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Peptide (FDA approved drug)Human trialsFDA approved

PT-141

Bremelanotide

Last reviewed October 27, 2026 · 21 sources · Written for general readers · Compare with another compound →

The bottom line

PT-141 is the same molecule as Vyleesi, an FDA approved shot for low sexual desire in premenopausal women. Two large trials showed a small but real gain in desire, but no rise in satisfying sex, and about 4 in 10 users had nausea. Claims about men, tanning and weight loss rest on small or flawed studies, and vials sold online are not Vyleesi.

Where the evidence stands

What it is

PT-141 is a lab code for bremelanotide, a small ring shaped peptide made of seven building blocks (amino acids).[1] FDA approved it in June 2019 under the brand name Vyleesi, as a single use autoinjector pen.[2] Its CAS registry number is 189691-06-3.[3]

Vyleesi is approved only for premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD), meaning low sexual desire that causes real distress and is not explained by another illness, a relationship problem or a medicine.[1] It is not approved for men, for women after menopause, or to boost sexual performance.[1]

Online, the same molecule is sold as unregulated vials labeled PT-141, often with claims about male erections, tanning and weight loss. Those vials are not the FDA approved drug, which comes only as the Vyleesi pen.[2]

Name
PT-141 (Bremelanotide)
Other names
bremelanotide, Vyleesi (approved brand)
Type
Peptide (FDA approved drug)
Sequence
Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH
CAS number
189691-06-3
Formula
C50H68N14O10
Molecular weight
About 1025.2 g/mol (free base)

What it does in the body

Bremelanotide does not occur naturally. It is a lab made peptide that switches on melanocortin receptors, which normally respond to a family of natural hormones. At the amounts used in treatment, its main targets are MC4R in the brain and MC1R on skin pigment cells.[1]

This is the biology, area by area. A change measured in the body, like a higher blood level, does not always mean a person feels a benefit. The claims check below covers that.

Brain and sexual desire

Measured in people

In a placebo controlled crossover study of 31 premenopausal women with HSDD, the drug raised sexual desire for up to 24 hours. Brain scans while watching erotic videos showed more activity in the cerebellum and a movement planning area, less in a touch processing area, and stronger links between the amygdala and the insula, two areas tied to emotion.[6] In female rats it increased behaviors that invite mating without changing general activity.[5]

Sexual function in men

Measured in people

In an early placebo controlled study, a single nasal spray produced more erections than placebo in healthy men and men with mild to moderate erectile dysfunction.[7] In male rats and monkeys, the drug given into the body also produced erections.[8]

Skin

Measured in people

Because it switches on MC1R on pigment cells, it raises melanin in the skin.[1] Patchy darkening of the face, gums or breasts appeared in 1% of women using it as needed, in 38% after 8 days of daily use, and in another 14% after 8 more days. It was more common in darker skin and did not always fade.[1]

Heart and blood vessels

Measured in people

Blood pressure rises for a few hours after each dose, by up to about 6 points on the top number and 3 on the bottom, peaking 2 to 4 hours after a dose and usually settling within 12 hours. Heart rate drops slightly.[1] A monitoring study in 397 women confirmed small, short lived rises.[9]

Gut

Measured in people

Nausea is the main side effect, reported by 40% of women versus 1.3% on placebo. It usually starts within an hour, lasts about two hours, and is most common after the first dose (21%), falling to about 3% with later doses.[1]

Appetite and weight

Measured in people

Two short phase 1 trials in women with obesity found the drug cut food intake by about 400 calories a day. In the 16 day trial, women lost about 1.3 kg more than on placebo.[4]

How it works

Bremelanotide switches on several melanocortin receptors. These are docking sites on cells that respond to a family of natural hormones.[1]

  • It activates five melanocortin receptors, most strongly MC1R, then MC4R, MC3R, MC5R and MC2R. At the amounts used in treatment, MC1R and MC4R matter most.[1]
  • MC4R is found in the brain. MC1R sits on pigment cells in the skin, which is why the drug can darken patches of skin.[1]
  • MC4R also helps control appetite, which is why researchers tested whether the drug lowers food intake.[4]
  • In female rats, the drug acted on brain areas tied to sexual motivation rather than on the genitals directly.[5]
  • The FDA label says exactly how it improves sexual desire is unknown.[1]

The receptor targets are well measured, but the link from those receptors to desire in people is not proven.

What the research shows

We keep animal and human evidence apart. A result in animals is a reason to study something in people, not proof that it works in people.

Animal and lab studies

Rodent work showed more sexual interest, plus safety signals in pregnancy

  • In female rats, PT-141 increased behaviors where the female invites mating, without changing other sexual behaviors or general activity.[5]
  • In male rats and in monkeys, the drug given into the body produced erections.[8]
  • In female hamsters, it did not boost a learned preference for a place linked with sex, and it did not change receptor levels in the brain's reward circuit.[16]
  • In pregnant dogs, the drug caused fetal loss at exposures at least 16 times the highest human exposure. In mice, offspring had developmental delays at about 125 times the human exposure.[1]
  • Two year studies in rats and mice found no clear rise in tumors, and lab tests found no damage to DNA.[1]

Limit: Animal sexual behavior tests do not show how much a person will feel, and animal safety findings do not show how often the same problems happen in people.

Human studies

Large trials in women showed a modest benefit; data in men are thin

  • Two identical phase 3 trials (called RECONNECT) randomly assigned 1,267 premenopausal women with HSDD to bremelanotide or a dummy shot, self injected under the skin as needed, for 24 weeks.[10]
  • On the desire part of a standard sexual function questionnaire, women on the drug improved by about 0.5 to 0.6 points, compared with about 0.2 points on placebo. Distress about low desire also fell more with the drug.[1]
  • The number of satisfying sexual events did not differ between drug and placebo in either trial.[1]
  • Many women stopped early. About 4 in 10 on the drug quit during the main phase, compared with 13% and 25% on placebo. About 18% on the drug stopped because of side effects, versus 2% on placebo.[1]
  • An independent 2021 reanalysis of the phase 3 data found that women on the drug had about 12 times the odds of stopping because of side effects, and that women on placebo were more likely to finish and join the follow up. It also found most planned outcomes were never reported, and concluded the drug is generally not useful.[12]
  • Of 856 women who finished the main trials, 684 joined a 52 week open label extension, where everyone knew they got the drug, and 272 completed it. Desire scores kept improving, and no new safety problems appeared.[17] Gains held across most subgroups by age, weight and testosterone level.[18]
  • An earlier 12 week trial in 327 premenopausal women found that the two higher dose groups combined had about 0.7 more satisfying sexual events per month, compared with 0.2 more on placebo.[13]
  • In a small crossover study of 18 women with arousal problems, more women reported moderate or high desire after a single nasal spray of the drug than after placebo. Measured genital blood flow did not change significantly.[19]
  • In a 2022 crossover brain scan study of 31 women with HSDD, desire rose for up to 24 hours after the drug compared with placebo, and brain responses to erotic videos changed in ways the authors linked to more sexual imagery and less self consciousness.[6]
  • In men, an early placebo controlled study of a nasal spray in healthy men and men with erectile dysfunction found more erections than placebo, with flushing and nausea as the most common side effects.[7] A larger trial of 342 men who did not respond to sildenafil reported a good response in 33.5% on the drug versus 8.5% on placebo, but the journal later issued a formal expression of concern about that paper.[14][15]
  • Two small, short phase 1 trials in women with obesity found the drug cut food intake by about 400 calories a day. In the 16 day trial, women lost about 1.3 kg more than on placebo.[4]

Limit: The large trials were funded by the drug makers and studied only premenopausal women, so results do not apply to men, older women or other uses.

Claims check

The most common claims about this compound, and what studies actually found. Verdicts rate the evidence, not whether you should use it.

Boosts sexual desire in women

Shown in people

Two placebo controlled phase 3 trials in 1,267 premenopausal women with HSDD ran for 24 weeks.[10] Desire scores rose about 0.5 to 0.6 points on the drug versus about 0.2 on placebo, and distress about low desire fell more.[1] A 2026 meta analysis of female sexual dysfunction treatments also found better desire and arousal scores.[11] The effect is real but small, an independent reanalysis argued it is generally not useful, and this is the only use FDA approved.[12]

Leads to more satisfying sex

Mixed results

In the two large phase 3 trials, the number of satisfying sexual events did not differ from placebo, and the median was zero in every group.[1] An earlier 12 week trial in 327 women found a small rise of about 0.7 events per month versus 0.2 on placebo in the higher dose groups.[13] The larger, later trials carry more weight.

Improves erections and libido in men

Mixed results

An early placebo controlled nasal spray study found more erections than placebo in men.[7] A trial of 342 men who failed sildenafil reported 33.5% good responses on the drug versus 8.5% on placebo, but that paper is under a journal expression of concern.[14][15] The drug is not approved for men.

Helps with weight loss

Mixed results

Two small phase 1 trials in women with obesity lasted from about 4 to 16 days.[4] In the longer trial, women lost about 1.3 kg more than on placebo and ate about 400 fewer calories a day.[4] We found no published long term weight loss trial.

Gives a natural tan

Not tested

No study has tested bremelanotide as a tanning agent. What trials did find is patchy darkening of the face, gums or breasts as a side effect. This happened in 1% of women with normal use and in 38% when it was taken daily for 8 days, and it did not always fade.[1]

Known risks and side effects

  • Nausea is very common. About 40% of women had nausea, versus 1% on placebo. It usually started within an hour and lasted about two hours. About 13% needed nausea medicine and 8% quit because of it.[1]
  • Flushing, headache and vomiting. In the main trials, 20% had flushing, 11% had headache, 13% had injection site reactions and about 5% vomited, all more often than on placebo.[1] One case of acute hepatitis (liver inflammation) occurred in the open label extension, and the label says the drug could not be ruled out as the cause.[1]
  • Blood pressure rises for a few hours. Blood pressure rose by up to about 6 points systolic and heart rate dropped slightly, peaking 2 to 4 hours after a dose and usually settling within 12 hours.[1] A monitoring study in 397 women confirmed small, short rises.[9] The label says not to use it with uncontrolled high blood pressure or known heart disease.[1]
  • Dark patches of skin. Darkened patches on the face, gums or breasts appeared in about 1% with normal use, but in over a third of women given it daily for many days. People with darker skin were more likely to get it, and it did not always fade.[1][20]
  • Drug interactions and unregulated vials. Bremelanotide can lower the level of naltrexone and indomethacin taken by mouth.[20] The only FDA approved form is the Vyleesi pen.[2] Vials sold online as PT-141 are not that product, so their purity, strength and sterility are unknown. FDA's 2026 compounding list does not place bremelanotide in any category under review.[21]

Regulatory status

Today: Vyleesi is FDA approved and still marketed by prescription, now under the company Cosette, with a patient leaflet update approved on October 22, 2026.[2] It is approved only for premenopausal women with HSDD.[1]

  1. FDA approved Vyleesi (bremelanotide) as a new molecular entity.[2]
  2. FDA approved an updated Vyleesi prescribing label.[2]
  3. The Journal of Urology issued an expression of concern about the 2008 trial of bremelanotide in men.[15]
  4. FDA approved updated patient labeling for Vyleesi.[2]

Sources

  1. U.S. Food and Drug Administration. VYLEESI (bremelanotide injection) prescribing information. Revised 10/2020. FDA label, NDA 210557
  2. U.S. Food and Drug Administration. Drugs@FDA: VYLEESI, NDA 210557. Drugs@FDA
  3. U.S. FDA and NCATS Global Substance Registration System (GSRS). Bremelanotide, UNII 6Y24O4F92S. FDA GSRS
  4. Spana C, Jordan R, Fischkoff S. Effect of bremelanotide on body weight of obese women: Data from two phase 1 randomized controlled trials. Diabetes Obes Metab. 2022;24(6):1084-1093. PMID 35170192
  5. Pfaus JG, Shadiack A, Van Soest T, Tse M, Molinoff P. Selective facilitation of sexual solicitation in the female rat by a melanocortin receptor agonist. Proc Natl Acad Sci U S A. 2004;101(27):10201-10204. PMID 15226502
  6. Thurston L, Hunjan T, Mills EG, et al. Melanocortin 4 receptor agonism enhances sexual brain processing in women with hypoactive sexual desire disorder. J Clin Invest. 2022;132(19):e152341. PMID 36189794
  7. Diamond LE, Earle DC, Rosen RC, Willett MS, Molinoff PB. Double-blind, placebo-controlled evaluation of the safety, pharmacokinetic properties and pharmacodynamic effects of intranasal PT-141, a melanocortin receptor agonist, in healthy males and patients with mild-to-moderate erectile dysfunction. Int J Impot Res. 2004;16(1):51-59. PMID 14963471
  8. Molinoff PB, Shadiack AM, Earle D, Diamond LE, Quon CY. PT-141: a melanocortin agonist for the treatment of sexual dysfunction. Ann N Y Acad Sci. 2003;994:96-102. PMID 12851303
  9. White WB, Myers MG, Jordan R, Lucas J. Usefulness of ambulatory blood pressure monitoring to assess the melanocortin receptor agonist bremelanotide. J Hypertens. 2017;35(4):761-768. PMID 27977473
  10. 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. PMID 31599840
  11. Toledo RG, Winkelman WD, Reyes-Gonzalez D, Bergeron S, Fladger A, Hacker MR, Anand M. Female Sexual Desire, Arousal, and Orgasmic Dysfunctions: A Systematic Review and Meta-Analysis of Treatment Options. J Minim Invasive Gynecol. 2026;33(1):16-33.e3. PMID 40543759
  12. Spielmans GI. Re-Analyzing Phase III Bremelanotide Trials for "Hypoactive Sexual Desire Disorder" in Women. J Sex Res. 2021;58(9):1085-1105. PMID 33678061
  13. Clayton AH, Althof SE, Kingsberg S, DeRogatis LR, Kroll R, Goldstein I, Kaminetsky J, Spana C, Lucas J, Jordan R, Portman DJ. Bremelanotide for female sexual dysfunctions in premenopausal women: a randomized, placebo-controlled dose-finding trial. Womens Health (Lond). 2016;12(3):325-337. PMID 27181790
  14. Safarinejad MR, Hosseini SY. Salvage of sildenafil failures with bremelanotide: a randomized, double-blind, placebo controlled study. J Urol. 2008;179(3):1066-1071. PMID 18206919
  15. Safarinejad MR, Hosseini SY. Expression of Concern: Salvage of Sildenafil Failures With Bremelanotide: A Randomized, Double-Blind, Placebo Controlled Study. J Urol. 2023. PMID 36626345
  16. Borland JM, Kohut-Jackson AL, Peyla AC, Hall MA, Mermelstein PG, Meisel RL. Female Syrian hamster analyses of bremelanotide, a US FDA approved drug for the treatment of female hypoactive sexual desire disorder. Neuropharmacology. 2025;267:110299. PMID 39793696
  17. Simon JA, Kingsberg SA, Portman D, Williams LA, Krop J, Jordan R, Lucas J, Clayton AH. Long-Term Safety and Efficacy of Bremelanotide for Hypoactive Sexual Desire Disorder. Obstet Gynecol. 2019;134(5):909-917. PMID 31599847
  18. Simon JA, Kingsberg SA, Portman D, Jordan R, Lucas J, Sadiq A, Krop J, Clayton AH. Prespecified and Integrated Subgroup Analyses from the RECONNECT Phase 3 Studies of Bremelanotide. J Womens Health (Larchmt). 2022;31(3):391-400. PMID 35230162
  19. Diamond LE, Earle DC, Heiman JR, Rosen RC, Perelman MA, Harning R. An effect on the subjective sexual response in premenopausal women with sexual arousal disorder by bremelanotide (PT-141), a melanocortin receptor agonist. J Sex Med. 2006;3(4):628-638. PMID 16839319
  20. Clayton AH, Kingsberg SA, Portman D, Sadiq A, Krop J, Jordan R, Lucas J, Simon JA. Safety Profile of Bremelanotide Across the Clinical Development Program. J Womens Health (Larchmt). 2022;31(2):171-182. PMID 35147466
  21. U.S. Food and Drug Administration. Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the FD&C Act (categories list). Updated May 14, 2026. FDA 503A categories
Medical disclaimer

This page is educational information only. It is not medical advice and does not replace care from a licensed medical provider. Do not use this page to decide whether to take any substance. Talk to a licensed medical provider first.

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