PT-141

Bremelanotide, Vyleesi, PT-141, the "arousal peptide"

Checked Oct 28, 2026

The short answer

Proven in humans for erections in men (off label)

Approved?: Approved for: acquired, generalized hypoactive sexual desire disorder in premenopausal women (FDA, 2019, Vyleesi).
Safety: C, thinly characterized: Nausea affected 40% of treated women in the trials, and every dose briefly raises blood pressure, so it is not for people with uncontrolled high blood pressure or heart disease.

The full answer: what it is for, the dose, the units

What people take it for: People take it before sex to raise desire and arousal. It acts on melanocortin receptors in the brain rather than on blood flow, and it is FDA-approved only for low desire in premenopausal women.

Does it work for erections in men (off label)? A, proven in humans. Result: mixed.

Grade A for erections in men, the off-label use it is most often bought for, result mixed: two early trials in 2004 raised lab-measured erections and a larger 2008 trial is under a journal expression of concern. Whether it raises desire in men was never measured, which is grade D. For the approved use in women it is also grade A, with a small average gain over placebo.

Approved for: acquired, generalized hypoactive sexual desire disorder in premenopausal women (FDA, 2019, Vyleesi). That does not carry over to men, to postmenopausal women, or to improving sexual performance; the label says it is not indicated for those. VYLEESI (bremelanotide) prescribing information, DailyMed

Safety: C, thinly characterized. Nausea affected 40% of treated women in the trials, and every dose briefly raises blood pressure, so it is not for people with uncontrolled high blood pressure or heart disease.

Do not use if: Contraindicated in uncontrolled hypertension or known cardiovascular disease, and not recommended for those at high CV risk.

Could it be placebo? In the two women's trials the injection beat placebo on the desire score by 0.35 points on average, and in men the randomized trials measured lab erections rather than desire, so a placebo effect on desire cannot be ruled out.

The dose people use, and the units to draw

The approved dose is 1.75 mg under the skin at least 45 minutes before sex, no more than once in 24 hours and no more than 8 times a month. The men's trials gave 4 mg and 6 mg subcutaneously, and no named source gives an off-label dose.

Source	Dose	How often and how	Who it was for	Link
VYLEESI label (FDA-approved product)	1.75 mgUse this dose	Subcutaneous in the abdomen or thigh, at least 45 minutes before sexual activity; no more than one dose in 24 hours and no more than 8 doses per month	Premenopausal women with acquired, generalized hypoactive sexual desire disorder	Section 2 Dosage and Administration
Kingsberg et al. 2019 (RECONNECT, two phase 3 trials)	1.75 mgUse this dose	Subcutaneous as needed for 24 weeks, versus placebo	1,267 premenopausal women with hypoactive sexual desire disorder randomized (1,247 in the safety group)	abstract
Rosen et al. 2004 (subcutaneous, men)	4 mg and 6 mg in men with erectile dysfunction; 0.3 to 10 mg single doses in healthy men	Subcutaneous; patients crossed over between placebo, 4 mg and 6 mg; erection measured by RigiScan with visual stimulation	Healthy men and men whose erections were inadequate on 100 mg Viagra	abstract
Diamond et al. 2004 (intranasal, men)	Erectile response significant versus placebo at doses above 7 mg; full range not in the abstract	Intranasal, double-blind placebo-controlled; first erections at about 30 minutes	Healthy men and men with mild-to-moderate erectile dysfunction who responded to Viagra	abstract
Huberman Lab, Apr 1, 2024 (Andrew Huberman)	No dose stated	Says PT-141 (Vyleesi) is FDA-approved for premenopausal women with low desire and that men also take it off label; names nausea, flushing and blood-pressure rise as side effects	General discussion of melanocortin peptides for vitality	01:16:11 (auto-transcript at podscripts.co, verify by ear)

From 1.75 mg subcutaneously (label and the women's trials) up to 6 mg subcutaneously (Rosen 2004, men with inadequate response to Viagra).

No named non-seller source gives an off-label dose for men or postmenopausal women; the site's earlier off-label range and starting dose had no named source. Dr. Abud Bakri did not discuss PT-141 in the Jun 2026 Huberman Lab episode, and Examine.com could not be opened (rate limited). The 2008 intranasal trial of 342 men (J Urol) is under a journal expression of concern and is not used as a dose source.

Reported by the named source, never prescribed by us.

How many units do I draw?

On a U-100 insulin syringe, units = 100 x dose (mg) / (vial mg / water mL). Enter your vial size, the water you add and the dose in the calculator and it does the arithmetic. Open the dose calculator

Why it might work

Subcutaneous injection (~45 min before activity)
Bremelanotide (a synthetic cyclic hept
Non-selective melanocortin receptor binding (MC1R, MC3R, MC4R, MC5R)
The peptide binds melanocortin recepto
MC4R activation in hypothalamic desire circuits
MC4R stimulation on neurons in the med
Transient blood-pressure and heart-rate changes
Melanocortin receptor activation also
Subjective desire and arousal (demonstrated in women; assumed/observational in men)
Two Phase 3 RCTs (RECONNECT

Assumed pathway, not shown in people.

Bremelanotide is a synthetic cyclic heptapeptide and a non-selective melanocortin receptor agonist (MC1R, MC3R, MC4R, MC5R; not MC2R), acting primarily via MC3R/MC4R. The proposed central mechanism: activation of MC4R on neurons in the hypothalamus (medial preoptic area) modulates downstream dopamine signaling in brain reward/motivation circuits, increasing sexual desire and arousal. This is a CNS desire pathway, distinct from the vascular/erectile mechanism of PDE5 inhibitors. Because it is an approved drug, the mechanism is reasonably established rather than purely assumed, though the precise neurocircuitry linking MC4R to desire is still incompletely mapped. Off-target MC1R activation drives the pigmentation and tanning effects.

The trials, claim by claim

The result tag for men reads 'mixed': the early trials raised lab erections, but desire was not measured and the larger 2008 trial is under a journal expression of concern.

Bremelanotide is FDA-approved (Vyleesi, June 2019) for acquired, generalized HSDD in premenopausal women - the first melanocortin agonist approved for a sexual-desire indication (afamelanotide, an MC1R agonist, was FDA-approved earlier, in 2019, for erythropoietic protoporphyria).

Result: worked

FDA approval supported by two identical Phase 3 randomized, double-blind, placebo-controlled trials (RECONNECT, ~1,247 women).

DailyMed. VYLEESI (bremelanotide) label (Cosette, current)

Two Phase 3 RCTs showed statistically significant improvements in the desire and distress endpoints (FSFI-desire and FSDS-DAO item 13) versus placebo, with a 52-week open-label extension showing no new safety signals.

Result: worked

Published Phase 3 trials and long-term open-label extension in peer-reviewed literature.

Kingsberg et al. 2019, Bremelanotide for HSDD: two randomized phase 3 trials (Obstet Gynecol)

Effect size in the trials was statistically significant but modest, and the placebo response was substantial, a recurring critique of HSDD endpoints, which are subjective self-report scales.

Result: worked

Reported trial deltas on subjective questionnaire endpoints; large placebo arm response is documented in the Phase 3 data.

Spielmans and Ellefson 2024, Small effects, questionable outcomes (J Sex Res); PMID 36809187

Use in men is off-label. The only randomized male trial (intranasal, 2008, 342 men) with a clinical-response outcome is under a journal expression of concern; two earlier 2004 randomized early-phase trials (subcutaneous, PMID 14999221, and intranasal, PMID 14963471) measured lab erections, the program was halted in 2007 over blood pressure, and recent data are small case series.

Result: mixed

Original male ED program discontinued over blood-pressure concerns; subsequent male data is limited observational/case-series.

Safarinejad and Hosseini 2008, J Urol (under Expression of Concern, PMID 36626345)

A 2026 meta-analysis found bremelanotide improved total FSFI and its desire and arousal subscales in women with desire, arousal or orgasm dysfunction.

Result: worked

Systematic review and meta-analysis including RCTs; effect sizes not read from the abstract; sits beside an independent re-analysis calling the RECONNECT benefit statistically modest on weakly validated outcomes.

J Minim Invasive Gynecol 2026 (PMID 40543759)

Low-dose bremelanotide added to tirzepatide produced more weight loss than placebo in an 8-week phase 2 study.

Result: worked

Company press release only, not peer reviewed, 96 randomized, 8 weeks, low doses; registry NCT06565611.

Palatin press release, March 31, 2025

Status

The intranasal formulation was abandoned because the FDA halted Phase 2 trials in 2007 over clinically meaningful blood-pressure increases.

Documented regulatory history of the Palatin intranasal program.

ClinicalTrials.gov NCT02333071 and NCT02338960 (RECONNECT)

Risks and the label warnings

Adverse events

Nausea is the dominant adverse effect, about 40% of treated women in Phase 3 trials (vomiting about 5%). About 13% needed anti-nausea medication and 8% left the trials because of it. Flushing (~20%), injection-site reactions (~13%), and headache (~11%) are also common.

Contraindications

Contraindicated in uncontrolled hypertension or known cardiovascular disease, and not recommended for those at high CV risk. Each dose causes a transient BP rise (label: max ~6 mmHg systolic / 3 mmHg diastolic) and HR drop, usually resolving within 12 hours. Do not exceed one dose per 24 hours or 8 doses per month. The label ties the monthly limit to focal hyperpigmentation (38% of people in a daily-dosing study over 8 days); blood pressure and heart rate effects did not add up across repeat daily doses. May slow gastric emptying and reduce absorption of oral drugs (e.g., a documented interaction reducing naltrexone exposure).

Theoretical concerns

Melanocortin activation (MC1R) drives melanin production, so the same pathway that may cause incidental tanning also causes focal hyperpigmentation of the face, gums, and breasts, higher risk with darker skin and with frequent dosing, and resolution was not confirmed in all patients. The MC4R mechanism also produces transient blood-pressure elevation and heart-rate reduction with every dose.

What nobody knows yet

Long-term safety beyond ~1 year is not characterized. Off-label use in men and postmenopausal women lacks RCT safety data, and gray-market PT-141 (research-chemical vials, not the regulated Vyleesi autoinjector) carries unknown purity, dose accuracy, and sterility, none of the label's safety dataset applies to an unregulated vial. Cumulative cardiovascular risk from repeated on-demand dosing in people the label would have excluded is untested.

What else could explain the result

Off-label users frequently stack PT-141 with PDE5 inhibitors (sildenafil/tadalafil), testosterone/TRT, or other libido agents, any of which can independently change arousal or erectile function and muddy attribution. Expectancy is a major confounder for a subjective sexual outcome taken right before planned intimacy. An erection within hours of dosing (commonly reported) is not the same endpoint as increased desire, and the two are often conflated in anecdotes.

Is the vial what it says?

Profile cross-checked against the FDA-approved VYLEESI label (DailyMed), the Wikipedia development-history summary (intranasal halt 2007, June 2019 approval, 2.7 h half-life, MC3/MC4 mechanism), and PubMed records of the Phase 3 RECONNECT trials and long-term extension. Adverse-event percentages and the daily-dosing hyperpigmentation figure (38% over 8 days) are taken directly from the label.

Half-life and storage

Half-life: Elimination half-life approximately 2.7 hours (range ~1.9-4.0 hours); plasma levels decline biphasically after peak. Short half-life is consistent with its on-demand, pre-activity dosing.

Once mixed: The regulated product (Vyleesi) ships as a pre-filled single-use autoinjector requiring no reconstitution, eliminating handling error. Gray-market lyophilized PT-141 must be reconstituted with bacteriostatic water, kept refrigerated once mixed, protected from light and repeated freeze-thaw, and used within a limited window; peptide degradation from poor handling reduces potency unpredictably. Reconstitution sensitivity is therefore a gray-market-only concern, but a real one.

What I noticed, and what people report

What people report

Volume of reports: moderate. A real body of reports, fairly consistent.

High discussion volume across men's-health and TRT forums (ExcelMale and similar) and a large vendor/affiliate footprint, since it is one of the most marketed gray-market peptides. Volume is inflated by commercial sources, which should be discounted.

Genuinely mixed. Responders describe a noticeable rise in arousal/desire and spontaneous erections within hours; a substantial minority report no libido effect at all, or get the side effects (cold/achy feeling, low mood for several hours, nausea) without the benefit. The split between strong responders and non-responders is one of the most consistent themes, which argues for high inter-individual variability.

Moderate. The for-women indication is anchored by real RCTs and an FDA label, which is far stronger than the typical peptide on this site. But the dominant off-label narrative (men, on-demand) is carried by anecdote plus small observational series, and much of the online enthusiasm originates from vendors who sell it, so credibility on the popular use case is capped.

Anecdote, not proof: many users describe a real, noticeable jump in arousal and 'wanting to' within an hour or so of dosing, often framed as desire/headspace rather than just a mechanical erection.
A recurring counter-theme is non-response: a meaningful share report the side effects (flushing, nausea, feeling cold/achy or low for several hours) with little or no change in libido, strong responders and non-responders both show up consistently.
Nausea is the most-cited downside; some users report it fades with repeated use, while others find it bad enough to stop.
Community sentiment is cautious: experienced users flag the blood-pressure and skin-darkening warnings.

Reports are anecdote, not proof.

Can you tell if it is working?

Not trackable

No objective non-blood tracker exists, PT-141's only efficacy endpoint is subjective sexual desire/arousal, so you verify it by how you feel, not by any scan, wearable, or lab.

Bloodwork

No blood proxy

Nothing on a routine panel confirms this one. Anyone who says otherwise is guessing.

PT-141 (bremelanotide) is a centrally-acting melanocortin receptor agonist (primarily MC4R on hypothalamic neurons). Its therapeutic effect is a subjective, CNS-mediated increase in sexual desire/arousal. It does not act on an endocrine or metabolic axis that releases a measurable circulating analyte, so nothing about its efficacy appears in routine bloodwork.

Read this before you spend on labs

Routine bloodwork cannot confirm PT-141 is working. Its action is neurobehavioral: it drives sexual desire/arousal via central melanocortin (MC4R) signaling, and the only human-validated endpoints are subjective self-reported desire and distress scales (the FDA RECONNECT phase 3 trials). There is no orderable lab that reflects this efficacy. The one objective, measurable effect on the FDA label is a transient rise in blood pressure (with a small reflex drop in heart rate) after dosing, but that is a vital-sign safety/pharmacodynamic signal, not bloodwork, and it indicates only drug exposure, not therapeutic benefit. Efficacy here can only be judged by the user's own experience, which makes this compound high placebo-risk.

Bottom line

PT-141 (bremelanotide) works centrally at MC3R/MC4R to raise sexual desire, and its efficacy in humans is measured only by self-reported scales (FSFI desire domain, FSDS-DAO distress, desire diaries), there is no validated objective proxy for libido. No non-blood modality applies: urine, stool, CGM, VO2max, DEXA, body composition, and genetics are all irrelevant to its mechanism, and sleep/HRV wearables track nothing it acts on. The one objective physical sign, a transient ~6 mmHg systolic BP rise (with a small heart-rate drop) on a cuff, reflects drug exposure and MC4R activity, NOT whether desire improved, so it is a safety/pharmacodynamic signal and is deliberately excluded as an efficacy channel. Placebo risk is high (dosing right before planned intimacy under peak expectancy), which is exactly why an objective readout would help and exactly why none exists. Honest verdict: track this with a simple pre/post desire-and-distress diary, not with any device or panel.

Logging baseline vs retest is the whole game. The Truth Tracker is our free log for bloodwork, DEXA, genetics, and wearable data, bring your own numbers.

How to track it

History

First documented human use: Human trials date to the early 2000s, when Palatin Technologies tested an intranasal formulation in both male erectile dysfunction and female sexual dysfunction. Those Phase 2 programs were halted by the FDA in 2007 over blood-pressure increases. The reformulated subcutaneous drug (Vyleesi) was FDA-approved on 21 June 2019 for acquired, generalized HSDD in premenopausal women, making it one of the very few peptides on this site backed by completed, registered human RCTs.

Early 2000sPalatin Technologies tests intranasal bremelanotide (a derivative of melanotan II) in Phase 2 trials for male erectile dysfunction and female sexual dysfunction.
2007FDA halts the intranasal Phase 2 program over increased blood pressure in subjects; the intranasal route is abandoned in 2008.
Late 2014Phase 3 trials of reformulated subcutaneous bremelanotide for HSDD begin (RECONNECT).
2017Palatin licenses U.S. development/commercialization rights to AMAG Pharmaceuticals; Phase 3 RECONNECT trials complete.
21 June 2019FDA approves Vyleesi (bremelanotide) for acquired, generalized HSDD in premenopausal women.

All sources

DailyMed. VYLEESI (bremelanotide injection) label(Authoritative FDA label: indication, dosing, contraindications, BP/HR and hyperpigmentation warnings, adverse-event rates.)
Kingsberg et al. 2019, Bremelanotide for HSDD: two randomized phase 3 trials (Obstet Gynecol)(The two RECONNECT Phase 3 RCTs supporting approval.)
PubMed. Long-term safety and efficacy of bremelanotide for HSDD (Obstet Gynecol 2019)(52-week open-label extension; no new safety signals.)
Safarinejad and Hosseini 2008, J Urol (under Expression of Concern, PMID 36626345)(The one randomized male trial (intranasal ED program); carries a journal expression of concern. Later male data are small observational series (off-label).)
ClinicalTrials.gov NCT02333071 and NCT02338960 (RECONNECT)(Registered trial record incl. the Phase 3 HSDD study (NCT02333071).)
VYLEESI (bremelanotide) prescribing information, Indications and Usage and Dosage and Administration, DailyMed(dose table)
Kingsberg SA et al. Obstet Gynecol 2019 (PMID 31599840)(dose table)
Rosen RC, Diamond LE, Earle DC, Shadiack AM, Molinoff PB. Int J Impot Res 2004;16(2):135-42 (PMID 14999221)(dose table)
Diamond LE, Earle DC, Rosen RC, Willett MS, Molinoff PB. Int J Impot Res 2004;16(1):51-9 (PMID 14963471)(dose table)
Huberman Lab, 'Benefits & Risks of Peptide Therapeutics for Physical & Mental Health', Apr 1, 2024, chapter 01:12:09, about 01:16:11 to 01:17:18(dose table)

Not medical advice. Grades reflect the evidence as of the date above and will change as data arrives. Reports from users are anecdote, not proof. Talk to a licensed clinician before you act on anything here.