PT-141 vs Melanotan II: Close Cousins, Different Status
App Library Tools Pricing Download
[Peptides · Comparison]

PT-141 vs Melanotan II: how do they differ?

Structure · FDA status · Label and studies

Short answer: PT-141 (bremelanotide) differs from Melanotan II only at its tail end: a free acid instead of an amide.12 Bremelanotide is FDA approved as Vyleesi, a 1.75 mg as-needed injection for premenopausal women with low sexual desire; the label says it is not for men.1 Melanotan II has never been approved, and FDA notes reports of melanoma and other serious events.3

How do PT-141 and Melanotan II compare side by side?

PT-141 from the Vyleesi label and its phase 3 trials; Melanotan II from published studies and FDA records.
PT-141 (bremelanotide, Vyleesi)Melanotan II
StructureAc-Nle-cyclo(Asp-His-D-Phe-Arg-Trp-Lys)-OH: free acid at the end1The same ring of amino acids with an amide (-NH2) at the end2
FDA statusApproved as Vyleesi (initial approval 2019)1Never approved; nominated for compounding, then withdrawn3
Approved usePremenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD); not for men, postmenopausal women or to enhance performance1None
Label or study dosing1.75 mg under the skin at least 45 minutes before sexual activity; no more than 1 dose in 24 hours; more than 8 a month not recommended10.025 mg/kg under the skin in two small erectile dysfunction studies45
Half-lifeAbout 2.7 hours (range 1.9 to 4.0); peak at about 1 hour1No published human figure in the sources we checked
Nausea40% vs 1.3% on placebo in phase 31Common; 4 of 19 injections caused severe nausea in one study5
Skin darkeningFocal hyperpigmentation in 1% with up to 8 doses a month; 38% after 8 daily doses in another study1Tanning was its original purpose2
Blood pressureUp to 6 mmHg systolic and 3 mmHg diastolic, peaking 2 to 4 hours after a dose1Not reported in the abstracts cited here

Reviewed . Half-life figures are shown only where the value Dose Track uses agrees with the cited source.

How close are they chemically?

Very close. Melanotan II is a ring-shaped peptide written Ac-Nle-Asp-His-D-Phe-Arg-Trp-Lys-NH2.2 The Vyleesi label describes bremelanotide as the same ring with a free acid at the end instead of the amide.1 Melanotan II was first studied for tanning, and its early trials found erections as a side effect; bremelanotide was developed for sexual function.24

What do the Vyleesi trials and label show?

Two 24-week phase 3 trials (RECONNECT) enrolled 1,267 premenopausal women with HSDD. Bremelanotide raised desire scores and lowered related distress more than placebo, and nausea, flushing and headache each affected 10% or more.6 In the pooled label data, nausea was 40% vs 1.3%, flushing 20.3% vs 0.3% and headache 11.3% vs 1.9%.1

The label does not allow use with uncontrolled high blood pressure or known heart disease, and says Vyleesi can sharply lower blood levels of naltrexone taken by mouth.1

What is known about Melanotan II?

Human data are small and old: a 3-man pilot study and two crossover studies of 10 men each with erectile dysfunction.245 FDA notes published case reports of melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxidrome and priapism.3 No study has compared the two directly. These are study protocols, not personalized advice; confirm any dosing with your prescriber.

More detail: Vyleesi side effects, the Vyleesi dosing schedule, and the PT-141 (Bremelanotide) and Melanotan II guides.

This page summarizes labels and published studies. It is not personalized medical advice; confirm any dose or change with your prescriber.
Melanotan 1 vs Melanotan 2: how do they differ?FDA-approved implant drug vs unapproved peptide Tadalafil vs sildenafil: how do Cialis and Viagra differ?17.5-hour vs 4-hour half-life Cialis daily vs as needed: how do the two tadalafil schedules differ?2.5 to 5 mg every day vs 10 to 20 mg when needed

Frequently asked questions

Is PT-141 the same as Melanotan II?+
Nearly. Bremelanotide has the same ring of amino acids but ends in a free acid instead of an amide.12
Is PT-141 approved for men?+
No. The Vyleesi label says it is not indicated for men, for postmenopausal women, or to enhance sexual performance.1
How often can Vyleesi be used?+
No more than one dose in 24 hours, and more than 8 doses a month is not recommended, partly because of skin darkening and blood pressure effects.1
Does PT-141 cause tanning like Melanotan II?+
It can cause darkened patches. In phase 3 this was 1% with up to 8 doses a month, but 38% after 8 daily doses in another study.1
Can I track PT-141 or Melanotan II in Dose Track?+
Yes. Both are built in, with reconstitution math and reminders.

Sources

  1. Vyleesi (bremelanotide) injection prescribing information, sections 1, 2, 4, 5, 6.1, 7, 11 and 12.3. DailyMed, version of November 2025.
  2. Dorr RT, et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci. 1996;58:1777-84.
  3. FDA. Certain bulk drug substances for use in compounding that may present significant safety risks (Category 2 and nominated-but-withdrawn lists). Updated April 2026.
  4. Wessells H, et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. J Urol. 1998;160:389-93.
  5. Wessells H, et al. Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunction. Urology. 2000;56:641-6.
  6. Kingsberg SA, et al. Bremelanotide for the treatment of hypoactive sexual desire disorder: two randomized phase 3 trials. Obstet Gynecol. 2019;134:899-908.

All compound comparisons · PT-141 (Bremelanotide) guide · Melanotan II guide · All compound guides · Peptide tracking in Dose Track