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Melanotan II (MT-II) is a synthetic cyclic heptapeptide and a superpotent analog of alpha-melanocyte stimulating hormone (alpha-MSH), an endogenous messenger belonging to the melanocortin family. The natural alpha-MSH sequence was truncated and chemically stabilized with a ring-forming lactam bridge. This cyclization protects the molecule from enzymatic degradation and gives it markedly higher potency and a longer duration of action than the unstable native hormone. Melanotan II was originally developed at the University of Arizona in the 1980s, with the goal of researching a "sunless tanning" agent capable of inducing skin pigmentation without prior UV exposure.
Unlike Melanotan I, which acts more selectively at the melanocortin-1 receptor (MC1R), Melanotan II is a non-selective pan-agonist and binds to multiple melanocortin receptor subtypes, including MC1R, MC3R, MC4R, and MC5R. This broader receptor activation produces the two effect groups most frequently described in research: pronounced stimulation of melanin production (pigmentation) via MC1R, and an influence on central nervous pathways linked to appetite regulation and sexual arousal via MC3R and MC4R. This dual profile fundamentally distinguishes Melanotan II from simpler "tanning peptides."
Melanotan II is not an approved drug. It is traded strictly as a research-use compound. The observations summarized here come predominantly from preclinical work and from early, small Phase I studies (such as Dorr and colleagues, Life Sciences 1996, and Wessells and colleagues, Urology 2000). Robust long-term human data is largely absent, so every consideration remains within a research framing.
Melanotan II exerts its effects exclusively through activation of melanocortin receptors, a family of G-protein-coupled receptors. Each subtype mediates a distinct biological signal:
In research practice, Melanotan II is not used at a full dose immediately but is introduced gradually through a loading phase. Because of its pronounced effects on pigmentation and appetite, it is customary to begin at the low end of the range and increase the dose stepwise until a stable maintenance state is reached.
A common vial size is 10 mg. Adding 2 mL of bacteriostatic water gives a concentration of 5 mg/mL (5,000 mcg/mL).
At a maintenance dose of 0.25 mg, a 10 mg vial provides 40 administrations. The very small volumes at low doses can be hard to read accurately, so it can be useful to use more BAC water to lower the concentration and enlarge the readable volume. Use the Melanotan II calculator above to compute exact volumes and units for any vial size, reconstitution volume, and target dose.
Melanotan II is supplied as a lyophilized (freeze-dried) powder in sealed vials and must be reconstituted with bacteriostatic water (BAC water) before use. BAC water contains 0.9% benzyl alcohol, which inhibits microbial growth and extends the usable window of the dissolved solution. Sterile water for injection is less suitable for multi-dose vials.
If the solution appears cloudy, discolored, or contains visible particulate matter, discard the vial and do not use it.
Compared with purely regenerative peptides, Melanotan II has a considerably more pronounced side effect profile because, as a pan-agonist, it engages several receptor systems at once. Many of the reported effects are direct consequences of the mechanism of action rather than signs of contamination or toxicity. Robust long-term human data is absent.
Consultation with a qualified healthcare professional is strongly recommended, particularly because of the dermatological safety considerations.
Melanotan II is frequently compared in research with Melanotan I. Melanotan I (afamelanotide) is more selective for the MC1R and therefore produces very few central nervous effects such as nausea, appetite suppression, or spontaneous erections. It is regarded in research as the more tolerable but slower-acting melanocortin peptide. A genuine simultaneous combination of the two is uncommon because their pigmentation pathways overlap; what matters more is the deliberate choice between potency (MT-II) and selectivity (MT-I).
PT-141 (bremelanotide) is a direct derivative of Melanotan II in which the amino group has been removed. As a result, PT-141 focuses on the central MC3R/MC4R effects related to sexual arousal without producing meaningful pigmentation. Combining the two peptides is unusual in research, as they engage overlapping receptors and their inflammatory and circulatory effects could add up. The comparison is more conceptual in nature and illustrates how a non-specific pan-agonist was refined into a targeted analog.
Because of its pan-agonist properties and broad range of effects, Melanotan II is almost always considered as a single compound rather than within stacks in research practice. Combining it with additional centrally or vascularly active peptides increases complexity and makes it harder to attribute effects. Research-grade Melanotan II is available directly from BergdorfBio: Melanotan II at BergdorfBio.
Melanotan I is more selective for the melanocortin-1 receptor and therefore produces mostly pigmentation with only minor central nervous effects. Melanotan II is a pan-agonist that additionally activates MC3R and MC4R, so it acts more strongly, more quickly, and with more pronounced side effects such as nausea, appetite suppression, and sexual arousal. Melanotan I is regarded as more tolerable, Melanotan II as more potent.
The IU scale on an insulin syringe is purely a volume scale: 1 IU equals 0.01 mL. The mass contained in that volume depends entirely on the concentration of the dissolved solution. At 5 mg/mL, 5 IU contains exactly 0.25 mg of peptide. The calculator translates your target dose in milligrams into the corresponding volume and the units to read off.
Melanotan II stimulates melanocytes directly and can therefore, in principle, deepen pigmentation independently of UV. Research literature nonetheless describes that moderate UV exposure accelerates visible tanning because it triggers additional melanocyte activity. Excessive UV exposure is not advisable.
In the loading phase, low doses, often daily, are used to reach a visible pigmentation level. Once that level is reached, research practice transitions to a maintenance phase, in which dosing occurs only 2–3 times per week to hold the state. The slow loading phase also reduces nausea and circulatory effects.
The nausea is a direct consequence of activating central melanocortin receptors, particularly the MC4R, and is not a sign of contamination. It is most common at the start and after dose increases and usually subsides as use continues. A low starting dose and a slow ramp are the most important measures.
No. Melanotan II is not approved as a drug. It is traded strictly as a research-use compound. Various health authorities have warned against uncontrolled use, particularly because of the dermatological safety considerations and the risks posed by untested material.
Because Melanotan II directly increases melanin production, existing moles, freckles, and pigment spots may appear darker, and new pigment spots may become visible. This is the most frequently cited safety-relevant observation. Regular dermatological monitoring is considered important in the research context.
BergdorfBio offers research-grade Melanotan II with verified purity and concentration. View the product page: Buy Melanotan II at BergdorfBio. All products are sold strictly for research purposes.
Medical Disclaimer: The information on this page is provided for educational and research purposes only. Melanotan II is not an approved drug or medical treatment and is sold strictly for research use. Nothing on this page constitutes medical advice, diagnosis, or a recommendation to use any specific compound. Always consult a qualified healthcare professional before beginning any peptide protocol. BergdorfBio assumes no liability for the use or misuse of the information presented here.
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Melanotan II