“Tanning peptide” leaves things out
Melanotan II, also called Melanotan 2 or MT-II, is a synthetic peptide that acts on melanocortin receptors. Receptors are the body's signal receivers. This family includes receivers involved in pigment, appetite and sexual function.
The history of melanocortin research follows that wider activity. A cosmetic goal doesn't narrow what a compound can do in the body. That's why we don't treat this name as just another skincare ingredient.
A small human study isn't a safety stamp
A study in men with psychogenic erectile dysfunction found erectile effects with Melanotan II. Participants also experienced nausea, stretching and yawning. “Psychogenic” means the erectile difficulty was linked to psychological factors.
The selected group and the study question matter. This was research on sexual function, not a test of long-term tanning safety. It shows activity beyond skin without telling everyone considering a cosmetic change that use would be safe.
Colour changes can be unwanted
A case report after Melanotan II injections describes pigment appearing inside a man's cheeks and on his gums. After he stopped, the cheek pigment began fading earlier. Some gum pigment was still present at follow-up.
So “it fades” would be too tidy a summary. This is one person's course, with different changes in different tissues. It can't tell us how often the same thing happens, or establish that a colour change will disappear.
Serious reports belong in the picture
A kidney-injury case report describes renal infarction: interrupted blood supply to part of the kidney. The authors considered Melanotan II a possible cause. That documents a serious concern without proving a general cause or giving a risk rate.
The FDA's Melanotan II safety entry also notes reports of melanoma and priapism, a prolonged erection. Those reports don't establish how often harm occurs. Priapism is a medical emergency; a new or changing mole needs clinical assessment.
Withdrawn doesn't mean approved
Melanotan II has no FDA-approved use. The FDA page carries an April 22, 2026 content date. Its Melanotan II entry sits under “nominated but withdrawn.” The people who nominated it for compounding took their request back; FDA still prints its safety concerns.
Taking back a request doesn't establish a right to compound the substance. FDA doesn't say when this particular request was withdrawn. Our comparison with GHK-Cu keeps their different effects and evidence in view, without turning either into a recommendation.