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Melanotan II vs PT-141

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The key difference

Both act on melanocortin receptors. PT-141 (bremelanotide) was developed from melanotan II and is FDA-approved for low sexual desire in premenopausal women. Melanotan II is unapproved and is known mainly for tanning, alongside sexual and appetite effects.

Side by side

What it is
Melanotan IIA synthetic melanocortin agonist that stimulates melanin production for tanning, with notable secondary effects on libido and appetite. Non-selective across melanocortin receptors.
PT-141A melanocortin receptor agonist FDA-approved (as Vyleesi) for hypoactive sexual desire disorder in premenopausal women. Acts centrally on the brain rather than the vascular system.
Research status
Melanotan IIResearch chemical
PT-141Research chemical
Category
Melanotan IITanning & Skin
PT-141Sexual Health
Half-life
Melanotan IIApproximately 33-36 hours
PT-141Approximately 2-3 hours
Routes
Melanotan IIsubcutaneous
PT-141subcutaneous
Reported dosing
Melanotan IIResearch literature references a low-dose loading phase (~250-500 mcg daily) followed by maintenance dosing once tanning is achieved. Educational range only.
PT-141The approved product (Vyleesi) is 1.75 mg subcutaneously on demand, at least 45 minutes before activity, no more than once per 24 hours. Stated as labeled dosing.
Studied for
Melanotan II
  • Stimulates skin tanning with reduced UV exposure
  • May increase libido (MC4R activity)
  • Appetite suppression in some users
  • Some photoprotective effect from increased melanin
PT-141
  • Increases sexual desire and arousal via central pathways
  • FDA-approved (as Vyleesi) for HSDD in premenopausal women
  • Works independently of the vascular system
  • Effective in both men and women in research
Side effects
Melanotan II
  • Nausea and facial flushing
  • Darkening of existing moles and new freckles (monitor dermatologically)
  • Spontaneous erections in men
  • Appetite suppression and occasional dizziness
PT-141
  • Nausea (common, sometimes significant)
  • Flushing and headache
  • Transient increase in blood pressure
  • Darkening of skin or gums with repeated use (melanocortin activity)
Cited studies
Melanotan II4 on its page
PT-1415 on its page

How Melanotan II works

Melanotan II is a cyclic analog of alpha-MSH that non-selectively activates melanocortin receptors, including MC1R (skin pigmentation) and MC4R (libido and appetite). MC1R activation increases eumelanin synthesis in melanocytes, darkening the skin and providing some photoprotection. Its activity at MC4R explains the commonly observed effects on sexual arousal and reduced appetite.

Full Melanotan II profile →

How PT-141 works

PT-141 (bremelanotide) is a cyclic heptapeptide analog of alpha-MSH that activates melanocortin receptors, particularly MC4R, in the central nervous system. Unlike PDE5 inhibitors that work on blood flow, it modulates neural pathways governing sexual desire and arousal. This central mechanism allows it to influence libido directly through hypothalamic signaling.

Full PT-141 profile →

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