Afamelanotide vs Melanotan II
Last updated: October 3, 2026 · 5 min read · By the Grey Peptides Editorial Board
- Afamelanotide, once known as melanotan I, is FDA-approved as Scenesse for a rare painful light sensitivity, erythropoietic protoporphyria.
- It targets the MC1 receptor on pigment cells; melanotan II acts across the melanocortin family, which brings sexual and appetite effects too.
- Melanotan II has never completed a proper trial, and case reports describe kidney injury.
- An approved implant for a rare disease is not evidence that a cosmetic tanning injection is safe.
Side by side
Afamelanotide High and melanotan II Low were developed from the same research on synthetic versions of alpha-MSH, the hormone that darkens skin 1. The table is read from our encyclopedia entries.
| Field | Afamelanotide | Melanotan II |
|---|---|---|
| Encyclopedia entry | Afamelanotide Mid-length entry | Melanotan II Full entry |
| Molecule class | Peptide | Peptide |
| Category | Sexual Health | Sexual Health |
| FDA status | FDA Approved | Research Chemical |
| Approved elsewhere | None recorded | None recorded |
| Evidence grade | High | Low |
| Half-life | ≈ 15 hours | Not measured in humans |
| Formula | C78H111N21O19 | C50H69N15O9 |
| Molecular weight | 1,646.8 g/mol | 1,024.2 g/mol |
| WADA 2026 | Not on the 2026 List | Prohibited (S0 catch-all) |
| WADA 2027 | Not on the 2027 List | Prohibited (S0 catch-all) |
| In one line | An FDA-approved selective MC1R agonist marketed as Scenesse — the first-in-class treatment for erythropoietic protoporphyria (EPP), delivered as a subdermal implant. | An unapproved melanocortin agonist sold as a tanning and libido injection, with small 1990s trials and case reports of changing moles, melanoma, priapism and kidney injury. |
| Mechanism | Selective agonist at MC1R on melanocytes, upregulating tyrosinase activity and driving eumelanin synthesis. The increased eumelanin pigmentation absorbs and dissipates UV and visible-light photons, providing photoprotection in EPP patients whose porphyrin accumulation causes severe light-induced pain. Unlike melanotan II, afamelanotide is linear and MC1R-selective, avoiding MC3R/MC4R-mediated nausea and sexual side effects. | Non-selective agonist at MC1R (melanocyte stimulation → melanin production and tanning), MC3R and MC4R (central — appetite suppression and sexual arousal via hypothalamic pathways), and MC5R (sebaceous gland stimulation). The central MC4R agonism underlies both the increased libido/spontaneous erections reported by users and the adverse effects (nausea, yawning, flushing). MC1R agonism drives eumelanin synthesis but also stimulates melanocyte proliferation — the likely mechanism behind the mole changes and atypical nevi reported in case series. |
| Sources in the entry | 5 | 20 |
| Study cards | None (short entry) | 14 |
| Dosage page | None | Dosage page |
Afamelanotide: an approved implant for a rare disease
FDA approved afamelanotide on October 8, 2019 as Scenesse, a 16 mg controlled-release implant placed under the skin every two months, to increase pain-free light exposure in adults with a history of phototoxic reactions from erythropoietic protoporphyria (EPP), a rare genetic condition in which sunlight causes severe pain 1. In trials of 94 US and 74 EU patients, median pain-free time in direct sun was 69.4 against 40.8 hours over six months in the US trial and 6.0 against 0.8 hours over nine months in the EU trial (randomised trials) 2. A drug review describes it as the first MC1 receptor agonist, approved in the EU for preventing phototoxicity in adults with EPP (review) 3.
Early work under its old name, melanotan I, showed that the dose given under the skin was fully absorbed while nothing was detectable after oral dosing, with an elimination half-life of 0.8 to 1.7 hours and darkening of the skin (human study) 4. It has also been tested off-label: in 55 adults with vitiligo, adding a monthly implant to light therapy sped repigmentation (randomised trial) 5, a use that is not approved.
Melanotan II: an unselective tanning peptide
Melanotan II acts broadly across melanocortin receptors (laboratory study) 6, which is why it affects appetite and sexual function as well as pigment. In three healthy men, two developed increased pigmentation after two weeks of injections (human study) 7; in 20 men with erectile dysfunction, it produced erections without stimulation in most, with nausea and yawning common (small human studies) 8. A 2020 case report attributed a kidney infarction to it and reviewed earlier reports of rhabdomyolysis and kidney failure (case reports) 9, and online vials labelled 10 mg held 4.32 to 8.84 mg (laboratory analysis) 10.
Why one was approved and the other was not
The difference is not just chemistry; it is the programme behind each. Afamelanotide was developed for a specific, measurable medical problem, pain from light in EPP, tested in randomised trials against placebo and approved with a defined implant dose and schedule 2 1. Melanotan II was never taken through that process; its human evidence stops at studies of a few people 7 8. Its broader receptor activity also means a tan comes bundled with nausea, appetite changes and sexual effects 8.
Afamelanotide's approval does not cover cosmetic tanning, and it does not make melanotan II safer by association. People sometimes buy melanotan II believing it is 'the approved tanning peptide'; it is not, and the product sold online is not even reliably the dose on the label 10.
Questions to ask before choosing either
- Do I have erythropoietic protoporphyria, for which an approved implant exists through specialist care?
- Is the product an approved implant, or an online vial of an unapproved peptide?
- Do I have kidney disease? Case reports link melanotan II to kidney injury.
- Am I subject to anti-doping rules?
How the differences add up (as of October 3, 2026)
Afamelanotide is a selective, approved medicine for a rare disease, backed by randomised trials. Melanotan II is an unselective, unapproved peptide with tiny studies, serious case reports and a quality problem in what is sold. For sport, afamelanotide is not on the WADA list; melanotan II falls under S0 by our reading 1. Our PT-141 vs melanotan II page covers melanotan II's other approved relative. Doses on this page are those in our entries' sources, not recommendations.
Frequently asked questions
Is afamelanotide the same as melanotan I?
Yes. Afamelanotide was earlier called melanotan I. It is FDA-approved as the Scenesse implant for erythropoietic protoporphyria.
Is melanotan II approved for tanning?
No. Melanotan II is not approved for any use. Afamelanotide is approved only for erythropoietic protoporphyria, not cosmetic tanning.
What is the difference between melanotan I and II?
Melanotan I (afamelanotide) targets the MC1 receptor on pigment cells; melanotan II acts across several melanocortin receptors, which also affects appetite and sexual function.
Related on Grey Peptides
Sources
- Grey Peptides dataset records for afamelanotide (Scenesse, FDA-approved October 8, 2019) and melanotan II (not approved; WADA S0 inferred), studied doses as sourced on each entry; read October 3, 2026.
- Langendonk, J. G., et al. (2015). Afamelanotide for Erythropoietic Protoporphyria. N Engl J Med, 373(1), 48-59. PMID: 26132941
- Kim, E. S., et al. (2016). Afamelanotide: A Review in Erythropoietic Protoporphyria. Am J Clin Dermatol, 17(2), 179-85. PMID: 26979527
- Ugwu, S. O., et al. (1997). Skin pigmentation and pharmacokinetics of melanotan-I in humans. Biopharm Drug Dispos, 18(3), 259-69. PMID: 9113347
- Lim, H. W., et al. (2015). Afamelanotide and narrowband UV-B phototherapy for the treatment of vitiligo: a randomized multicenter trial. JAMA Dermatol, 151(1), 42-50. PMID: 25230094
- Tomassi, S., et al. (2022). CLIPSing Melanotan-II to Discover Multiple Functionally Selective hMCR Agonists. J Med Chem, 65(5), 4007-4017. PMID: 35188390
- Dorr, R. T., et al. (1996). Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci, 58(20), 1777-84. PMID: 8637402
- Wessells, H., et al. (2000). Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II. Int J Impot Res, 12 Suppl 4, S74-9. PMID: 11035391
- Peters, B., et al. (2020). Melanotan II: a possible cause of renal infarction: review of the literature and case report. CEN Case Rep, 9(2), 159-161. PMID: 31953620
- Breindahl, T., et al. (2015). Identification and characterization by LC-UV-MS/MS of melanotan II skin-tanning products sold illegally on the Internet. Drug Test Anal, 7(2), 164-72. PMID: 24771717
Educational information, not medical advice. Each dose in this guide names its source, an approved label or a published study. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose.
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