Melanotan II Dosing Protocol

Melanotan II (often shortened to MT-II, MT-2, or MT2) is a lab-made peptide originally developed as a sunless tanning agent. Researchers at the University of Arizona created it in the 1980s-90s by modifying a natural hormone your body already produces called alpha-MSH, which controls skin pigmentation. The modifications made MT-II more potent and longer-lasting than the natural version.

What makes Melanotan II unusual is that it does not just affect tanning. Because it activates multiple receptors in the melanocortin system -- a group of signaling pathways involved in skin color, appetite, and sexual arousal -- it produces a mix of effects: darker skin, reduced appetite, and increased sexual desire. This broad activity is both its appeal and the source of its side effects.

Early clinical studies in the 1990s and 2000s tested MT-II for both tanning and erectile dysfunction. Those findings led researchers to develop a more targeted version called bremelanotide (PT-141), which was eventually FDA-approved for treating low sexual desire in women. Melanotan II itself was never refined for a single indication and was not submitted for FDA approval.

Melanotan II has never received FDA approval and remains an unregulated research compound. It is illegal to sell for human use in the US, UK, and Australia. This page is for educational and research reference only.

Melanotan II typically comes in 10 mg vials. The amount of bacteriostatic (BAC) water you add determines the concentration -- and therefore how much liquid you draw for each dose. The table below shows four common water volumes, the resulting concentration, and the exact syringe draw for doses from 250 mcg to 1 mg. Find the BAC water volume you plan to use in the left columns, then read across to your target dose.

Side effects are dose-dependent and commonly include nausea and flushing. Long-term safety remains uncertain in unregulated-use settings.

Common effects: Nausea, flushing, appetite suppression, fatigue, and yawning are frequently reported during initiation and dose escalation; severe nausea was reported in ED-dose trial contexts.

Sexual effects: Spontaneous erections and increased sexual desire can occur through central melanocortin signaling pathways.

Dermatologic concerns: MT-II can darken existing moles, freckles, and other pigmented spots on the skin. Case reports have documented new moles appearing and rapid changes in existing moles after MT-II use. Because changes to moles can sometimes indicate skin cancer (melanoma), anyone using MT-II should monitor their skin closely and consult a dermatologist if they notice moles changing shape, color, or size.

Serious events: Case reports include priapism (a prolonged, painful erection requiring medical attention) and severe toxicity from accidental overdoses, including rhabdomyolysis -- a dangerous condition where muscle tissue breaks down and can damage the kidneys. These events occurred at doses far above typical protocols.

Contraindication context: Risk-benefit concerns are elevated in individuals with melanoma history, uncontrolled cardiovascular disease, or priapism predisposition.

The table below summarizes the published human studies on Melanotan II. Most were small, early-phase studies conducted in the 1990s and early 2000s. They showed that MT-II works -- it darkens skin and affects sexual function -- but they also showed significant nausea at clinical doses. No large-scale modern trials have been conducted.

Here is the bottom line on MT-II's clinical evidence: early human studies confirmed that it produces real, measurable tanning and sexual-function effects. But the studies were small (20-100 participants), short-term, and accompanied by high nausea rates -- especially at the doses used for erectile dysfunction research. Rather than continuing to develop MT-II with its broad side-effect profile, researchers created more focused versions: afamelanotide for tanning (now FDA-approved for a rare skin condition) and bremelanotide (PT-141) for sexual function (FDA-approved for low sexual desire in women). Melanotan II itself was never submitted for FDA approval and has no ongoing clinical development.

Melanotan II, afamelanotide (Melanotan I), and PT-141 (bremelanotide) all come from the same research family -- they are all based on the natural hormone alpha-MSH. The key difference is specificity: MT-II hits multiple receptors and produces multiple effects, while the other two were designed to target one effect each. The table below compares them across structure, receptor targets, effects, dosing, and regulatory status so you can see how they differ.

These compounds share melanocortin ancestry but are not interchangeable due to receptor selectivity and clinical purpose differences.

MT-II has the broadest mixed-effect profile but also the broadest side-effect burden.

Afamelanotide and PT-141 advanced to regulated indications where MT-II did not.

See the PT-141 Protocol and Afamelanotide Protocol for compound-specific guides.