Melanotan 2

Status Not approved for human use anywhere; sold as an unregulated research chemicalBest evidence E4Sources checked 2026-09-18

Melanotan II was never approved and has never completed a human trial for tanning or libido; it is the unmodified parent compound of two drugs (afamelanotide, bremelanotide) that were each derived from it specifically to remove one of its side effects. Case reports document priapism and concerning changes to existing moles.

What it is

Melanotan II (MT-II) is a synthetic cyclic alpha-MSH analogue and non-selective melanocortin receptor agonist, originally developed at the University of Arizona in the 1990s as a tanning and libido research compound. It is the parent molecule both Melanotan 1 (afamelanotide, FDA-approved as Scenesse) and PT-141 (bremelanotide, FDA-approved as Vyleesi) were derived from, each by a chemical modification made specifically to reduce a side effect associated with MT-II itself.

MT-II has never been approved for any use, in any country, and has never completed a registered human clinical trial for tanning, libido, appetite or any other indication. One Phase 2 trial (NCT07437560) was recruiting as of this entry, testing MT-II as an adjunct to phototherapy for vitiligo, a use unrelated to why it circulates.

The documented harms

Because MT-II circulates as an unregulated injectable, its adverse effects are documented mainly through case reports rather than trials. A published case report describes acute low-flow priapism after subcutaneous MT-II injection, managed with cavernosal aspiration and phenylephrine, with erectile function not yet recovered at four-week follow-up; the authors describe this as a previously unreported complication.

A separate case report describes a 16-year-old with a family history of atypical mole and melanoma syndrome (FAMMM) who developed darkening of multiple melanocytic nevi and an enlarging nevus after self-injecting Melanotan II and using UV tanning beds, prompting concern for malignant change. MT-II’s mechanism is direct stimulation of melanocyte activity; darkening or changing of existing moles is a mechanistically expected risk, not a coincidental one, and is the reason dermatology bodies have specifically warned against its use.

Nausea, flushing, and spontaneous erections are common and expected at typical doses, consistent with non-selective melanocortin receptor activation; MT-II’s persistent erection effect, more pronounced and longer-lasting than PT-141’s, is exactly what PT-141 was chemically modified to reduce.

What is not known

Any dose, purity or safety standard for MT-II as sold, since it has never been manufactured or studied as a regulated pharmaceutical product.

Long-term melanoma risk from repeated melanocyte stimulation. No long-term surveillance study of MT-II users was located; the concerning findings that exist are individual case reports.

What is not known

Any dose, purity or safety standard, since MT-II has never been manufactured or studied as a regulated pharmaceutical.

Long-term melanoma risk from repeated melanocyte stimulation. No surveillance study exists; the concerning findings on record are individual case reports.

Whether the priapism and mole-darkening effects documented in case reports are rare or common, since no systematic adverse-event reporting exists for an unregulated product.

Doses used in published research

No published study has administered this compound to a human being, so no dose appears in the literature and none has been established.

Amounts above record what a named source reported administering in a study. They are not a recommendation, not a protocol, and not instructions.

Converting a vial and a syringe into a draw volume is a separate, mechanical question from what amount to use. The reconstitution calculator does that arithmetic for peptide, HCG, and HGH vials.