Melanotan II
(MT-II)

1980s

The Skin Cancer Problem

Seeking Safe Tanning

Skin cancer was rising. People wanted tans — they associated bronzed skin with health and attractiveness — but the UV exposure required caused melanoma. Scientists wondered: could you create a tan without the sun?

The body's natural tanning mechanism uses a hormone called alpha-MSH (melanocyte-stimulating hormone). When UV hits your skin, it triggers alpha-MSH release, which then stimulates melanocytes to produce melanin. The melanin is your tan — and your protection.

At the University of Arizona, researchers began designing synthetic versions of alpha-MSH that would be more potent and longer-lasting.

1991-1996

Creating MT-II

A Superpotent Peptide

Mac Hadley and Victor Hruby created Melanotan-2 — a cyclic peptide with seven amino acids that was far more potent than natural alpha-MSH. It was stable, long-lasting, and effective at stimulating melanin production.

Phase I clinical trials began. The peptide worked — subjects got tan without sun exposure. But something else happened too. Male subjects reported spontaneous erections. Both men and women reported increased sexual desire.

The researchers had stumbled onto something unexpected. Melanotan-2 was hitting melanocortin receptors throughout the body, not just in skin.

1996-2005

The Fork in the Road

Tanning Drug or Sexual Dysfunction Drug?

The sexual effects complicated things. For a tanning drug, they were unwanted side effects. But they opened another possibility: could Melanotan-2 or its derivatives treat sexual dysfunction?

Palatin Technologies licensed the technology and began developing a spin-off specifically for sexual function. This became PT-141 (later bremelanotide), modified to reduce tanning effects while preserving sexual function.

Meanwhile, the original tanning application faced challenges. The FDA wanted more safety data. The peptide had to be injected. Pharmaceutical development stalled. But online, something else was happening.

2005-2015

The Underground Phenomenon

When Research Compounds Go Viral

Melanotan-2 escaped the laboratory. People ordered it online, mixed it themselves, and injected it for tanning. They shared experiences on forums. The 'Barbie drug' — promising both tan skin and enhanced sexuality — developed a cult following.

Health authorities issued warnings. The peptide was unregulated, uncontrolled, and potentially dangerous. Contamination was possible. Long-term effects were unknown. Some users reported darkening of moles that raised cancer concerns.

But demand continued. People wanted what MT-II offered: a tan without UV damage, appetite suppression, increased libido. The peptide became a case study in how research compounds can bypass the pharmaceutical system.

2015-Present

Legitimate Applications Emerge

From Underground to FDA

Palatin's PT-141 (bremelanotide) won FDA approval in 2019 as Vyleesi for treating hypoactive sexual desire disorder in women. A derivative of Melanotan-2 had finally reached the legitimate market — not for tanning, but for sexual dysfunction.

Melanotan-2 itself remains unapproved and unregulated. Research continues into its various effects. Some scientists study it for eating disorders (appetite suppression). Others explore its role in protecting skin from UV damage. The melanocortin system touches so many functions.

The peptide designed to create safe tans became something more complex — a window into how a single molecular pathway can connect skin, brain, and behavior.