Reader’s guide · First edition · September 2026 · Revised September 23, 2026
PT-141
A guide to bremelanotide: an approved drug for women's sexual desire, sold by the vial to men, with a modest effect, a lot of nausea, and a blood-pressure warning on its label
PT-141 is the research-market name for bremelanotide, a peptide that works on the brain's arousal circuits rather than on blood flow. It began life as a tanning compound's side effect, was developed for two decades as a sexual-function drug for both sexes, and was approved in 2019 as Vyleesi for low sexual desire in premenopausal women. Almost everyone buying it by the vial today is a man, using it for erections and libido, which is the use its developer dropped as a stand-alone drug; a combination with a PDE5 inhibitor was announced in 2024 and has reported nothing since. This guide covers what it is, what the trials in women and men showed, how it is dosed on the label and as sold, the nausea and blood-pressure problems that shaped its history, and why the prescription is lawful when the vial is not.
Who this is for
Written for adults who are using, or being offered, PT-141 for sexual desire or erectile function. It summarizes the prescribing information, the published trials, and the regulatory position as of the edition date. It is not medical advice.
In the 1990s, volunteers testing the tanning peptide Melanotan II reported an unexpected side effect: spontaneous erections. The same University of Arizona group followed the observation, and bremelanotide is the result, a seven-amino-acid ring like Melanotan II but with its receptor activity tilted toward the brain's melanocortin-4 receptor, which sits in the circuits that govern sexual motivation, and away from the pigment receptor. It does not act on the penis or the pelvic blood vessels the way sildenafil does. It acts on wanting.
- Class
- Melanocortin receptor agonist, mainly at the MC4 receptor; a metabolite of Melanotan II
- Brand
- Vyleesi, approved June 2019: a 1.75 mg single-dose autoinjector, by prescription, in the United States only
- Approved for
- Hypoactive sexual desire disorder in premenopausal women, meaning distressing low desire not explained by another condition, a relationship problem, or a medicine. Nothing else.
- Forms in use
- The autoinjector by prescription; compounded vials and nasal sprays from telehealth clinics, mostly to men; research-chemical 10 mg vials, which are unapproved drugs
- Anti-doping
- Not on the WADA Prohibited List
Approved for her, sold to him
The label is for premenopausal women with a diagnosis. The market is men who want firmer erections or more desire. The men's trials exist, and they are in this guide, but they stopped in 2008 over blood pressure and never produced a label. A man buying PT-141 is using a women's drug off-label, from a vial, for a purpose its developer gave up on.
Two identical Phase 3 trials, together called RECONNECT, randomized about 1,200 premenopausal women with hypoactive sexual desire disorder to bremelanotide 1.75 mg or placebo, used as needed before sexual activity for 24 weeks. The drug won on both primary endpoints, and the size of the win is the whole story.
Improvement in the desire score (on a scale from 1.2 to 6) over placebo, across both trials; statistically significant, clinically modest
Reduction in distress about low desire (scale 0 to 4) over placebo
Share of treated women who had nausea; 13% needed an anti-nausea drug and 8% quit the trial because of it
Developed patches of darkened skin on the face, gums, or breasts, more often with more than eight doses a month
| Question | Answer from the prescribing information |
|---|---|
| Does it increase desire? | Yes, by a small amount on average, in women with the diagnosis, versus placebo |
| Does it improve sexual events or satisfaction? | The number of satisfying sexual events did not differ from placebo; the approval rests on desire and distress scores |
| Who should not use it? | Anyone with uncontrolled high blood pressure or known cardiovascular disease |
| Why the monthly limit? | Blood pressure rises transiently after each dose; nausea and skin darkening rise with more frequent use |
What this supports
That bremelanotide does something real to sexual desire through the brain, that the effect is modest, and that the price is nausea in nearly half of users. It is an approved drug with a small effect and a clear label. Everything sold under the name PT-141 borrows that approval for other people and other purposes.
Bremelanotide was tested in men first, as a nasal spray for erectile dysfunction, and the results were real: erections on a laboratory measure at doses above about 7 mg, and in men who did not respond to sildenafil, a response rate better than placebo. The program ended when the FDA put the nasal trials on hold in 2007 over rises in blood pressure. The developer switched to injection and to women, and the men's indication was never revived.
| Year | Study | Result | What it supports |
|---|---|---|---|
| 2004 | Intranasal PT-141 up to 20 mg in 32 healthy men and men with mild to moderate erectile dysfunction, placebo-controlled | Measurable erections at doses above 7 mg, beginning about 30 minutes after dosing | The mechanism works in men |
| 2004 | Subcutaneous PT-141, 0.3 to 10 mg, crossover in 25 men with erectile dysfunction who responded poorly to sildenafil | Erections adequate for intercourse at the higher doses | The injected route works too, at doses far above the women's label |
| 2008 | Intranasal 10 mg versus placebo in 342 men who had failed sildenafil, on demand | More successful intercourse attempts than placebo; nausea and flushing common | The largest men's trial; also the last |
| 2007 onward | Nasal program placed on clinical hold by FDA for blood-pressure increases | Development in men stopped | Why there is no men's label |
The women's approved dose is 1.75 mg. The men's trials that showed an effect used 7 to 10 mg nasally or several milligrams by injection. The research-market men's dose of 1 to 2 mg sits between the two, and no trial tested it.
The blood-pressure problem did not go away; it was designed around
The injected form causes a smaller, briefer rise in blood pressure than the nasal spray did, which is why the women's product carries a monthly cap and a contraindication rather than a hold. A man taking larger or more frequent doses from a vial is recreating the conditions that stopped the men's program.
| Form | Instruction | What is known |
|---|---|---|
| Vyleesi (label) | 1.75 mg under the skin of the abdomen or thigh, at least 45 minutes before anticipated sexual activity; no more than one dose in 24 hours and no more than eight in a month | The approved regimen, in women |
| Compounded or research vial, men | 1 to 2 mg under the skin, one to four hours before; some use 0.5 mg to limit nausea | No trial at this dose in men; the effect in men was shown at higher doses |
| Nasal spray, clinic | Metered doses of a compounded spray | The route FDA halted in 2007; spray strengths from compounders vary |
| Stacked with sildenafil or tadalafil | Both taken together | One small crossover in sildenafil non-responders; both drugs move blood pressure, in opposite directions and at different times |
What the next table is, and is not
It expresses the label dose and the common off-label doses for the 10 mg vial as sold, so the arithmetic can be checked against the autoinjector. The autoinjector is the approved product; the vial is not, and its identity and strength are unverified.
- Vial
- 10 mg, as sold; identity and quantity unverified unless a pharmacy dispensed it
- Water added
- 2 mL bacteriostatic water
- Concentration
- 5,000 mcg/mL (5 mg/mL). One concentration for the whole vial.
- Syringe
- 0.5 mL insulin syringe; the label dose is a 35-unit draw
| Dose | Who uses it | Draw | Units | Doses per vial |
|---|---|---|---|---|
| 0.5 mg | Men limiting nausea | 0.1 mL | 10 | 20 |
| 1 mg | Common men's dose | 0.2 mL | 20 | 10 |
| 1.75 mg | The label, women | 0.35 mL | 35 | 5 to 6 |
| 2 mg | Upper men's dose | 0.4 mL | 40 | 5 |
At the label's maximum of eight doses a month, a vial lasts three to four weeks at 1.75 mg. There is no daily protocol; this is the one peptide in the series taken by the event, not by the week.
What each draw looks like · 0.5 mL (50-unit) U-100 insulin syringe
The plunger tip sits on the line for the dose. Units are marks on a U-100 syringe: 100 units is 1 mL. The picture assumes the concentration in the table above; a different amount of water changes every line.
- The 45-minute lead time is from the label; the men's trials saw onset at about 30 minutes nasally. Effects last for hours, which is why the label caps doses per day.
- Nausea is dose-related and front-loaded: most users have it on the first dose and less on the second. Taking it on an empty stomach makes it worse.
- Skin darkening from repeated use is permanent in some users and is the reason for the monthly cap as much as blood pressure is.
Bremelanotide is an approved drug, which puts it in the same position as tesamorelin in this series and cuts the same way. The autoinjector by prescription is lawful for any use a doctor chooses. A compounded copy for men at a different dose is a gray area at best. A research vendor's vial is an unapproved drug, and FDA named PT-141 in a warning letter to a peptide seller in August 2026.
| Route | Legal position | What the buyer gets |
|---|---|---|
| Vyleesi by prescription | Approved. Off-label prescribing to men is lawful and common through telehealth | A verified 1.75 mg dose in an autoinjector, at a brand price and without insurance for men |
| Compounded PT-141 from a pharmacy | Restricted. A pharmacy may not regularly compound what is essentially a copy of an available approved drug unless a change meets a documented patient-specific need; a different dose for men is the usual justification | A cheaper vial or spray with a pharmacy label and beyond-use date |
| Research-chemical vial | An unapproved new drug. Named in FDA's August 2026 warning letter to Royal Peptides among products sold as research chemicals for human use | Unverified identity and strength, no pharmacy, no prescriber |
| Date | Event |
|---|---|
| 1990s | Erections observed as a side effect in Melanotan II volunteers; bremelanotide developed from it |
| 2004 | Nasal and injected trials in men show erectogenic effect |
| 2007 | FDA places the nasal program on clinical hold over blood-pressure increases; developer pivots to injection and to women |
| 2019 | Vyleesi approved for hypoactive sexual desire disorder in premenopausal women |
| 2025–2026 | Telehealth clinics market compounded PT-141 to men; FDA's compounding and telehealth enforcement expands |
| Aug 2026 | FDA warning letter to a peptide seller names PT-141 among unapproved drugs sold as research chemicals |
The approval belongs to the autoinjector
Sellers cite "FDA-approved" for a vial FDA has never seen, for a sex it was not approved in, at a dose the label does not contain. The approval covers one product, one dose, one population. Everything else is inference, and the inference stopped being tested in 2008.
Reading a vial: the milligram arithmetic9
PT-141 doses are in milligrams, the vial is 10 mg, and the draws are large, which makes it easy to dose and easy to overshoot. The women's label is 1.75 mg; the men's trials used several times that. A buyer who reads a forum protocol in milligrams and a syringe in units needs one conversion, and the wrong water volume doubles or halves everything.
units = (dose mg ÷ concentration mg/mL) × 100
A 10 mg vial reconstituted with 2 mL of bacteriostatic water is 5 mg/mL. The 1.75 mg label dose is 0.35 mL, or 35 units on a U-100 insulin syringe; 1 mg is 20 units.
| Water added | Concentration | 1 mg | 1.75 mg | 2 mg |
|---|---|---|---|---|
| 1 mL | 10 mg/mL | 10 units | 17.5 units | 20 units |
| 2 mL | 5 mg/mL | 20 units | 35 units | 40 units |
| 3 mL | 3.3 mg/mL | 30 units | 52.5 units | 60 units |
Reconstituted bremelanotide is a multi-dose vial used over weeks; the autoinjector is single-use and never mixed. A research vial has no beyond-use date. Refrigerate and assume degradation within weeks.
- Common
- Nausea in 40%, flushing in about 20%, headache, vomiting, injection-site reactions. Nausea led 8% of trial participants to quit.
- Blood pressure
- A transient rise of a few points in systolic and diastolic pressure after each dose, peaking within hours. Contraindicated in uncontrolled hypertension and known cardiovascular disease; the reason for the daily and monthly caps.
- Skin
- Focal darkening of the face, gums, or breasts in about 1%, more with frequent dosing, and in some users permanent. Shared with its parent, Melanotan II.
- Interactions
- Slows stomach emptying, which can reduce absorption of oral drugs taken around the same time; the label singles out naltrexone. Combining with sildenafil or tadalafil has one small study behind it.
- Men specifically
- Priapism has been reported with the parent compound, Melanotan II, and the mechanism is shared. Prolonged erections are a reason to seek care, not to wait.
- Do not use
- With uncontrolled high blood pressure or cardiovascular disease; in pregnancy, where the label advises against use; the label has no data in men, adolescents, or postmenopausal women.
- The vial
- Everything above at an unverified dose, with no sterility certification and no pharmacist to call.
- Is this the autoinjector, a compounded vial or spray, or a research vial? Who made it?
- What is my blood pressure, and has anyone checked it? Do I have heart disease?
- If I am a man: do I know that the approval is for women, at one dose, and that the men's program stopped over blood pressure?
- Is the problem desire or erection? Sildenafil and tadalafil are approved, trialed, and cheap for the second.
- Am I taking it with a sildenafil-type drug, and does anyone know?
- How many doses this month, and am I inside the label's cap of eight?
- Have I noticed any darkening of skin or gums?
What does have evidence
For erectile dysfunction in men: sildenafil, tadalafil, and the other approved PDE5 drugs, with decades of trials and generic prices. For low desire in premenopausal women: Vyleesi and the daily tablet flibanserin, both approved, both modest. For low desire in men: an evaluation of testosterone, sleep, mood, and medicines, which explain most cases and which no peptide addresses.
Latest
Developments since this edition, newest first. Items here are dated and sourced; they update the guide without re-editing it.
FDA's record shows no Vyleesi label change since 2020
The agency's approval history lists Cosette as the applicant, original approval June 21, 2019, and the last labeling supplement October 23, 2020. Vendor claims of a 2026 label revision are unsupported.
Bremelanotide was not among the July committee's peptides
The 503A bulks-list route applies only where no approved product covers the substance. Vyleesi is approved, so compounded PT-141 remains a copy of an approved drug rather than a candidate for the list.
No FDA enforcement yet against compounded bremelanotide
A regulatory explainer notes outsourcing facilities generally cannot compound it because Vyleesi is available and not in shortage, while 503A pharmacies may prepare patient-specific versions on a documented need. No FDA action against a compounder had been reported.
References
- 1.Vyleesi (bremelanotide injection) prescribing information. Cosette Pharmaceuticals, current revision. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f1d0c1b5-2f39-4bad-a6a4-0066e3ad5dcf
- 2.Hadley ME, Dorr RT. Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization. Peptides. 2006;27(4):921-930.
- 3.Kingsberg SA, et al. Bremelanotide for the treatment of hypoactive sexual desire disorder: two randomized phase 3 trials. Obstet Gynecol. 2019;134(5):899-908. https://pubmed.ncbi.nlm.nih.gov/31599840/
- 4.Simon JA, et al. Long-term safety and efficacy of bremelanotide for HSDD (RECONNECT extension). Obstet Gynecol. 2019;134(5):909-917.
- 5.Diamond LE, et al. Intranasal PT-141 in healthy males and men with mild-to-moderate erectile dysfunction: a placebo-controlled evaluation. Int J Impot Res. 2004;16(1):51-59. https://pubmed.ncbi.nlm.nih.gov/14963471/
- 6.Rosen RC, et al. Subcutaneous PT-141 in healthy men and in patients with an inadequate response to sildenafil. Int J Impot Res. 2004;16(2):135-142.
- 7.Safarinejad MR, Hosseini SY. Salvage of sildenafil failures with bremelanotide: a randomized, double-blind, placebo controlled study. J Urol. 2008;179(3):1066-1071.
- 8.Palatin Technologies. Intranasal bremelanotide clinical hold and shift to subcutaneous development, 2007-2008.
- 9.Representative PT-141 vial listings (10 mg) and dosing instructions from research-chemical vendors and telehealth clinics, September 2026.
- 10.U.S. Food and Drug Administration. Warning letter to Royal Peptides LLC, August 24, 2026 (unapproved drugs including PT-141 sold as research chemicals). https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/royal-peptides-llc-734884-08242026
- 11.U.S. Food and Drug Administration. Compounded drug products that are essentially copies of a commercially available drug product under section 503A. Guidance, 2018.
- 12.Palatin Technologies. Update on clinical programs, strategic priorities, and anticipated milestones (bremelanotide co-formulated with a PDE5 inhibitor for erectile dysfunction). Press release, September 9, 2024. https://www.biospace.com/press-releases/palatin-provides-update-on-clinical-programs-strategic-priorities-and-anticipated-milestones