Melanotan II

Overview

Melanotan II (MT-II) is a cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (α-MSH) — Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 — developed at the University of Arizona in the 1980s by Hruby, Hadley, and colleagues as a candidate photoprotection / sunless-tanning agent. It has never been approved by the FDA or any other regulator for any indication; clinical development was abandoned and it is sold only via grey-market research-chemical channels. Genuine safety signals have been reported, including darkening of existing moles, eruptive atypical nevi, and case reports of new primary melanoma in young tanning-seeking users.

Mechanism of Action

MT-II is a non-selective agonist at all four peripheral melanocortin receptors — MC1R (melanocyte pigmentation), MC3R and MC4R (energy balance and central sexual arousal), and MC5R (exocrine gland function). MC1R activation on melanocytes increases cAMP → PKA → MITF → tyrosinase, driving eumelanin synthesis; UV exposure is generally required to produce visible tanning. MC4R activation in the hypothalamus mediates the prominent sexual arousal and spontaneous erection side effects seen in the original Phase I trials — this observation was the basis for developing the selective C-terminal analog bremelanotide (PT-141, Vyleesi) for female HSDD.

Research Summary

Melanotan II was developed by Hruby, Hadley, and colleagues at the University of Arizona in the 1980s. The seminal Phase I clinical study is Dorr et al. (Life Sciences, 1996; PMID 8637402), a pilot trial in three healthy male volunteers that documented dose-dependent pigmentation together with nausea, a 'stretching and yawning complex,' and spontaneous penile erections — the MC4R sexual-arousal signal that later motivated the development of bremelanotide (PT-141/Vyleesi). MT-II itself was never advanced to Phase III and has never received regulatory approval in any jurisdiction. As unregulated consumer use expanded through the 2000s, dermatology literature accumulated safety signals: Langan et al. (BMJ 2009, PMID 19174439) reported changes in moles among young users of unlicensed 'sun tan jab' preparations; Cardones & Grichnik (Arch Dermatol 2009, PMID 19380666) described alpha-MSH-induced eruptive atypical nevi in a patient with dysplastic nevi and prior melanoma who used MT-II; Evans-Brown et al. (BMJ 2009, PMID 19224885) documented widespread unregulated population use. Further case reports describe new primary cutaneous melanoma in young MT-II users and rare rhabdomyolysis. Regulators (FDA, UK MHRA, Australian TGA) have explicitly warned against use. Note: the Barnetson et al. 2006 photoprotection study (J Invest Dermatol, PMID 16763547) evaluated the related linear analog [Nle4-D-Phe7]-alpha-MSH (afamelanotide / Melanotan-I), not MT-II. Category 2 classification reflects documented safety concerns from non-selective melanocortin activation combined with oncologic signals.

Vendors selling Melanotan II

Scored vendors carrying Melanotan II, ranked by trust grade. Grades are computed from indexed Certificates of Analysis. Full $/mg pricing is on the comparison page.

Prescribers who offer Melanotan II

37 prescribers in our directory work with Melanotan II, each confirmed from their own website. Peptides like Melanotan II require a prescription from a licensed provider — telehealth options are available.

Reported Side Effects

• Nausea (very common, especially during loading)
• Facial flushing and transient hypertension
• Spontaneous penile erections / yawning-stretching complex (MC4R-mediated)
• Darkening of existing moles and freckles
• Eruption of new atypical nevi (case reports)
• New primary cutaneous melanoma (case reports in young tanning-seeking users)
• Rhabdomyolysis (rare case reports)
• Appetite suppression
• Fatigue, dizziness, headache
• Injection-site reactions

Compare Melanotan II with Others

Research References

• Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study (Dorr et al., Life Sci) (1996)
• Change in moles linked to use of unlicensed 'sun tan jab' (Langan et al., BMJ) (2009)
• alpha-Melanocyte-stimulating hormone-induced eruptive nevi (Cardones & Grichnik, Arch Dermatol) (2009)
• Use of melanotan I and II in the general population (Evans-Brown et al., BMJ) (2009)

Frequently asked questions

Has Melanotan II been independently lab-tested?

Disclosed Labs has collected 65 Certificates of Analysis (COA) for Melanotan II from 12 independent testing labs. 37 vendors have submitted material for testing. Products average 99.7% tested purity across the corpus. Full testing data is available at https://www.disclosedlabs.com/peptides/melanotan-ii/testing.

What is the average purity of Melanotan II on the market?

Based on 65 COAs analyzed by Disclosed Labs, Melanotan II products average 99.7% (±0.3%) tested purity. Individual vendor results vary; see per-vendor COA data at https://www.disclosedlabs.com/peptides/melanotan-ii/coas.

Which labs have tested Melanotan II?

Independent labs that have tested Melanotan II include: ILS Labs (Grade A), Ethos Analytics (Grade B). Full lab credibility grades and profiles are at https://www.disclosedlabs.com/labs.

Where can researchers source Melanotan II?

8 vendors with Disclosed Labs trust grades currently list Melanotan II, including Instant Peptides, Glacier Aminos, Ion Peptide. Compare live prices and lab-verified COAs at https://www.disclosedlabs.com/prices/melanotan-ii.

Which prescribers offer Melanotan II with a prescription?

37 prescribers in the Disclosed Labs directory work with Melanotan II, each confirmed from their own website, with telehealth options available. Melanotan II requires a prescription from a licensed provider. Browse them at https://www.disclosedlabs.com/prescribers?peptide=Melanotan%20II.

How does Melanotan II work?

MT-II is a non-selective agonist at all four peripheral melanocortin receptors — MC1R (melanocyte pigmentation), MC3R and MC4R (energy balance and central sexual arousal), and MC5R (exocrine gland function). MC1R activation on melanocytes increases cAMP → PKA → MITF → tyrosinase, driving eumelanin synthesis; UV exposure is generally required to produce visible tanning. MC4R activation in the hypothalamus mediates the prominent sexual arousal and spontaneous erection side effects seen in the original Phase I trials — this observation was the basis for developing the selective C-terminal analog bremelanotide (PT-141, Vyleesi) for female HSDD.

What does the research say about Melanotan II?

Melanotan II was developed by Hruby, Hadley, and colleagues at the University of Arizona in the 1980s. The seminal Phase I clinical study is Dorr et al. (Life Sciences, 1996; PMID 8637402), a pilot trial in three healthy male volunteers that documented dose-dependent pigmentation together with nausea, a 'stretching and yawning complex,' and spontaneous penile erections — the MC4R sexual-arousal signal that later motivated the development of bremelanotide (PT-141/Vyleesi). MT-II itself was never advanced to Phase III and has never received regulatory approval in any jurisdiction. As unregulated consumer use expanded through the 2000s, dermatology literature accumulated safety signals: Langan et al. (BMJ 2009, PMID 19174439) reported changes in moles among young users of unlicensed 'sun tan jab' preparations; Cardones & Grichnik (Arch Dermatol 2009, PMID 19380666) described alpha-MSH-induced eruptive atypical nevi in a patient with dysplastic nevi and prior melanoma who used MT-II; Evans-Brown et al. (BMJ 2009, PMID 19224885) documented widespread unregulated population use. Further case reports describe new primary cutaneous melanoma in young MT-II users and rare rhabdomyolysis. Regulators (FDA, UK MHRA, Australian TGA) have explicitly warned against use. Note: the Barnetson et al. 2006 photoprotection study (J Invest Dermatol, PMID 16763547) evaluated the related linear analog [Nle4-D-Phe7]-alpha-MSH (afamelanotide / Melanotan-I), not MT-II. Category 2 classification reflects documented safety concerns from non-selective melanocortin activation combined with oncologic signals.