An independent peptide reference — no sellers, every claim sourced

PT-141

Also known as Bremelanotide, Vyleesi, PT-141 acetate

Melanocortin receptor agonist, approved in the US for low sexual desire in premenopausal women.

clinically proven Hormonal & sexual approved drug

At a glance

Category
Hormonal & sexual
Status
approved drug
Route
subcutaneous (abdomen or thigh)
Half-life
about 2.7 hours, range 1.9-4.0 hours (human, subcutaneous) 4
Onset
about 45 minutes to several hours after injection
Molecular weight
1025.2 g/mol as the free base 4
Sequence
Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH

Approved by the FDA in June 2019 as Vyleesi (bremelanotide injection, 1.75 mg) for acquired, generalised hypoactive sexual desire disorder (HSDD) in premenopausal women 4. Not centrally registered in the EU; the European marketing authorisation application was not pursued. Use in men and in postmenopausal women is off-label and not approved.

Doping status: Not listed by WADA

Checked against the WADA 2026 Prohibited List. For a specific product and country, Global DRO is the lookup athletes are expected to use — the List names substances, not brand names.

Mechanism of action

Bremelanotide is a non-selective agonist of melanocortin receptors, with the highest potency at MC1R and MC4R and weaker activity at MC3R, MC5R and MC2R. At therapeutic doses, binding to MC1R and MC4R is considered clinically relevant.

Unlike PDE5 inhibitors it does not act on vasodilation in genital tissue, but centrally: activation of MC4R in hypothalamic nuclei influences dopaminergic pathways involved in sexual motivation. The exact route by which this leads to greater sexual desire has not been fully elucidated in humans.

MC1R activation explains the additional, dose-dependent skin pigmentation that can occur with repeated use.

What the research shows

For the approved indication the evidence is strong by the standards of this field: two identical randomised, double-blind, placebo-controlled phase 3 trials with more than 1,200 participants combined 2. The effect is statistically significant but modest in absolute terms, and almost half of users experienced nausea. For applications other than HSDD in premenopausal women the evidence is far thinner.

Research in humans

The RECONNECT trials (phase 3, published in Obstetrics & Gynecology, 2019) showed significant improvement on the validated scales for sexual desire (FSFI-D) and associated distress (FSDS-DAO question 13) compared with placebo 2. A subsequent 52-week open-label extension study assessed long-term safety. Earlier phase 2 studies in men with erectile dysfunction showed an erectile response, but this programme was not pursued; intranasal administration was discontinued because of a rise in blood pressure.

Animal and lab research

Animal models (rats) show an increase in erections and in sexually motivated behaviour after melanocortin agonism, mediated via MC4R in the hypothalamus. These models support the mechanism, but translate poorly to the subjective outcome of 'desire' in humans.

Caveats. The absolute effect size is small: the difference from placebo on the desire score was about 0.3 points on a scale from 1.2 to 6.0 2. Studies were funded by the manufacturer. Dropout due to side effects was considerable (about 18% in the phase 3 trials). There is no evidence of efficacy in postmenopausal women or in men with reduced desire.

What it is used for

  • Acquired, generalised hypoactive sexual desire disorder (HSDD) in premenopausal women — the only approved indication 4
  • Off-label use in men for libido and erectile function, without registration and without phase 3 support
  • Off-label use for SSRI-induced sexual dysfunction — studied but not registered

Dosing

Dose
1.75 mg per administration (approved dose)
Frequency
as needed, at most 1 dose per 24 hours; more than 8 doses per month is not recommended
Route
subcutaneous in the abdomen or thigh, with a prefilled autoinjector
Duration
as-needed use; discontinue after 8 weeks if no improvement occurs
  • Administer at least 45 minutes before anticipated sexual activity, subcutaneously into the abdomen or thigh; no more than one dose in 24 hours and no more than 8 doses per month 4.
  • The doses above come from the official FDA product information for Vyleesi, not from user protocols.
  • Loose powder vials with doses of 0.5-2 mg circulate on the grey market. Those products are not checked for purity or content; the approved autoinjector is.
  • A transient rise of about 6 mmHg systolic and 3 mmHg diastolic peaks 2-4 hours after the dose, with a fall in heart rate of up to 5 beats per minute, usually resolving within 12 hours 4.

These figures describe what the literature and published protocols report. They are not advice and not a dosing instruction.

Protocols

Vyleesi (hypoactive sexual desire disorder in premenopausal women)

approved product information

Source: VYLEESI (bremelanotide injection) prescribing information, FDA

Per occasion1.75 mg subcutaneously in the abdomen or thigh by autoinjector, at least 45 minutes before anticipated sexual activity
Maximum frequencyone dose per 24 hours, and no more than 8 doses per month
Stopping rulediscontinue after 8 weeks if there has been no improvement

An on-demand dose rather than a daily one, and the eight-doses-a-month ceiling is part of the licensed schedule, not a suggestion. Nausea is the commonest reason people stop, and each dose is followed by a transient rise in blood pressure of roughly 6 mmHg systolic with a compensatory fall in heart rate.

Grey-market on-demand use (user-reported)

user protocol — not validated

Source: The pattern repeated across men's-health, libido and peptide forums together with grey-market vendor labelling of loose powder

This is not a validated schedule. It is a pattern that circulates among users and sellers, reproduced because it is what people actually follow — not because it has been tested. No trial established these doses, this interval or this duration, and nobody is checking what is in the vial. Treat every number below as an assertion, not a finding.

Per occasion, most commonly reported1-2 mg subcutaneously, 45 minutes to a few hours before anticipated activity
Reported lower end0.25-0.5 mg, described by users microdosing specifically to limit nausea
Reported frequencyon demand, but often several times a week — commonly exceeding the label's ceiling of 8 doses per month

This is the clearest label-versus-practice gap in the melanocortin group. The label directs a single fixed 1.75 mg dose from a purity-controlled autoinjector, at most 8 times a month, in premenopausal women with HSDD; users report reconstituting loose 'PT-141' powder and self-injecting it — men as often as women, for erectile function and libido as well as desire — at doses spanning roughly 0.25 to 2 mg and at frequencies that routinely pass the monthly ceiling. None of these figures has a published basis, the powder is not tested for identity or purity, and reports disagree by close to tenfold on what a 'dose' is. The unflattering reports track the label: nausea is the commonest complaint (the trials saw it in about 40%), with flushing, headache and a transient blood-pressure rise, and repeated use is associated with focal darkening of the skin through the drug's MC1R activity. 'No effect' reports also circulate. That users report few serious problems is not evidence of safety: this is an unmonitored population injecting an unverified product.

Schedules are reproduced as their source states them. Units, IU and milligrams explains why the figures are not interchangeable between products.

Reconstitution

Vial sizes
prefilled autoinjector 1.75 mg/0.3 ml (Vyleesi), 10 mg powder (grey market)
Solvent
not applicable for Vyleesi (ready-to-use solution); powder products are usually dissolved in bacteriostatic water
Storage
Store Vyleesi at 20-25 °C, do not freeze, protect from light. Reconstituted powder: 2-8 °C, usually stable for a few weeks; unreconstituted powder in the freezer.

Worked example

A 10 mg powder vial with 2 ml bacteriostatic water gives 5 mg/ml; 1.75 mg then corresponds to 0.35 ml, that is 35 units on a U100 insulin syringe.

Do not shake. The worked examples for powder vials are descriptive; they are not a recommendation to use an unregulated product.

Work it out for PT-141

Safety

Side effects

  • Nausea — the most common side effect, reported by about 40% of users versus 1% on placebo; about 13% used antiemetics 4
  • Flushing (about 20.3%) 4
  • Injection site reactions (about 13.2%) 4
  • Headache (about 11.3%) 4
  • Vomiting (about 4.8%) 4, coughing, fatigue, dizziness
  • Focal hyperpigmentation of the face, gingiva and breasts, about 1% in patients receiving up to 8 doses a month, and not confirmed to resolve in all patients after stopping — more common with daily dosing and with darker skin 4
  • Transient rise in blood pressure and reduction in heart rate in the hours after administration

Do not use if

  • Uncontrolled hypertension 4
  • Known cardiovascular disease 4
  • Pregnancy — discontinue if pregnancy is suspected; there are insufficient data on safety for the foetus
  • Postmenopausal women and men: not approved, efficacy not demonstrated
  • Reduced sexual desire caused by a relationship problem, another condition or a medicine: not an indication

Interactions

Slows gastric emptying and can therefore reduce the absorption of orally administered drugs taken at the same time; this is relevant for agents with a narrow therapeutic index, and the label documents reduced indometacin absorption 4. The product information advises against combining it with oral naltrexone-containing medicines, because systemic exposure to naltrexone falls significantly 4. Combination with alcohol has not been systematically studied.

Common questions

What is PT-141 (Vyleesi)?
PT-141, or bremelanotide, is a melanocortin-receptor agonist approved in the US for low sexual desire (HSDD) in premenopausal women. Unlike the erectile-dysfunction pills, it acts on the brain’s melanocortin pathway rather than on blood flow.
Does PT-141 work for men or for erectile dysfunction?
Its approval is for low desire in women; use in men, or specifically for erectile dysfunction, is off-label and less well supported. Nothing here is medical advice.
What are the side effects of PT-141?
The common ones are nausea, flushing and a transient rise in blood pressure; it can also darken the skin. See the safety section above.
What is the difference between PT-141 and melanotan?
Both hit melanocortin receptors, but PT-141 is an approved desire drug and melanotan II is an unapproved tanning peptide with safety concerns. See PT-141 vs melanotan II.

Sources