library.onepin.app/mt-ii Peptide Education Library

Education only, not medical advice◆ 21+◆ Every dose is an example to finalize with a licensed provider

OnePin Peptide Library · Hormonal

Hormonal Synthetic cyclic peptide Not FDA-approved · investigational

MT-II

MT-2 · MT2 · Melanotan II · Melanotan 2

Synthetic cyclic peptideNon-selective melanocortin receptor agonist (MC1R-MC5R)Alpha-MSH analogMelanogenesis activator

Melanotan II (MT-II) is a synthetic cyclic heptapeptide analog of alpha-melanocyte stimulating hormone (alpha-MSH) that activates melanocortin receptors (MC1R through MC5R) with broad affinity. Its cyclic disulfide bridge structure (between positions 4 and 10) enhances stability and receptor binding compared to linear alpha-MSH. MT-II stimulates melanogenesis (skin darkening via melanocyte activation), suppresses appetite, and enhances sexual arousal through central melanocortin signaling. The tanning effect occurs with or without UV exposure but is significantly enhanced by sun/UV. MT-II is used at very low doses (100-250 mcg) and requires solo administration due to its complex receptor pharmacology.

Quick Start

Route

SubQ injection

Start low

100-250 mcg

Frequency

1-2 times weekly for maintenance

Timing

No fasting required. Can cause nausea; some users prefer to eat beforehand.

Evening dosing before bed. Loading phase first (1-2 weeks daily), then maintenance 2x/week. Nausea common initially - start low.

❋

Start here. Every protocol below is ordered lowest-first. Begin at the smallest effective dose, hold about a week to assess tolerance, and step up only if needed.

Tiered Protocols · lowest first

Quick Start

Conservative start

100-250 mcg · SubQ injection · 1-2 times weekly for maintenance

Lowest starting point. Hold about a week to assess tolerance before stepping up.

100-250 mcg

1-2 times weekly for maintenance

Standard

Tanning Protocol

250-500 mcg · SubQ · Daily

human clinical trial · Dorr et al. 1996 (Life Sci)

250-500 mcg

Daily

Intermediate

Pro-Sexual (Acute)

500-1000 mcg · SubQ · As needed

human clinical trial · Wessells et al. 1998 (J Urol)

500-1000 mcg

As needed

Reconstitution CalculatorU-100

Vial strength

BAC water

Target dose

050100u

Draw to

— units

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How it works

MT-II binds melanocortin receptors throughout the body. MC1R activation on melanocytes stimulates melanogenesis (eumelanin production), darkening skin and providing UV protection. MC3R and MC4R activation in the hypothalamus suppresses appetite and enhances sexual arousal and erectile function. The cyclic disulfide bridge between Cys4 and Cys10 constrains the peptide into a bioactive conformation with enhanced receptor binding affinity and enzymatic stability compared to linear MSH analogs. Effects on pigmentation are cumulative and persist for weeks after discontinuation due to melanin turnover kinetics.

What to expect

Early

Days 1–7

Days 1-7: Nausea and facial flushing after injection. Mild skin darkening may begin. Libido enhancement possible within first few doses.

Mid

Weeks 2–4

Weeks 2-4: Significant skin darkening, especially with UV exposure. Appetite suppression. Sexual function enhancement established.

Later

Weeks 4–12

Weeks 4+: Maintenance phase. 1-2x weekly dosing sustains pigmentation. Monitor moles. Color fades over 4-8 weeks if discontinued.

Evidence

HumanStrong

AnimalPresent

In-vitroPresent

2000Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II · Wessells H et al, International Journal of Impotence Research ↗peer reviewed

2005Discovery that a melanocortin regulates sexual functions in male and female humans · Wessells H et al, Peptides ↗peer reviewed

2006Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization · Hadley ME, Dorr RT, Peptides ↗review

2021Melanotan Tanning Injection: A Rare Cause of Priapism · Various, Cureus ↗case report

The honest take

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Tanning without UV

Confirmed. MT-II increases melanin production independent of UV exposure. UV exposure accelerates and enhances the effect but is not required.

Sexual function

Supported

Confirmed in human studies. MC3R/MC4R activation in hypothalamus enhances libido and erectile function. PT-141 (Bremelanotide) was derived from MT-II and is FDA-approved for this purpose.

Mole/melanoma risk

MT-II stimulates all melanocytes including those in moles. New mole formation and darkening of existing moles is documented. Direct melanoma causation is not proven but theoretical risk warrants monitoring.

Interactions & stacking

What's safe to combine, and what belongs in a separate pin.

Safe & synergistic

GlutathioneNOT syringe compatible - Glutathione is PIN ALONE (IM route, thiol group is oxidation-sensitive). However, safe to use on the same day in separate injections. Often listed as a pharmacological conflict due to opposing pigmentation pathways - MT-II stimulates eumelanin (darkening) while Glutathione shifts melanin toward pheomelanin (lightening). In practice, the skin-lightening effect of Glutathione requires sustained high doses (500-1000mg+ daily for months). At typical antioxidant/detox dosing (100-300mg every few days), Glutathione does not meaningfully oppose MT-II tanning.

Keep separate

GHK-CuCopper ions catalyze oxidation of MT-II's tryptophan at position 9 (Trp-9). Chemical incompatibility - never combine in syringe.

PT-141Both melanocortin agonists. Overlapping MC3R/MC4R activation. Space doses apart - do not use same day.

Side effects & safety

Commonly reported

Nausea (most common, dose-dependent)
Facial flushing
Appetite suppression
New or darkened moles/freckles

Less common & notes

Persistent erections (priapism risk at higher doses).
Darkening of existing moles requires dermatological monitoring.
Theoretical concern about melanoma promotion through melanocyte stimulation (not proven but monitor).
Elevated blood pressure transiently.
Fatigue or lethargy.
Stop and consult physician if moles change shape or color asymmetrically.

Pharmacokinetics

Illustrative plasma concentration · 24 h

Half-life

Peak · Tmax

0.5h

Elimination

Activity

6-12 hours (acute effects); melanogenesis persists for days to weeks

Storage. Cyclic disulfide bridge provides enhanced stability. 28-42 day reconstituted shelf life at 2-8C. Small doses mean vials last many weeks. Protect from light. Do not freeze after reconstitution.

Regulatory status

Not FDA-approved. PT-141 (derived from MT-II) is FDA-approved for HSDD. WADA prohibited under S2. Available through research and compounding channels. Multiple countries have issued warnings about unregulated MT-II use.

Put it to work

Calculate, log & track

Open MT-II straight into OnePin with your vial and dose pre-filled, then let it handle the syringe math and remind you before the vial runs out.

Open MT-II in the app →

Go deeper

The guide & community

The complete MT-II walkthrough, real protocol discussion and coaching live inside the BlessUp community on Skool.

Join the community ↗

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