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 binds mainly to MC1R, the pigmentation receptor. It is not perfectly selective (lab work shows it binds other melanocortin receptors too), but erections are not on its side-effect list.
It is approved as SCENESSE (afamelanotide) for erythropoietic protoporphyria, a rare light-sensitivity disorder — one of the minority of compounds in this directory with a real regulatory approval somewhere.
How it’s thought to work
- MC1R agonism — Mainly activates the melanocortin-1 receptor on melanocytes.
- Eumelanin synthesis — Shifts pigment production toward eumelanin, the darker and more photoprotective type.
- UV helps, it isn't required: the FDA label says it raises eumelanin without sun or UV, and in a 1991 trial skin darkened even with sunscreen on. Sun on top adds to the effect.
- Short half-life — Injected, it clears in roughly 1 to 2 hours (one small study), 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, though early trials in healthy volunteers (1991 to 2006) did test it for tanning and sunburn protection.
- Approved as SCENESSE (afamelanotide) for erythropoietic protoporphyria — a genuinely licensed indication.
- Mostly MC1R, which is the likely reason it lacks MT-2's libido effects. Nausea still shows up (19% vs 14% on dummy implants in the label trials).
- Darkens skin without UV (the label says so), and sun on top adds to it.
- 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 speeds it up (trials show it darkens skin without sun, but sun adds to it), 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, mainly MC1R, no erection side effects on its label |
| 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. UV is not strictly needed (the label says it raises eumelanin without sun), but sun exposure adds to the response.
Stacks it appears in
- Instead of Melanotan II — The usual reason people arrive here — same pigmentation goal, without MT-2's erection side effects.
- With a copper peptide — GHK-Cu appears alongside it in skin protocols; different mechanism, no interaction data.
Sources
- Scenesse (afamelanotide) US label, DailyMed
- Drugs@FDA: Scenesse, NDA 210797 (approved 8 Oct 2019)
- EMA EPAR: Scenesse (authorised 22 Dec 2014, exceptional circumstances)
- Clinuvel: Australian TGA approves SCENESSE (27 Oct 2020)
- Afamelanotide phase 3 trials in EPP, NEJM 2015 (PMID 26132941)
- MT-1 tanning RCT with sunscreen, JAMA 1991 (PMID 1658407)
- MT-1 plus UV or sunlight, Arch Dermatol 2004 (PMID 15262693)
- MT-1 pigmentation and UV protection in fair skin, J Invest Dermatol 2006 (PMID 16763547)
- MT-1 pharmacokinetics in humans, Biopharm Drug Dispos 1997 (PMID 9113347)
- Melanocortin receptor binding of NDP-MSH, Eur J Pharmacol 1995 (PMID 7774675)
