Melanotan II: research protocol, dosing & reconstitution
Also known as: MT-II, MT-2, Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2
Quick answer
What is Melanotan II?
Melanotan II is a lab-made, longer-lasting version of α-MSH — the hormone that tells skin to make pigment. It was studied in the 1990s for UV-free tanning and, unexpectedly, for erections; PT-141 was later derived from it. It is unapproved everywhere and is the peptide medicines regulators warn about most often.
What Melanotan II is
Melanotan II (MT-II) is a cyclic seven-amino-acid analogue of alpha-melanocyte-stimulating hormone. Chemists at the University of Arizona locked the peptide into a ring (a lactam bridge) so it survives longer in the body and binds the melanocortin receptorsReceptorA protein on or inside a cell that binds specific signaling molecules and triggers a response. Most peptides work by binding particular receptors.See glossary → far more strongly than the natural hormone [3].
Unlike the natural hormone it is non-selective: it activates the MC1 receptor on pigment cells, which drives tanning, and the MC3/MC4 receptors in the brain, which is why early volunteers reported yawning, nausea and spontaneous erections. That second effect was later split off into its own compound, bremelanotide (PT-141).
Mechanism of action
At the MC1 receptor on melanocytes, MT-II raises cyclic AMP and switches on eumelanin production — tanning without ultraviolet light. In the pilot phase I study, three male volunteers received 0.01 mg/kg subcutaneouslySubcutaneous (SubQ)An injection into the fatty tissue just below the skin. The most commonly referenced administration route in peptide research literature.See glossary → on weekdays for two weeks, escalating to 0.025–0.03 mg/kg; two were measurably darker a week after dosing ended, after as few as five low doses [1].
At the MC4 receptor the same molecule initiates erections. In a double-blind crossover study of ten men with psychogenic erectile dysfunction, a single 0.025 mg/kg dose produced clinically apparent erections in eight, with mean rigidity duration of 38 minutes versus 3 on placebo [2]. That observation is the origin of PT-141.
The safety literature is what sets MT-II apart. A 2017 review of unregulated α-MSH analogue use documents changes in existing moles, new naevi, and case reports of melanoma in users, against a background of internet supply with no quality control [4].
What researchers study Melanotan II for
- Melanocortin-receptor pharmacology (MC1R, MC3R, MC4R)
- UV-independent pigmentation and photoprotection models
- Sexual-arousal signalling — the origin of PT-141
- Appetite and energy-balance signalling via MC4R
What dose of Melanotan II do researchers use?
Research literature commonly references doses of 0.25–1 mg per dose (community reference); phase I trials used 0.01–0.03 mg/kg. This is not a recommendation — the table below summarizes protocols as they appear in published literature and trial designs.
| Context | Dose | Frequency | Duration |
|---|---|---|---|
| Phase I tanning study [1] | 0.01 mg/kg SC, escalated to 0.025–0.03 mg/kg (≈0.7–2 mg at 70 kg) | Once daily, Mon–Fri | 2 weeks |
| Erectile-function study [2] | 0.025 mg/kg SC | Single dose | 6-hour observation |
| Community “loading” reference | 0.25 mg first dose, then 0.5–1 mg | Once daily | 2–4 weeks referenced; no controlled trials |
| Community maintenance reference | 0.5–1 mg | 1–2× weekly | Ongoing; no established schedule |
← Swipe to see the full table
Half-life and dosing timing
Half-life: Short; not well characterised in humans — pigment effects outlast the peptide by weeks. Route referenced in research: Subcutaneous (research). The peptide itself clears quickly (its half-lifeHalf-lifeHow long it takes for half of a compound to be eliminated from the body. Half-life determines how often researchers dose a compound in protocols.See glossary → is not well characterised in humans), but pigmentation builds over days and persists for weeks — volunteers in the phase I study were still measurably darker a week after their last dose [1]. That lag is why community protocols split into a daily loading phase and a sparse maintenance phase, and why nausea and flushing cluster around the first few doses.
Titration: start low, go slow
The phase I study started at 0.01 mg/kg and escalated in 0.005 mg/kg steps; somnolence and fatigue appeared at 0.03 mg/kg [1]. Community protocols mirror that pattern with a 0.25 mg test dose before moving to 0.5–1 mg, which is the only real guidance the literature offers.
Skip the Melanotan II math
Enter vial size, water volume, and target dose — the free calculator returns concentration, injection volume, and exact U-100 syringe units.
How is Melanotan II reconstituted?
| Vial size | BAC water | Concentration | Worked example |
|---|---|---|---|
| 10 mg | 2 mL | 5,000 mcg/mL | 0.5 mg = 0.1 mL = 10 units on a U-100 syringe |
| 10 mg | 4 mL | 2,500 mcg/mL | 0.25 mg test dose = 0.1 mL = 10 units — more water makes small doses easier to draw |
Add 2 mL of bacteriostatic waterBAC water (bacteriostatic water)Sterile water containing 0.9% benzyl alcohol, which suppresses bacterial growth. It is the standard diluent used to reconstitute lyophilized peptides for multi-dose research vials.See glossary → to a 10 mg vialVialThe small sealed glass container peptides are supplied in, topped with a rubber septum that a syringe needle can pass through.See glossary →: 10 mg ÷ 2 mL = 5 mg/mL, or 5,000 mcgMicrogram (mcg / µg)One millionth of a gram, or one thousandth of a milligram. Most peptide research doses are measured in micrograms.See glossary →/mL. A 500 mcg (0.5 mg) dose is 500 ÷ 5,000 = 0.1 mL — 10 units on a U-100 syringeU-100 syringeAn insulin syringe calibrated so that 100 units equal 1 mL. The standard syringe referenced in peptide research; each unit equals 0.01 mL.See glossary →. A 250 mcg test dose from the same vial would be only 5 units; using 4 mL of water instead doubles that to a more accurate 10 units.
New to the process? Read the full step-by-step reconstitution guide.
How long does reconstituted Melanotan II last?
LyophilizedLyophilizedFreeze-dried. Peptides are shipped as a lyophilized powder ('puck') because the dry form is far more stable than a solution. It must be reconstituted before use in research.See glossary →: refrigerated and dark, stable roughly 12–24 months. ReconstitutedReconstitutionThe process of mixing a freeze-dried (lyophilized) peptide powder with bacteriostatic water to create a solution of known concentration.See glossary →: 2–8°C, protected from light, used within weeks. MT-II is more stable than the natural hormone by design, but the same cold, dark handling applies.
What is Melanotan II stacked with in research?
Rarely stackedPeptide stackTwo or more peptides used together in a research protocol because their mechanisms are complementary — for example, BPC-157 with TB-500.See glossary →. PT-141 is a derivative of MT-II with the pigmentation activity largely removed [3], so combining the two duplicates the melanocortin load rather than adding anything. KPV is the anti-inflammatory tail of the same parent hormone and is studied for the opposite reason — activity without pigmentation.
Side effects observed in research
Nausea, flushing, stretching and yawning, and spontaneous erections were reported at most dose levels in the phase I work [1]. The more serious concern is dermatological: darkening of existing moles, new naevi, and published case reports of melanoma in users of unregulated product [4]. It has no approval anywhere, medicines regulators in several countries have warned against its use, and it is sold strictly as a Research Use OnlyRUO (Research Use Only)A regulatory classification meaning a product is sold strictly for laboratory research and is not approved, labeled, or intended for human or veterinary use.See glossary → compound.
- Nausea and flushing, mostly at the first doses
- Stretching/yawning and spontaneous erections
- Darkening of existing moles and freckles
- New naevi; melanoma case reports in users
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Frequently asked questions
What dose of Melanotan II did clinical studies use?
The only controlled human studies used weight-based doses: 0.01–0.03 mg/kg in the tanning study and 0.025 mg/kg in the erectile-function trial [1][2] — roughly 0.7–2 mg for a 70 kg adult. The 0.25 mg → 0.5–1 mg protocols seen online are community convention, not trial data.
Is Melanotan II the same as PT-141?
No, but they are close relatives. PT-141 (bremelanotide) is a metabolite of MT-II that was developed after the erection effect was noticed in tanning volunteers [3]. PT-141 keeps the MC4R arousal activity with much less pigmentation.
Why do regulators warn about Melanotan II?
It has never been approved by any agency, so every product on the market is unregulated, and dermatologists have reported changes in moles, new naevi and cases of melanoma in users [4]. That combination — unapproved supply plus a direct effect on pigment cells — is why several national regulators have issued warnings.
Does Melanotan II work without sun exposure?
In the phase I study, yes: volunteers darkened measurably with only five low doses and no additional UV [1]. Community protocols usually describe pairing it with modest sun exposure to speed the effect, but the peptide drives pigment production on its own.
Related research peptides
SNAP-8
A topical 'expression-line' peptide that mimics part of the SNAP-25 protein, studied for softening wrinkles caused by muscle movement. Mixed into creams and serums — never injected.
Healing & RecoveryBPC-157
A synthetic peptide fragment studied for tissue repair, tendon/ligament and gut healing in animal research.
Healing & RecoveryTB-500
A synthetic version of a region of Thymosin Beta-4, studied for cell migration, angiogenesis and tissue repair.
Browse all Cosmetic peptides or start with the beginner’s guide to research peptides.
References
- 1.Dorr RT, et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci. 1996. PubMed ↗
- 2.Wessells H, et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. J Urol. 1998. PubMed ↗
- 3.Hadley ME, Dorr RT. Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization. Peptides. 2006. PubMed ↗
- 4.Habbema L, et al. Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review. Int J Dermatol. 2017. PubMed ↗