PT-141 vs melanotan II

Two melanocortin agonists constantly confused — one an approved drug for sexual desire, the other an unapproved tanning peptide whose libido effects are a side effect.

One is approved; one carries real safety concerns. PT-141 is a licensed medicine; melanotan II is an unapproved research chemical with documented risks including mole changes and melanoma reports. This is a factual comparison, not advice, and not a recommendation to use either.

	PT-141Bremelanotide, Vyleesi	Melanotan IIMTII
What it is	Approved sexual-desire drug	Unapproved tanning peptide
Receptor	Melanocortin MC4R	Melanocortin MC1R + MC4R
Used for	Low sexual desire (HSDD, women)	Skin tanning; libido as a side effect
Route	subcutaneous (abdomen or thigh)	subcutaneous; on the grey market also intranasal
Half-life	~2.7 hours	~30–60 minutes
Key risk	Nausea, transient blood-pressure rise	Mole changes, melanoma reports, priapism
Status	Approved	In trials

PT-141 (bremelanotide, Vyleesi)

An approved melanocortin agonist for low sexual desire (HSDD) in premenopausal women, acting on the brain’s MC4R pathway rather than on blood flow. Use in men, or for erectile dysfunction, is off-label. It is the studied, regulated option of the two.

Melanotan II

An unapproved melanocortin agonist whose intended effect is skin tanning (via MC1R); the libido and erection effects that get it discussed alongside PT-141 are a side effect of its MC4R activity. It comes with real safety concerns — mole darkening, melanoma reports, nausea and priapism — and is sold as an unregulated powder of unknown purity.

PT-141 & melanotan II: common questions

What is the difference between PT-141 and melanotan II?

Both are melanocortin agonists, but only PT-141 is an approved drug — for low sexual desire in women. Melanotan II is an unapproved tanning peptide; its libido and erection effects are a side effect of hitting the same MC4R receptor, and it also carries real safety concerns.

Is melanotan II safe?

It is not an approved drug, and there are documented concerns — nausea, changes to moles and reports of melanoma, spontaneous erections (priapism) and systemic effects. It is sold as an unregulated research chemical of unknown purity. This site does not recommend its use.

Which is better for erectile dysfunction or libido?

PT-141 is the one actually studied and approved for a desire disorder (in women; use in men is off-label). Melanotan II’s sexual effects are incidental to its tanning purpose and come bundled with its safety problems. Neither is a first-line treatment, and nothing here is medical advice.

Are PT-141 and melanotan II legal?

PT-141 (Vyleesi) is an approved prescription medicine in the US; melanotan II is not approved anywhere and is sold as a research chemical. Prescription status is separate from whether an online source is lawful — see legal status.

PT-141 · Melanotan II · Hormonal & sexual hub · Legal status