Carl read the papersWhat it actually is
Melanotan I is a synthetic analogue of alpha-melanocyte stimulating hormone — the hormone that tells melanocytes to produce eumelanin, the dark protective pigment.
The distinction that matters is receptor selectivity. MT-2 hits several melanocortin receptors, including MC4R, which is where its libido and erection effects come from — along with much of the nausea and the flushing. MT-1 is selective for MC1R, the pigmentation receptor, and largely leaves the rest alone.
It is approved as SCENESSE (afamelanotide) for erythropoietic protoporphyria, a rare light-sensitivity disorder — one of very few compounds in this directory with genuine regulatory approval anywhere.
How it’s thought to work
- MC1R agonism — Selectively activates the melanocortin-1 receptor on melanocytes.
- Eumelanin synthesis — Shifts pigment production toward eumelanin, the darker and more photoprotective type.
- UV still required — This is the part people miss — MT-1 primes melanocytes but does not tan you on its own. Without UV exposure, very little happens.
- Shorter half-life — Cleared faster than MT-2, which is why daily dosing appears in loading protocols.
What the research says
Better documented than most of this shelf. Afamelanotide is approved for erythropoietic protoporphyria in the EU, US and Australia, with the trial base that approval requires — though delivered as a subcutaneous implant rather than an injection. The cosmetic tanning use is off-label and rests on community reporting rather than trials.
- Approved as SCENESSE (afamelanotide) for erythropoietic protoporphyria — a genuinely licensed indication.
- MC1R-selective, which is the mechanistic reason it lacks MT-2's libido and nausea profile.
- UV exposure is required for meaningful pigmentation — it primes rather than tans.
- Approved delivery is a controlled-release implant; injectable use is off-label.
Watch: Melanotan I explained
Video by The Future of Dermatology on YouTube. Not affiliated with Peptide Carl and not an endorsement — included because a second explanation of the same mechanism is often what makes it click.
Reported protocols
These are the doses the peptide community actually reports running (Reddit & forums), alongside published research — logged for education, not as a recommendation to use.
| Parameter | Commonly reported range |
|---|---|
| Loading | Community protocols describe roughly 50 mcg (1 unit on a U-100 syringe at 10 mg/2 mL) subcutaneously daily for about 7 days, or until colour starts appearing |
| Maintenance | 250 mcg (5 units) twice weekly, or weekly depending on sun exposure |
| Reconstitution | A 10 mg vial in 2 mL BAC water gives 5,000 mcg/mL — so 1 unit is 50 mcg and 5 units is 250 mcg |
| Cycle | Commonly described as 8 weeks on, 8 weeks off, with loading over 2–4 weeks |
| Route | Subcutaneous, rotating sites |
| Community tip | Two things come up constantly: UV is not optional — without exposure you get very little — and MT-1 is much slower than MT-2, which is exactly why people who have had a bad time on MT-2 switch to it. |
Common use cases
| Goal | Community protocol notes |
|---|---|
| Pigmentation with UV exposure | ~50 mcg daily loading for 7 days, then 250 mcg 2×/week |
| Switching from Melanotan II | same goal, MC1R-selective, no MC4R side effects |
| Light-sensitivity disorders | the approved indication — as a supervised implant, not vials |
Mixing it (reconstitution)
Freeze-dried peptides must be reconstituted with bacteriostatic water before they can be measured. Carl’s calculator turns “mg in the vial + ml of water + target dose” into “units on the syringe” — and tells you how long the vial lasts.
→ Open the Reconstitution Calculator
Injection & handling
Subcutaneous, rotating sites — abdomen and thigh are the usual choices. A 10 mg vial reconstituted with 2 mL BAC water gives 5,000 mcg/mL, which makes 1 unit on a U-100 insulin syringe 50 mcg. Loading protocols run around 50 mcg daily for a week, then move to 250 mcg twice weekly. Reconstituted, keep it cold and out of the light — melanocortin peptides are light-sensitive. And the part no protocol can substitute for: without UV exposure the pigmentation response is minimal regardless of dose.
Stacks it appears in
- Instead of Melanotan II — The usual reason people arrive here — same pigmentation goal, without MC4R side effects.
- With a copper peptide — GHK-Cu appears alongside it in skin protocols; different mechanism, no interaction data.
