Also known as: MT-2, MT-II, Melanotan 2
Half-life: ~33 minutes
Melanotan II is a synthetic cyclic heptapeptide analog of alpha-melanocyte stimulating hormone (alpha-MSH) that was originally developed at the University of Arizona as a sunless tanning agent to reduce skin cancer risk. By binding to melanocortin-1 receptors (MC1R) on melanocytes, it stimulates melanin production and skin darkening without requiring UV exposure. However, Melanotan II is a non-selective melanocortin agonist, also activating MC3R and MC4R, which mediate effects on appetite suppression, fat metabolism, and sexual arousal.
The discovery of its sexual arousal side effects during early clinical trials led directly to the development of PT-141 (bremelanotide), a derivative compound designed specifically for sexual dysfunction. PT-141 was eventually approved by the FDA as Vyleesi for hypoactive sexual desire disorder. Melanotan II itself was never pursued through regulatory approval due to its broad, non-selective receptor activity and the associated range of off-target effects, including nausea, facial flushing, and spontaneous erections.
Despite lacking regulatory approval in any country, Melanotan II has become one of the most widely used cosmetic peptides globally, particularly in the tanning and bodybuilding communities. Major regulatory agencies including the FDA, TGA (Australia), and MHRA (UK) have issued consumer warnings about its use. The most significant safety concern beyond acute side effects is the potential for stimulating melanocyte proliferation and darkening of existing moles and nevi, which has raised theoretical concerns about melanoma risk in predisposed individuals.
Melanotan II was developed in the early 1990s at the University of Arizona by Dr. Victor Hruby and colleagues in the Department of Chemistry. The research was part of an effort to develop a safe tanning agent that could protect fair-skinned individuals from UV radiation and reduce skin cancer risk. Clinical trials at the University of Arizona in 1996 demonstrated its tanning efficacy in humans. However, the unexpected sexual arousal side effects led to the development of a derivative compound, PT-141 (bremelanotide), specifically targeting sexual dysfunction. Palatin Technologies pursued PT-141 through clinical development, eventually leading to FDA approval as Vyleesi. Melanotan II itself was never pursued through the regulatory approval process due to its broad, non-selective receptor activity. Despite this, it became one of the most widely used peptides in the cosmetic and bodybuilding communities, often obtained through online peptide suppliers.
Melanotan II has a moderate tolerability profile with significant initial side effects that typically diminish with continued use. Nausea is the most common side effect, occurring in the majority of first-time users, and can be mitigated by starting with low doses (250 mcg) and titrating up gradually. Facial flushing is common but transient. The most significant safety concern is the darkening of existing moles and the theoretical risk of promoting melanocyte proliferation, which has led dermatologists to caution against use in individuals with a history of melanoma or atypical moles. Spontaneous erections in men can be socially inconvenient. Long-term safety data from controlled studies is not available.
Dose Range
250-500 mcg
Frequency
Once daily
Duration
2-3 weeks
Dose Range
250-500 mcg
Frequency
Once or twice weekly
Duration
Ongoing with UV exposure
Dose Range
500-1000 mcg
Frequency
As needed, 1-2 hours before activity
Duration
As needed
Dosing information is for educational purposes only. Consult a healthcare professional before using any peptide.
Typical Vial Size
10 mg
Water Type
Bacteriostatic water (BAC water)
Mixing Volume
2 mL
Half-Life
~33 minutes
Molecular Weight
1024.2 Da
Store reconstituted vial refrigerated at 2-8°C. Use within 28 days. Start with low dose (250 mcg) to assess tolerance due to common nausea. Protect from light.
FDA Status
Not FDA approved. The FDA has issued warnings against the use of Melanotan II, citing it as an unregulated and potentially dangerous product. The derivative PT-141 (bremelanotide/Vyleesi) was approved for sexual dysfunction but Melanotan II itself was not pursued for approval.
Legal Status
Unregulated in most countries. Banned or restricted in some jurisdictions. The TGA (Australia) and MHRA (UK) have issued warnings. Classified as a research chemical. Not approved for human use in any country.
USA
Not approvedFDA has issued consumer warnings. Classified as unapproved drug.
EU
Not approvedEMA has not authorized. Multiple EU agencies have issued warnings.
UK
Not approvedMHRA has issued safety warnings against use.
Australia
Not approvedTGA has banned importation for personal use and issued multiple warnings.
Canada
Not approvedHealth Canada has not authorized.
Dorr RT, Dvorakova K, Brooks C, Lines R, Levine N, Schram K, Miketova P, Hruby VJ, Alberts DS
Annals of the New York Academy of Sciences (1999)
Clinical demonstration that subcutaneous Melanotan II effectively stimulates melanogenesis and tanning in human subjects, with dose-dependent increases in skin pigmentation.
View Study →Wessells H, Fuciarelli K, Hansen J, Hadley ME, Hruby VJ, Dorr R, Levine N
Journal of Urology (1998)
Demonstrated that Melanotan II produces erections in men with erectile dysfunction, establishing the melanocortin receptor pathway as a target for sexual dysfunction treatment.
View Study →Habbema L, Halk AB, Neumann M, Bergman W
British Journal of Dermatology (2017)
Reviewed the dermatological risks of Melanotan II use, including changes in nevi and the theoretical concern of melanocyte proliferation and melanoma risk.
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