Melanocortin-receptor agonists for desire, arousal, and sexual response. PT-141 and Melanotan II — the two clinically distinct options on the market.
FDA-approved (Vyleesi) melanocortin libido peptide. 99.5% purity, lab-tested. View product →
by Apex Research · ★ 4.9 (1,624 reviews)A melanocortin-receptor agonist (MC1R/MC4R) that acts centrally on sexual desire pathways — distinct from PDE5 inhibitors which act peripherally on blood flow. FDA-approved for hypoactive sexual desire disorder in women under the brand name Vyleesi. Effective in both sexes.
Original parent compound that PT-141 was derived from. Synthetic alpha-MSH analog with documented libido and erection effects in addition to its primary tanning use. Side-effect profile heavier than PT-141 (nausea, flushing, mole darkening). Cross-shops with skin.
Intranasal formulation of PT-141 for buyers avoiding injection. Slightly slower onset than subcutaneous but more discreet — easier to dose 45 minutes before intimacy without ritual interruption. The most popular SKU among first-time buyers in this category.
Smaller trial-size vial of PT-141 for buyers wanting to test response before committing to a 10mg vial. Typical individual dose is 1–2 mg; a 5mg vial yields roughly 3–4 administrations. Most users dial in a sub-nausea-threshold personal dose within the trial.
Standard 5mg vial — typical libido protocol is 250–500 mcg as needed (lower than tanning loading dose). Reconstitute with 2 mL bacteriostatic water for easy fractional dosing. Cross-shops with skin.
The libido category is small because the underlying mechanism is narrow. Both peptides on this page act on melanocortin receptors (MC1R and MC4R), which are upstream of central nervous system pathways governing sexual desire. This is mechanistically different from PDE5 inhibitors (Viagra, Cialis), which act peripherally on blood-flow regulation. Buyers who haven't responded to PDE5 inhibitors often respond to PT-141, and vice versa — the two classes are complementary rather than competing.
PT-141 was developed specifically for sexual dysfunction and is FDA-approved under the brand name Vyleesi for hypoactive sexual desire disorder in premenopausal women. Studies in men and women document increases in desire, arousal, and satisfaction. Acts on MC4R in the hypothalamus rather than peripheral blood-flow pathways. Typical administration is 1–2 mg subcutaneous (or intranasal) 45 minutes before activity. Effect duration is 6–8 hours; some residual effect for 24+ hours after a single dose.
Melanotan II is the original synthetic alpha-MSH analog that PT-141 was derived from. It hits both MC1R (driving melanogenesis — the tanning effect) and MC4R (driving libido). The dual mechanism makes it appealing to buyers wanting both effects, but the broader receptor activity also produces a heavier side-effect profile: nausea (especially first dose), facial flushing, occasional mole darkening, and (rarely) priapism in men. Start at 250 mcg and titrate up.
Most buyers in this category land on PT-141 after one of three triggers: PDE5 inhibitors stopped working, desire and arousal feel mechanically separate, or a partner-aligned approach to sexual health is wanted (since PT-141 works for both sexes). Melanotan II users typically came in for the tanning effect and discovered the libido effect as a bonus, or actively want the broader receptor activity for reasons their healthcare provider supports.
PT-141: nausea is the most common side effect (typically dose-dependent — titrate down if it occurs), facial flushing, mild blood-pressure changes. Avoid in uncontrolled hypertension. Melanotan II: same effects but stronger, plus mole darkening, occasional priapism in men, and the tanning effect (welcome or unwelcome depending on goals). Neither peptide should be combined with PDE5 inhibitors without medical guidance. None are FDA-approved for off-label libido enhancement in men. Always consult a licensed healthcare provider, especially with cardiovascular conditions.
| Buyer profile | Start with | Why |
|---|---|---|
| First-time libido peptide user | PT-141 trial 5mg | Cleanest profile, FDA-approved class |
| Avoid injection | PT-141 nasal spray | Same molecule, no needles |
| Want libido + tanning | Melanotan II | Dual mechanism |
| PDE5 inhibitors stopped working | PT-141 | Different mechanism (central vs peripheral) |
| Long-protocol user | PT-141 10mg vial | Better cost per dose |
Want the full deep-dive? Read our complete guide to peptides for libido with dosing protocols and side-effect management.
Viagra (sildenafil) is a PDE5 inhibitor — it works peripherally on blood-vessel dilation. PT-141 is a melanocortin-receptor agonist — it works centrally on the sexual-desire pathway in the hypothalamus. Different mechanisms, often complementary. Combining them is not recommended without medical guidance because of additive blood-pressure effects.
Nausea is the most common side effect at the FDA-approved dose (1.75 mg). Most buyers find a sub-nausea threshold around 0.75–1 mg that retains most of the libido effect. Titrate up from a low starting dose to find your personal threshold.
Subcutaneous PT-141: effect begins around 30–45 minutes, peaks at 2–3 hours. Nasal: effect begins around 15–30 minutes, slightly less peak intensity but more convenient dosing. Plan administration around the window of intended activity.
Yes — PT-141 is FDA-approved specifically for women (Vyleesi) and is used off-label by men. Many couples coordinate dosing. Each partner should establish their own response and dose before any combined protocol.