Head to head
Melanotan I vs Melanotan II
Two compounds that are more often stacked than compared — the side-by-side data, and what actually separates them.
Verdict
Not an either/or
What you are actually choosing between
Before anything else: the dataset lists Melanotan I and Melanotan II in each other's stacks. They are run together more often than they are chosen between, so if you came here for a winner, the first honest answer is that this may not be an either/or.
Both are classed here as cosmetic compounds, so this is a within-class choice: the mechanism is broadly shared and what separates them is kinetics, route, and how much has actually been tested.
The overlap is skin and hair. On this site's goal weighting — an editorial priority score, not a measure of effect size — Melanotan I rates 4/5 for skin and hair and Melanotan II rates 4/5. Outside that overlap only Melanotan II goes further, carrying weight for sexual function; Melanotan I's declared goals stop at the overlap.
The evidence
Neither compound reduces to a clean evidence tier here, so read both notes below rather than trusting a label.
How they differ in practice
No half-life is published for either compound in this dataset. That absence is itself information: it means the pharmacokinetics have not been characterized well enough to quote, so both dosing schedules — once daily for Melanotan I, once daily for Melanotan II — are convention.
Source notes
What the evidence actually says
Verbatim, so you can check the verdict above against what it was built from.
Melanotan I (Afamelanotide)
DO NOT CONFLATE THIS WITH MELANOTAN II — that is the single most common error made about this compound, and the two behave differently enough that the mistake matters. Melanotan I is the LINEAR alpha-MSH analogue [Nle4-D-Phe7]-alpha-MSH (afamelanotide): a 13-amino-acid straight-chain peptide that is essentially alpha-MSH with two residues swapped for stability, and it is relatively SELECTIVE FOR MC1R, the melanocyte receptor. Melanotan II is a smaller CYCLIC seven-residue peptide that hits MC1R, MC3R, MC4R and MC5R non-selectively. The MC3R/MC4R activity is where Melanotan II gets its spontaneous erections and priapism reports, its heavy nausea and vomiting, its yawning/stretching reaction and its appetite suppression. MELANOTAN I DOES NOT SHARE THAT PROFILE: it is not an erectogenic drug (that pharmacology is what PT-141/bremelanotide was developed from, and bremelanotide is a Melanotan II derivative, not a Melanotan I derivative), and its nausea and appetite effects are much weaker. What it does share is melanogenesis, and therefore the mole and melanoma-surveillance concern. THE APPROVAL STATUS IS ALSO DIFFERENT, AND THIS IS THE OTHER HALF OF THE CONFUSION. Afamelanotide IS an approved medicine: as SCENESSE it holds EMA approval (2014) and FDA approval (2019) for erythropoietic protoporphyria (EPP), a rare inherited photosensitivity disorder, where it increases eumelanin and raises the time patients can tolerate light exposure. Melanotan II is approved nowhere. That approval does NOT transfer to cosmetic use. The approved product is a 16 mg controlled-release SUBCUTANEOUS IMPLANT inserted by a trained clinician above the hip every two months, in a monitored EPP program that includes regular skin surveillance. It is not a self-injected lyophilized vial and it is not a nasal spray. The vials and sprays sold as "Melanotan 1" are unlicensed research-chemical product of unverified purity, with no approved label to anchor dosing to. The 250-1000 mcg daily figures here are grey-market convention only: Melanotan I is generally used at higher milligram totals than Melanotan II because it is less potent per microgram at MC1R uptake in practice, typically a daily loading phase until the target pigmentation is reached, then a much less frequent maintenance dose. Published pharmacokinetic figures for the free peptide are inconsistent and the implant PK is dominated by the release rate rather than the peptide, so no half-life is listed. Anyone using it should have a dermatologist skin check before starting and be monitored during and after, and it does not replace sun protection.
Melanotan II
Melanotan II is a non-selective melanocortin receptor agonist that drives melanogenesis. It is NOT approved as a medicine in any country. It never completed phase 3 development, the FDA has issued warning letters over its sale, and everything available is unlicensed research-chemical or grey-market product of unverified purity and dose. There is no approved label to anchor dosing to, so the numbers here describe common community practice only: roughly 250 mcg daily as a loading phase until the desired pigmentation is reached (commonly 1-4 weeks), then 500-1000 mcg once or twice weekly as maintenance. The stored daily frequency reflects that loading phase; step down once you stop the load. Reported half-life figures in the literature conflict badly (from about half an hour to several hours) and no regulatory pharmacokinetic package exists, so none is listed. THE MELANOMA CONCERN IS THE HEADLINE, NOT A FOOTNOTE. Dermatology case series and case reports describe eruptive melanocytic naevi, rapid darkening and dermoscopic change in existing moles, atypical/dysplastic naevi, and melanoma including melanoma in situ associated with Melanotan use. A personal or family history of melanoma, dysplastic or atypical naevi, or many moles is a conventional reason not to use it at all - that is what the active-malignancy flag on this entry is standing in for, since the dataset has no melanoma-specific flag. Anyone using it should have a full skin check by a dermatologist before starting and be monitored during and after. It does not remove the need for sun protection, and it is frequently combined with sunbeds, which compounds the risk.
Side by side
The numbers
| Attribute | Melanotan I | Melanotan II |
|---|---|---|
| Class | Cosmetic | Cosmetic |
| Routes | Subcutaneous, Intranasal | Subcutaneous, Intranasal |
| Dose range | 250 mcg–1 mg (typical 500 mcg) | 250 mcg–1 mg (typical 250 mcg) |
| Frequency | Once daily | Once daily |
| Half-life | Not characterized | Not characterized |
| Cycle length | 4 weeks | 4 weeks |
| Experience | Advanced | Advanced |
| Evidence | See note | Limited human data |
| Contraindications |
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| Side effects |
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Turn a typical dose into a mark on the syringe: Melanotan IMelanotan II
Goals
Where they overlap, and where they do not
| Goal | Melanotan I | Melanotan II |
|---|---|---|
| skin and hair | Melanotan I: 4/5 | Melanotan II: 4/5 |
| sexual functionone only | Melanotan I: — | Melanotan II: 3/5 |
They overlap on 1 goal and diverge on 1. Weights are this site’s editorial priority score out of 5 — how central a goal is to why people use a compound. They are not effect sizes and two 5s do not mean two equal results.
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Educational information only, not medical advice. Talk to a licensed clinician before starting, changing, or stopping anything.