Skin pigmentation, melanocortin signaling, sexual function, appetite regulation
Melanotan II (MT-2)
A synthetic melanocortin receptor agonist studied for skin pigmentation, sexual function, appetite signaling, and other physiological effects mediated through the melanocortin system.
Administration Reference
Subcutaneous
Source / Evidence Context
Mixed sources
Dose Information
100mcg for 5 days then 500 mcg per injection
Frequency
Daily during initial pigmentation protocols
Duration / Cycle
daily use commonly continues until desired pigmentation develops
Off-Cycle
Not established
Timing
Nightly or 1/2 hour before uv exposure
Storage Guidance
Refrigerate after reconstitution and use within approximately 30 days, Freeze for lyophilized powder form
Supplies
Affiliate disclosure: We may earn a commission if you purchase through these links.
Listings are not a required kit or confirmation of suitability for a particular peptide, formulation, or route. Check the product specifications and intended use.
Syringes & transfer supplies
EasyTouch U-100 Insulin Syringes (31G 0.5cc 5/16″) – 100ct.U-100 Insulin Syringes (31G 0.5cc 5/16") – 100ctInsulin syringes – Polybag, 50 Unit Capacity, 5/16” Needle Length, Bold Markings for Accurate Dosing, Disposable, Box of 100View at AMAZON →
Protective supplies & disposal
MED PRIDE Sterile Alcohol Prep Pads1 BOX OF 200INDIVIDUALLY WRAPPED ISOPROPYL ALCOHOL WIPES, PACK OF 1 BOX OF 200, MEDIUM SIZE PREP PADSView at AMAZON →
Inspire Black Nitrile Gloves HEAVY DUTY 6 Mil100ctView at AMAZON →
Square Sharps Container, 2 QuartQTY 1View at AMAZON →
Commonly Reported Uses
Skin pigmentation and tanning; sexual-arousal and erectile-function research; appetite suppression; melanocortin-receptor research. Melanotan II is not an approved treatment for any of these uses.
Commonly Reported Indicators
Progressive skin darkening, darkening of existing freckles or nevi, reduced appetite, nausea or flushing, increased sexual desire, and spontaneous erections have been reported in human studies and case literature.
Mechanism Overview
Melanotan II is a nonselective melanocortin agonist with activity at MC1R, MC3R, MC4R, and MC5R. MC1R activation promotes melanogenesis, while central melanocortin signaling—particularly MC3R and MC4R—affects appetite, sexual behavior, and energy regulation.
Safety
Safety Considerations
Human studies were small and short-term, while post-market use has generated case reports involving priapism, systemic sympathomimetic toxicity, rhabdomyolysis, renal dysfunction or infarction, rapidly changing nevi, and melanoma. FDA also identifies potential immunogenicity and peptide-impurity concerns with compounded Melanotan II.
Reported Adverse Effects
Nausea, flushing, yawning, stretching, fatigue, somnolence, reduced appetite, spontaneous erections, increased sexual desire, and pigmentation changes. Serious case reports include priapism, tachycardia and sympathomimetic toxicity, rhabdomyolysis, renal injury, and melanocytic changes.
Contraindications & Cautions
Particular caution is warranted with a history of melanoma, dysplastic or atypical nevi, unexplained changing pigmented lesions, cardiovascular disease, uncontrolled hypertension, kidney disease, pregnancy or breastfeeding, and conditions in which prolonged erections would present added risk.
Cancer Considerations
Editorial evidence assessment, not a validated risk score or clearance for use. Unknown risk does not mean low risk; these notes do not establish safety during active cancer or remission.
Cancer Concern Assessment
Elevated concern
Basis for Concern
Melanotan II directly stimulates melanocortin signaling involved in melanocyte activity and pigmentation. Multiple reports describe rapid darkening or emergence of atypical nevi, and several melanomas have been reported during or after use. These observations do not establish causation, but they create a stronger cancer-related concern than exists for many research peptides.
Active Cancer
Significant concern
The concern is strongest for active melanoma or other melanocytic malignancy because Melanotan II directly stimulates melanocortin pathways in pigment-producing cells. Human data are insufficient to quantify tumor-progression risk, and evidence for non-melanocytic cancers is substantially less direct.
Prior Cancer / Remission
Elevated caution
A prior history of melanoma or dysplastic-nevus syndrome warrants particular caution because published reports describe melanocytic changes and melanoma temporally associated with melanotan exposure. No evidence-based remission interval has been established. Evidence regarding prior non-melanocytic cancers is insufficient.
Status
Regulatory Status
Melanotan II is not FDA approved for tanning, sexual function, weight management, or any other therapeutic indication. FDA identifies Melanotan II among bulk substances presenting potential safety concerns and notes published serious adverse-event reports including melanoma, priapism, sympathomimetic toxicity, and posterior reversible encephalopathy syndrome.
Development / Research Status
Human research compound
Market Classification
Research-use compound
Status Notes
Melanotan II underwent small early human studies but did not become an approved drug. It should not be confused with afamelanotide or bremelanotide, separate melanocortin-based drugs with different structures, receptor profiles, and regulatory histories.
Research & Evidence
Evidence Level
Human clinical research
Research Last Reviewed
2026-09-05
Research Overview
Melanotan II has limited direct human evidence from small early-phase pigmentation and erectile-function studies. These studies confirm biological activity in humans but are too small and short-term to establish long-term safety or support contemporary therapeutic use. Subsequent literature is dominated by mechanistic research and adverse-event case reports.
Human Research
A 1996 Phase I study enrolled three healthy men receiving subcutaneous Melanotan II starting at 0.01 mg/kg and escalating to 0.025–0.03 mg/kg. Increased pigmentation occurred, alongside nausea, fatigue, yawning, and spontaneous erections. A subsequent double-blind crossover study in 10 men with psychogenic erectile dysfunction found clinically apparent erections in 8 of 10 participants after 0.025 mg/kg. A later report involving 20 men with psychogenic or organic erectile dysfunction found erections in 17 of 20 participants and increased sexual desire after 68% of Melanotan II doses versus 19% with placebo.
Animal Research
Melanotan II has been extensively used as an experimental melanocortin agonist in animal models. MC4R-related research demonstrates effects on food intake and energy homeostasis, while MC1R activation drives melanogenesis. These studies helped establish the broader physiological roles of melanocortin receptors but do not establish long-term human safety.
In Vitro Research
Receptor-characterization studies identify Melanotan II as a potent cyclic agonist at MC1R, MC3R, MC4R, and MC5R. Activation primarily increases intracellular cAMP through G-protein-coupled melanocortin receptor signaling, providing the mechanistic basis for effects on pigmentation, appetite, and sexual function.
References
Dorr RT, Lines R, Levine N, et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci. 1996;58(20):1777-1784. PMID 8637402. DOI 10.1016/0024-3205(96)00160-9.
Wessells H, Fuciarelli K, Hansen J, et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. J Urol. 1998;160(2):389-393. PMID 9679884.
Wessells H, Levine N, Hadley ME, Dorr R, Hruby V. Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II. Int J Impot Res. 2000;12 Suppl 4:S74-S79. PMID 11035391. DOI 10.1038/sj.ijir.3900582.
Habbema L, Halk AB, Neumann M, Bergman W. Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review. Int J Dermatol. 2017;56(10):975-980. PMID 28266027. DOI 10.1111/ijd.13585.
Cousen P, Colver G, Helbling I. Eruptive melanocytic naevi following melanotan injection. Br J Dermatol. 2009;161(3):707-708. PMID 19575725. DOI 10.1111/j.1365-2133.2009.09362.x.
Paurobally D, Jason F, Dezfoulian B, Nikkels AF. Melanotan-associated melanoma. Br J Dermatol. 2011;164(6):1403-1405. PMID 21564053. DOI 10.1111/j.1365-2133.2011.10273.x.
Reid C, Fitzgerald T, Fabre A, Kirby B. Atypical melanocytic naevi following melanotan injection. Ir Med J. 2013;106(5):148-149. PMID 23914578.
Melanoma associated with the use of melanotan-II. PMID 24355990.
Schulze F, Erdmann H, Hardkop LH, et al. Eruptive naevi and darkening of pre-existing naevi 24 h after a single mono-dose injection of melanotan II. Eur J Dermatol. 2014;24(1):107-109. PMID 24334249. DOI 10.1684/ejd.2013.2227.
Nelson ME, Bryant SM, Aks SE. Melanotan II injection resulting in systemic toxicity and rhabdomyolysis. Clin Toxicol. 2012;50(10):1169-1173. PMID 23121206. DOI 10.3109/15563650.2012.740637.
Peters B, Hadimeri H, Wahlberg R, Afghahi H. Melanotan II: a possible cause of renal infarction: review of the literature and case report. CEN Case Rep. 2020;9(2):159-161. PMID 31953620. DOI 10.1007/s13730-020-00447-z.
Melanotan-induced priapism: a hard-earned tan. PMID 30796078. DOI 10.1136/bcr-2018-227644.
Alsabbagh AY, Bhujel N, Singh RP. Melanotan II nasal spray: a possible risk factor for oral mucosal malignant melanoma? Int J Oral Maxillofac Surg. 2025;54(9):806-808. PMID 40210573. DOI 10.1016/j.ijom.2025.03.014.
Hruby VJ, et al. Bench-Top to Clinical Therapies: A Review of Melanocortin Ligands from 1954 to 2016. Molecules. 2017.
U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks — Melanotan II