# Melanotan II: Research Overview — Peptide Rejuvination > A literature summary of Melanotan II, a non-selective melanocortin receptor agonist studied for pigmentation, appetite, and sexual function. Covers mechanism, controlled-trial findings, community-reported effects, and documented safety cautions. A synthetic melanocortin agonist that darkens skin without sun exposure — with a small controlled-trial base from the 1990s and a growing, more recent case-report record of pigmentation and vascular harms. ## The short version Melanotan II is a lab-made peptide that copies and amplifies a natural human hormone, alpha-melanocyte-stimulating hormone (alpha-MSH). It switches on melanocortin receptors — the same family of switches that sunlight normally triggers — so skin darkens without UV exposure. It also acts on melanocortin receptors in the brain, which is why it affects appetite and sexual arousal as well as skin color. Melanotan II has **never been approved** by the FDA or any other regulator, for tanning or anything else. Its human evidence base is a handful of small controlled trials from the late 1990s and early 2020s, none of which reached late-stage development [9][12]. Set against that thin controlled base is a growing modern record of case reports describing pigmentation changes, kidney injury, and other adverse events in people using unregulated product [8][10]. This page describes what was studied and what has been documented — never a dose or a use to pursue. ## What it is Melanotan II is a cyclic (lactam-bridged) seven-amino-acid analog of alpha-MSH: Ac-Nle4-cyclo[Asp5-His6-D-Phe7-Arg8-Trp9-Lys10]-NH2, a truncated and chemically stabilized version of the natural hormone's active core, molecular formula C50H69N15O9. It was designed at the University of Arizona in the late 1980s to resist enzymatic breakdown and to activate melanocortin receptors far more potently than the natural hormone. Unlike GHK-Cu, BPC-157 or TB-500, Melanotan II is not a fragment of a peptide already circulating in the body in that form — it is an engineered analog, built specifically to be a stronger and longer-lasting melanocortin signal than alpha-MSH itself. That engineered potency is central to both its pigmentation effect and its broader, less selective activity across the melanocortin receptor family — MC1R, MC3R, MC4R, and MC5R — which is why its effects extend well beyond skin color. ## How it works Melanotan II is a **non-selective agonist across the melanocortin receptor family (MC1R-MC5R)**. Activating MC1R on melanocytes raises intracellular cAMP and drives the PKA-CREB-MITF signaling cascade, which upregulates the enzyme tyrosinase and shifts pigment production toward eumelanin (the darker pigment type) — producing skin and hair darkening independent of sun exposure. Because the same receptor family operates in the brain, Melanotan II's effects are not confined to skin. Central MC4R (and MC3R) activation in the hypothalamus and the brain's reward circuitry (mesolimbic system) suppresses food intake and promotes sexual arousal — effects documented in both animal and early human studies [9][12]. In male mice, bilateral microinjection of Melanotan II directly into the nucleus accumbens (a reward-circuit structure) significantly reduced food consumption and food-seeking behavior in both free-feeding and effortful-access paradigms, without producing a learned food aversion or altering metabolic rate — evidence that the appetite effect is a specific reward-circuit action, not general illness [9]. ## What the research shows *Pigmentation — a 2026 case report.* A man who self-administered Melanotan II at 400 micrograms subcutaneously every other day for 64 days (12.8 mg cumulative) developed brown pigmentation on the gum tissue (attached gingiva) of both jaws and on the inside of his cheeks (buccal mucosa). The cheek pigmentation began fading within 28 days of stopping, but the gum pigmentation was still present, at reduced intensity, three months later [8]. *Appetite — mouse model.* In male C57BL/6J mice, microinjecting Melanotan II directly into the nucleus accumbens (0.1-1 nanomoles per side) significantly decreased both home-cage food consumption and effortful responding for food access, with no conditioned taste aversion and no change in metabolic rate — indicating a targeted reward-circuit appetite effect rather than general sickness behavior [9]. *Kidney injury — case report and literature review.* A nephrology case report describes renal infarction most likely attributable to Melanotan II use, with the authors noting that Melanotan II-induced rhabdomyolysis (muscle breakdown) and renal failure had been described previously in the literature, and that both a thrombotic (clot-related) effect and a possible direct toxic effect on kidney tissue must be considered as mechanisms [10]. *Historical and regulatory context.* A review of melanocortin peptide therapeutics documents that the linear analog Melanotan I and the cyclic, truncated Melanotan II were both patented and tested clinically — Melanotan I for skin tanning, Melanotan II for male erectile dysfunction — and that a further Melanotan-II-derived analog advanced toward pivotal trials and eventual approval for sexual dysfunction in both sexes [11]. *Erectile function — controlled human trial.* In a double-blind, placebo-controlled crossover study of 10 men with psychogenic erectile dysfunction, a subcutaneous Melanotan II dose of 0.025 mg/kg produced clinically apparent erections in 8 of the 10 men; the mean duration of over 80% tip rigidity was 38.0 minutes with Melanotan II versus 3.0 minutes with placebo (p=0.0045), with transient nausea, stretching and yawning that required no treatment [12]. ## Reported effects, cautions & safety Online community accounts of Melanotan II use converge on a familiar and, in places, concerning pattern — **anecdotal, not clinical evidence**, since none of it comes from a controlled trial and none specifies a verified dose or product purity. *Reported benefits (anecdotal, not clinical findings):* A rapid, deep tan with little sun exposure is the most consistently cited reason people use it, alongside reduced appetite (sometimes from the first dose), increased libido and, in men, spontaneous erections. A subset describe general cosmetic satisfaction and confidence with the resulting tan. *Reported adverse effects (anecdotal, not clinical findings):* Nausea, often within the first hour of a dose, is described almost universally, alongside facial flushing, an urge to stretch and yawn, and fatigue or lethargy in the early days ('melanotan flu'). More concerning cosmetic reports recur across accounts: an uneven, blotchy or unnaturally long-lasting tan; darkening of existing moles and freckles, often noticed before the tan itself; and, in a recurring and worrying subset of long-term users, the appearance of entirely new moles — frequently cited as the reason people eventually see a doctor. Darkening of lips, scars, and genital skin, and injection-site redness or swelling, are also described. *Cited cautions from the clinical and case-report literature:* - **New or changing moles, and melanoma risk:** because Melanotan II activates melanocytes throughout the skin non-selectively, published case reports describe new and changing moles, and — in a smaller number of reports — melanoma diagnosed in people using it. Any new or changing mole during or after use warrants prompt dermatological evaluation. - **Kidney and muscle injury:** a documented case links Melanotan II use to renal infarction, with the case authors noting that rhabdomyolysis and renal failure had been described previously in melanotan users, and that both clot-related and direct toxic mechanisms are plausible [10]. - **Priapism and cardiovascular effects:** because melanocortin agonism promotes erections, case reports describe priapism (a painful, prolonged erection requiring emergency treatment) following melanotan use, and the receptor family's broader activity raises documented concerns about blood pressure and vascular tone. - **No regulatory approval and unregulated supply:** Melanotan II has never been approved by the FDA or any other regulator for any indication [11], and product sold outside a clinical-trial setting cannot be verified for identity, purity, or sterility — a fact regulators in several countries have specifically warned about. - **Not a substitute for the separately approved, distinct melanocortin compounds** that were later developed from this same peptide family for a rare skin condition and for sexual desire disorder — those approvals and their safety data do not extend to Melanotan II itself [11]. ## Where it fits in Skin & Aesthetics research Melanotan II is the pigmentation anchor on this desk — a single, well-characterized receptor mechanism (MC1R-driven melanogenesis) with real, if dated and incomplete, controlled human data, set against a case-report record that has grown considerably since those early trials. Where [GLOW](/glow) works on skin's structure through three separate, additive mechanisms, Melanotan II works on skin's color through one broadly acting one — and that same broad activity is what produces its documented off-target effects on appetite, sexual function, and, in case reports, the kidney. See the [comparison page](/compare) for the side-by-side. ![Melanotan II research illustration — abstract melanocortin pathway motifs in deep pine and teal](/images/melanotan-2.webp) --- A clinician's-briefing digest of skin-remodeling and pigmentation research peptides — no products, no prescriptions, just the literature.