Bottom line
A boundary-case entry: Melanotan II is a single synthetic peptide (a cyclic alpha-MSH analog), not a blend. It is included here because it is frequently discussed in "stack" contexts alongside other peptides (PT-141/Bremelanotide, GH secretagogues) and illustrates the blurred line between single-compound and combination marketing in the research-peptide space.
No established or recommended human dose.
Name and formulation variability
| Observed source/date | Claimed components | Claimed amounts | Verification limits |
|---|---|---|---|
| Online-market listings observed in 2026 | Melanotan II (single peptide) | Variable | Seller-declared identity and amount are not independent verification |
| Online-market combination claims | Melanotan II with PT-141, GHRP-6, or other substances | Variable | No standardized "Melanotan II blend" exists and no combination efficacy or compatibility evidence was identified |
Melanotan II is a synthetic cyclic heptapeptide (Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂) developed as a non-selective melanocortin receptor agonist (MC1R, MC3R, MC4R, MC5R). It was originally investigated for skin tanning and sexual dysfunction but never received FDA approval.
Evidence for Melanotan II alone
| Domain | Evidence |
|---|---|
| Mechanism | Non-selective melanocortin receptor agonist; MC1R → melanogenesis; MC4R → erectile/apetite effects |
| Human trials | Phase I/II for tanning (Palatin Technologies); development discontinued after safety concerns |
| Approved status | Never FDA-approved; FDA issued import alerts |
| Safety signals | Melanocytic nevi changes, nausea, flushing, spontaneous erections, potential melanoma risk |
| WADA | Not explicitly named in the 2026 index; the S0 catch-all for non-approved pharmacological substances is relevant and athletes need a case-specific determination |
Why it appears in a blend atlas
Melanotan II is frequently promoted in combination "stacks": with PT-141 (bremelanotide, a related metabolite) for tanning/libido claims, or with GH secretagogues for body-composition claims. However, there is no standardized pre-formulated "Melanotan II blend" product and no basis for treating these marketing combinations as studied regimens.
This illustrates a broader pattern: many blends in the research-peptide market are not manufacturer-pre-formulated combinations but user-defined stacks that vendors encourage by selling multiple peptides from the same catalogue.
Regulatory and product-quality notes
FDA Import Alert 66-41 identifies Melanotan I and II in its scope; an import alert is an enforcement screening mechanism, not a marketing approval or a clinical safety determination
Multiple adverse event reports including melanocytic nevi changes and melanoma case reports
Sold as "research use only" with no pharmaceutical regulatory oversight
PT-141 (Bremelanotide) is FDA-approved as Vyleesi for hypoactive sexual desire disorder — a separate regulatory path from Melanotan II
Sources
FDA. Import Alert 66-41, "Unapproved New Drugs Promoted in the U.S." Product scope includes Melanotan I and II. https://www.accessdata.fda.gov/CMS_IA/importalert_190.html
PubChem. Melanotan II (CID 92432). https://pubchem.ncbi.nlm.nih.gov/compound/92432 accessed 2026-08-06.
Habbema L, et al. Melanotan II safety and side effects. Ned Tijdschr Geneeskd. 2012;156(40):A5134.
ClinicalTrials.gov. Melanotan II studies (various). Accessed 2026-08-06.
World Anti-Doping Agency. 2026 Prohibited List. https://www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf