Head-to-head
PT-141 vs Melanotan II
A field-by-field comparison of PT-141 and Melanotan II drawn from the PeptideIndex database: mechanism, evidence grade, half-life, administration route, reported dosing, side effects, storage and legal status. They belong to different categories — sexual health and skin & hair — so this page focuses on what each one actually does rather than which is "better".
PT-141 vs Melanotan II at a glance
| Attribute | PT-141 | Melanotan II |
|---|---|---|
| Category | Sexual health | Skin & hair |
| Evidence grade | Strong | Limited |
| Also known as | Bremelanotide, Vyleesi | MT-2 |
| Chain | Cyclic heptapeptide, Melanotan II metabolite | Cyclic heptapeptide α-MSH analogue |
| Mechanism | Selectively activates MC4R in the hypothalamus, increasing dopaminergic signalling in the medial preoptic area — driving desire itself rather than blood flow, unlike PDE5 inhibitors. | Non-selectively activates melanocortin receptors. MC1R activation drives melanogenesis; MC4R activation produces the appetite-suppressant and erectogenic effects. |
| Reported benefits | Increased sexual desire in both sexes · Works independently of vascular function · Effective as an on-demand dose | Increased melanin production and tanning · Appetite suppression · Increased libido and erectile function |
| Reported side effects | Nausea and vomiting · Flushing · Headache · Transient blood-pressure increase | Nausea and facial flushing · Darkening of existing moles and freckles · Spontaneous erections · Melanoma risk concerns |
| Half-life | About 2.7 hours | About 33 hours |
| Administration | Subcutaneous auto-injector, 45 minutes before activity | Subcutaneous injection |
| Dosing overview | 1.75 mg as needed, maximum one dose per 24 hours | Loading 250–500 mcg daily, then weekly maintenance |
| Storage | Room temperature for the approved auto-injector | Refrigerated after reconstitution |
| Legal status | FDA-approved (Vyleesi) for premenopausal HSDD; other uses are off-label. | Not approved anywhere; illegal to sell for human use in the UK, EU and US. |
Key differences between PT-141 and Melanotan II
Different categories, different goals
PT-141 is indexed under sexual health, while Melanotan II sits under skin & hair. They are not substitutes for one another: PT-141 is described as "An FDA-approved melanocortin agonist for hypoactive sexual desire disorder that works through the central nervous system rather than the vascular system." and Melanotan II as "A melanocortin agonist that stimulates tanning and libido — and the peptide most associated with real, documented harms."
Mechanism of action
PT-141: Selectively activates MC4R in the hypothalamus, increasing dopaminergic signalling in the medial preoptic area — driving desire itself rather than blood flow, unlike PDE5 inhibitors. Melanotan II: Non-selectively activates melanocortin receptors. MC1R activation drives melanogenesis; MC4R activation produces the appetite-suppressant and erectogenic effects.
Evidence quality is not equal
PT-141 carries a Strong evidence grade and Melanotan II a Limited grade on this index. The grade describes the quality of published human data, not how well a compound works — PT-141 has the better-documented record of the two, and claims made about Melanotan II rest on thinner human evidence.
Half-life and dosing frequency
PT-141 is listed at about 2.7 hours; Melanotan II at about 33 hours. That difference is what drives the reported schedules: 1.75 mg as needed, maximum one dose per 24 hours versus Loading 250–500 mcg daily, then weekly maintenance
Route of administration
PT-141 is administered by subcutaneous auto-injector, 45 minutes before activity. Melanotan II is administered by subcutaneous injection.
Legal and regulatory status differs
PT-141: FDA-approved (Vyleesi) for premenopausal HSDD; other uses are off-label. Melanotan II: Not approved anywhere; illegal to sell for human use in the UK, EU and US. This is usually the most practical difference between two compounds, because it determines whether a supply chain is labelled and regulated at all.
Handling and storage
PT-141 is stored room temperature for the approved auto-injector. Melanotan II is stored refrigerated after reconstitution.
What PT-141 and Melanotan II have in common
On the attributes tracked in this database — category, evidence grade, mechanism, half-life, administration, dosing overview, storage and legal status — PT-141 and Melanotan II share no identical values. They are compared here because they come up together in the same searches, not because they overlap.
Each compound in brief
PT-141
Sexual health · Strong evidence
An FDA-approved melanocortin agonist for hypoactive sexual desire disorder that works through the central nervous system rather than the vascular system.
Considerations: Raises blood pressure transiently — avoid with uncontrolled hypertension · Nausea is common at higher doses · Label limits use to eight doses per month
Melanotan II
Skin & hair · Limited evidence
A melanocortin agonist that stimulates tanning and libido — and the peptide most associated with real, documented harms.
Considerations: Case reports link it to changing moles and melanoma diagnoses · Non-selective receptor action means side effects are the rule, not the exception · Bremelanotide (PT-141) is the regulated alternative for sexual-health goals only
Related comparisons and reading
Every figure on this page is reproduced from the compound profiles in this database and reflects published literature and commonly reported protocols. It is educational information, not medical advice, and not a recommendation to use either compound. See the medical disclaimer.