Melanotan II Reconstitution: Dose to Syringe Units
Last updated: July 2026
To reconstitute a melanotan II vial you add bacteriostatic water to the dry powder, work out the concentration in micrograms per millilitre, then divide your intended dose by that concentration to get the volume — which on a U-100 insulin syringe reads directly as units. A 10 mg vial made up with 2 mL of BAC water becomes 5 mg/mL, or 50 mcg per unit, so a 250 mcg dose is exactly 5 units.
Have a vial and a target dose? Skip the arithmetic and get exact mL and U-100 units instantly.
Open the peptide reconstitution calculator →Important honesty note first. Melanotan II is not an approved medicine anywhere. It is an unlicensed, research-grade α-melanocyte-stimulating hormone analogue sold online, and national health agencies have issued repeated safety warnings about it. Documented harms in the medical literature include new and changing moles, at least one reported melanoma, nausea, and cases of systemic toxicity and rhabdomyolysis. This page explains the reconstitution arithmetic only — it is a maths reference, not medical advice, and not an endorsement of use.
TL;DR — key takeaways
- Concentration is everything. Units depend on how much BAC water you add, not on the drug. The same 10 mg vial can read 2.5 units or 12.5 units for the identical dose.
- The formula never changes. concentration (mcg/mL) = vial mcg ÷ mL of water; units = dose mcg ÷ (concentration ÷ 100).
- Peptides are dosed in micrograms. 1 mg = 1000 mcg, and doses are typically a few hundred mcg, so small unit counts are normal.
- Regulated cousin exists. Afamelanotide (Scenesse) is an FDA-approved α-MSH analogue for a rare light-sensitivity disorder — melanotan II is the unregulated, self-injected version and is not the same thing.
What melanotan II is, in one paragraph
Melanotan II is a synthetic cyclic heptapeptide that mimics α-MSH and binds melanocortin receptors, stimulating melanin production so the skin darkens with less ultraviolet exposure. It was first studied in a small phase-I trial in the 1990s, but that early work also flagged nausea, yawning and stretching even at low doses, and it was never developed into an approved product. Everything sold today under the name "melanotan II" or "MT-2" is an unregulated powder of uncertain purity. Because purity and true fill weight vary, the numbers below assume the vial contains what its label claims — an assumption you cannot actually verify at home.
The reconstitution formula
Two facts drive every calculation. First, a U-100 insulin syringe holds 100 units per 1 mL, so 1 unit = 0.01 mL. Second, concentration is simply drug divided by liquid. Put together:
- Concentration (mcg per unit) = (vial mg × 1000) ÷ (mL of BAC water × 100)
- Units to draw = dose in mcg ÷ concentration in mcg per unit
That is the entire method. There is no melanotan-specific constant — the same maths applies to any lyophilised peptide you reconstitute.
Reconstitution reference chart (10 mg vial)
How a single 10 mg melanotan II vial reads at four common BAC-water volumes. Always confirm against your own vial's stated weight.
| BAC water added | Concentration | Per unit | 250 mcg dose | 500 mcg dose |
|---|---|---|---|---|
| 1 mL | 10 mg/mL | 100 mcg | 2.5 units | 5 units |
| 2 mL | 5 mg/mL | 50 mcg | 5 units | 10 units |
| 2.5 mL | 4 mg/mL | 40 mcg | 6.25 units | 12.5 units |
| 5 mL | 2 mg/mL | 20 mcg | 12.5 units | 25 units |
Notice the pattern: double the water and you halve the concentration, which doubles the units for the same dose. More water is not "more drug" — it just spreads the same milligrams across more volume, giving you finer, easier-to-read gradations on the syringe.
Reading the draw on a U-100 syringe
At 50 mcg per unit, a 250 mcg dose sits at the 5-unit mark — a tiny volume near the bottom of the barrel.
Worked examples
Example 1 — standard 2 mL mix
10 mg vial + 2 mL BAC water → 5 mg/mL = 50 mcg per unit. A 250 mcg dose: 250 ÷ 50 = 5 units.
Example 2 — larger dose, same vial
Same 5 mg/mL vial, but a 500 mcg dose: 500 ÷ 50 = 10 units. Double the dose, double the units — concentration unchanged.
Example 3 — minimal water
10 mg vial + 1 mL BAC water → 10 mg/mL = 100 mcg per unit. A 300 mcg dose: 300 ÷ 100 = 3 units — a very small, hard-to-measure draw.
Example 4 — dilute for finer control
10 mg vial + 5 mL BAC water → 2 mg/mL = 20 mcg per unit. A 200 mcg dose: 200 ÷ 20 = 10 units. The extra water spreads the dose over more marks, so small changes are easier to read.
Example 5 — units back to micrograms
On a 5 mg/mL (50 mcg/unit) vial, what does an 8-unit draw contain? 8 × 50 = 400 mcg. Reverse the arithmetic any time you want to check a mark.
Example 6 — how many doses per vial
A 10 mg (10,000 mcg) vial dosed at 250 mcg contains 10,000 ÷ 250 = 40 doses — independent of how much water you added, because total drug is fixed.
How this is calculated
Every figure on this page comes from two constants and nothing else: a U-100 syringe is 100 units per millilitre, and concentration equals total micrograms divided by total millilitres. We never invent a drug-specific factor and we never assume a "correct" dose — the dose is whatever number you put into the formula. This is deliberately honest arithmetic; there is no clinical review of a protocol here, because self-dosing an unlicensed compound is not something this tool endorses or can make safe.
Safety, told straight
The reason the maths is easy but the decision is not: melanotan II has a genuinely worrying case-report record. Dermatology journals describe eruptive and darkening moles within a day of injection, dysplastic naevi, and melanoma linked to use; toxicology reports describe rhabdomyolysis and sympathomimetic crises after larger doses. Purity of black-market powder is unknown, and there is no manufacturer, batch testing, or recall system behind it. Knowing how to convert 250 mcg to 5 units does not change any of that. If you are weighing this compound, that is a conversation for a licensed clinician, not a calculator.
Frequently asked questions
Does more BAC water make melanotan II stronger?
No. Water changes only the concentration, not the total drug. A 10 mg vial holds 10 mg whether you add 1 mL or 5 mL; more water simply means more units for the same dose, and finer gradations on the syringe.
Why is the dose in micrograms, not milligrams?
Peptide doses are small — typically a few hundred micrograms. Since 1 mg = 1000 mcg, working in micrograms keeps the numbers whole and avoids decimal-place errors when you convert to units.
Is melanotan II the same as the FDA-approved afamelanotide?
No. Afamelanotide (Scenesse) is a regulated, implanted α-MSH analogue prescribed for a rare photosensitivity disorder under medical supervision. Melanotan II is the unlicensed, self-injected version and has not been approved or quality-tested.
How do I check my units are right?
Reverse the arithmetic: multiply your unit count by the mcg-per-unit figure for your vial. If that product matches your intended dose in micrograms, the draw is correct. The calculator does this both ways automatically.
Sources
- Dorr RT, et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study (Life Sci 1996)
- Ong S, Bowling J. Melanotan-associated melanoma in situ (Australas J Dermatol 2012)
- Cousen P, Colver G, Helbling I. Eruptive melanocytic naevi following melanotan injection (Br J Dermatol 2009)
- Melanotan II injection resulting in systemic toxicity and rhabdomyolysis (Clin Toxicol 2012)
- Eruptive naevi and darkening of pre-existing naevi 24 h after a single mono-dose injection of melanotan II (2013)
- A glimpse into the underground market of melanotan (2018)
- Consider underlying body dysmorphic disorder in users of melanotan (Br J Dermatol 2009)
- Changes of melanocytic lesions induced by Melanotan injections and sun bed use in a FAMMM-syndrome patient (Dermatol Pract Concept, PMC)
- SCENESSE (afamelanotide) implant, Prescribing Information (DailyMed / FDA label)
This guide is for general educational purposes only and does not constitute medical advice. Always follow your prescriber’s specific instructions and consult a qualified clinician before changing any protocol.