Melanotan II: What It Is and What the Evidence Shows

At a glance

What is Melanotan II?

Melanotan II is a synthetic cyclic peptide that activates several melanocortin receptors (MC1R, MC3R, MC4R, and MC5R), sometimes nicknamed "the Barbie drug." It is the structural parent from which the approved drug bremelanotide was derived. It is sold through gray-market channels as an injectable for tanning and sexual arousal, and it is not an approved medicine.

How does it work?

Melanotan II is proposed to work through two receptor effects: activating MC1R on skin cells to drive pigmentation and tanning, and activating MC4R in the brain, which is linked to sexual arousal and appetite. The sexual and appetite effects come largely from animal and early pharmacology work. This describes the proposed mechanism, separate from whether unregulated use for these purposes is effective or safe.

Is it FDA-approved?

No. Melanotan II is not approved by the FDA and is an unapproved drug; the FDA has previously issued warning letters targeting injectable tanning products containing melanotan. Its compounding nomination was withdrawn, so FDA removed it from its Category 2 list in April 2026 and lists it as nominated but withdrawn. The approved melanocortin drugs Scenesse (for a rare light disorder) and Vyleesi (for low sexual desire in certain women) are distinct, regulated products that Melanotan II is not.

What does the research show?

There are no controlled human trials supporting tanning or libido use. The published clinical literature consists mainly of case reports and clinician warnings. Reports have described new or changing moles and darkening of pigmented lesions after use of melanocortin tanning injections (example and example), and poison-center and dermatology sources describe nausea, flushing, and other effects. These are reports and warnings, not controlled trials, and unregulated product quality adds further uncertainty.

The first human data came from a 1996 pilot study in three healthy men, which reported:

It was a small drug-development study, not evidence that gray-market use is safe. The most serious skin report followed later: in one case report, a 20-year-old woman with fair skin developed melanoma after using it with a tanning bed.

Evidence strength

Low research: There is no controlled human evidence for the marketed uses, and the published literature consists of case reports and clinician warnings, including concerns about changes in pigmented skin lesions.

Sources: case reports of pigmented-lesion changes after melanocortin tanning injections (Cardones and Grichnik, Archives of Dermatology, 2009, DOI: 10.1001/archdermatol.2008.623; Cousen et al., British Journal of Dermatology, 2009, DOI: 10.1111/j.1365-2133.2009.09362.x), indexed on PubMed; and FDA warning communications on injectable tanning products. This document is educational, is not medical advice or a health claim, and is not an offer to sell any product.