Overview
Choose your reading level:
In plain language
Melanotan II is a lab-made, ring-shaped peptide of 7 amino acids that copies a natural hormone that darkens skin. It was created at the University of Arizona in the 1990s as a possible "sunless tan."
It also affects appetite and sexual function, which led to the approved drug bremelanotide. Melanotan II itself was never approved. Health regulators have warned about products sold online, and reported problems include nausea, blood pressure effects and changes to moles.
For students
Melanotan II (about 1,024 Da) is a cyclic lactam analogue of alpha-MSH developed by Victor Hruby and Mac Hadley. It is a potent, nonselective agonist at melanocortin receptors MC1R, MC3R, MC4R and MC5R.
MC1R activation in melanocytes increases eumelanin production (tanning). MC4R activation in the brain affects sexual arousal and appetite. Early small human studies reported tanning, along with spontaneous erections, nausea and facial flushing.
For researchers and instructors
Relationship to bremelanotide. Bremelanotide is closely related to melanotan II, differing mainly at the C-terminus (a free acid rather than an amide).
Safety signals. Case reports describe new or changing moles, and melanoma has been reported in users, though causality is not established. Other reports include priapism and kidney problems. Product identity and purity from unregulated sellers are unknown.
Regulatory. Not approved anywhere for tanning. Regulators including the FDA have warned consumers about these products.
Molecular identity
- Amino acids
- 7 (cyclic)
- Molecular weight
- ~1,024.2 Da
- Formula
- C₅₀H₆₉N₁₅O₉
- Sequence
- Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂
Origin and history
Melanotan II was developed at the University of Arizona in the late 1980s and 1990s by Mac Hadley, Victor Hruby and colleagues. Their goal was a “sunless tan” to protect fair-skinned people from skin cancer.
Early trials showed it caused tanning and, unexpectedly, erections. That finding led to bremelanotide. Its sister peptide, melanotan I (afamelanotide), was approved in 2019 as Scenesse for a rare light-sensitivity disorder. Melanotan II itself was never approved, and health agencies have warned against unlicensed tanning injections.
Key people
- Mac HadleyUniversity of Arizona
- Victor HrubyPeptide chemist, University of Arizona
Timeline
- 1980s
Melanotan program begins in Arizona
- 1996
First human study of melanotan II
- 1998
Erectile effects reported
- 2019
Related melanotan I approved as Scenesse
See every peptide on one history timeline.
Human evidence
Only small early human studies exist; it was not developed into an approved drug.
Registration and enrollment are not proof of benefit; check study results directly.
Explore original publications and distinguish preclinical findings from controlled human evidence.
Safety and regulatory status
See every compound on the regulatory tracker.
Not approved. The FDA and other regulators have warned about unapproved melanotan products sold online; reported problems include nausea, blood pressure effects and changes to moles.
This profile is educational and does not provide treatment, dosing or sourcing guidance.
Sources
- PubMed literature search: Melanotan II
- PubChem compound search: Melanotan II
- PubMed: melanotan II
- ClinicalTrials.gov search: Melanotan II
Hernandez Gener, E. (2026, November 7). Melanotan II: molecular data, research history and evidence. VALREXA Biosciences. https://valrexa.com/peptides/melanotan-ii.html
APA style · Last reviewed November 7, 2026 · Our editorial standardsLast reviewed November 7, 2026. Trial and regulatory status can change; confirm in the linked registries. This profile is educational and is not medical advice, a treatment recommendation, or dosing or sourcing guidance. Report an error · Corrections policy