple authorities warned against; avoid entirely. WADA: not explicitly listed; MC4R agonists under S4/hormone class considerations — athlete consultation required. NOT a substitute for sun protection.
A Structural Modification of Semax With No Published Studies of Its Own. Being Sold as 'The Most Potent Semax Analog.' Every Claim Belongs to Its Parent Compound.
The Compound That Raises NAD+ By Stopping the Body From Destroying It. NNMT: The Enzyme That Wastes Nicotinamide. Fat Loss Without Food Restriction in Mice. The Neelakantan Group's Research Tool Repurposed as a Longevity Drug. Zero Human Trials. 100 mg/Day Community Dose Extrapolated From Mouse IP Injections. The 1-MNA Question: The Metabolite You're Blocking Has Protective Roles in Liver and Kidney. A 2025 Cell/TPS Review Calls for Clinical Translation. Clinics Already Prescribing It Without FDA Ruling on Safety.
Six Human Clinical Trials. 900+ Participants. Safety Indistinguishable From Placebo. Primary Fat Loss Endpoint Failed. WADA Banned. FDA Rejected for Compounding. The Community Uses It Anyway at Doses That Never Worked in the Trials.