PT-141 Side Effects and Benefits: Research Data
What the bremelanotide label and trials report on nausea, flushing, blood pressure and skin darkening, what the HSDD and erectile dysfunction studies found, and where PT-141 stands with regulators.
Update History ▾
Research-use-only framing applied throughout in line with Remy editorial standards.
PT-141 side effects are better documented than those of most research peptides, because PT-141 is bremelanotide, the active ingredient of Vyleesi. In the two phase 3 trials behind its FDA approval, nausea affected 40% of women given bremelanotide against 1.3% on placebo, flushing 20.3% against 0.3%, and headache 11.3% against 1.9%. Blood pressure rises briefly after each dose, and about 1% developed focal darkening of the skin.[1][2]
The approved use is narrow: treatment of premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD). The label states it is not indicated for men, for postmenopausal women or to enhance sexual performance.[1] Studies in men exist but are small and older. Remy Research supplies PT-141 for in-vitro laboratory research only.
What Is PT-141 (Bremelanotide)?
PT-141 is the development code for bremelanotide, a synthetic cyclic heptapeptide derived from alpha melanocyte stimulating hormone (α-MSH).[3][1] It was developed from Melanotan II, an earlier α-MSH analogue studied for tanning and erections.[4] FDA approved it under the brand name Vyleesi on June 21, 2019 for the treatment of HSDD in premenopausal women.[5][1]
Three names refer to one molecule: PT-141 is the research code, bremelanotide the generic name, and Vyleesi the approved US product. The adverse-event figures in this article come from the Vyleesi label and the clinical trials that supported it, which enrolled patients, not healthy volunteers.
How PT-141 Works on Melanocortin Receptors
Bremelanotide activates several melanocortin receptors, in the order of potency MC1R, MC4R, MC3R, MC5R, MC2R; at therapeutic levels the label says binding to MC1R and MC4R matters most.[1] Early work placed its sexual effects in the central nervous system: in rats it activated neurons in the hypothalamus, and MC3R and MC4R are expressed mainly in the brain.[3] That central nervous system profile is why it was framed as a different approach from oral medications that act on penile blood flow and the vascular system.[3][6]
The label is blunt about one point: the mechanism by which it improves HSDD in women is unknown.[1] MC1R on pigment cells explains the darkening of skin seen in some users, and MC4R activation is linked to the rise in blood pressure.[1][7]
PT-141 Benefits Studied in Clinical Trials
| Area studied | What was reported | Evidence type |
|---|---|---|
| Sexual desire | Higher desire scores than placebo in two 24-week trials of 1,247 women | Human phase 3 |
| Desire-related distress | Lower distress scores than placebo in the same trials | Human phase 3 |
| Satisfying events | +0.7 against +0.2 a month over 12 weeks | Human phase 2 |
| Erectile response | Erections on monitoring in healthy men and men with mild ED | Human phase 1/2 |
| Sildenafil non-response | 33.5% against 8.5% responders; paper under expression of concern | Human RCT |
| Animal models | Erections in rats and non-human primates | Animal |
Low Libido and Sexual Desire: Hypoactive Sexual Desire Disorder in Premenopausal Women
The RECONNECT program ran two identical 24-week, randomized, placebo-controlled trials in premenopausal women with hypoactive sexual desire disorder (HSDD), a form of low libido in which decreased sexual desire causes marked distress. Patients were mostly white, from US sites, with a mean age of 39. Of 1,267 women randomized, 1,247 formed the safety population. The co-primary endpoints were the Female Sexual Function Index desire domain and item 13 of the Female Sexual Distress Scale–Desire/Arousal/Orgasm, which asks how bothered patients feel by low desire. Compared with placebo, bremelanotide raised desire scores by 0.30 and 0.42 points in the two studies and lowered distress by 0.37 and 0.29 points, all statistically significant.[2] These are modest average changes on rating scales, and the label defines a responder as a gain of at least 1.2 points on the desire domain.[1]
An earlier 12-week dose-finding trial in premenopausal women with female sexual dysfunction reported more satisfying sexual events per month (+0.7 against +0.2 with placebo), higher sexual function index scores and lower distress scores, with nausea, flushing and headache as the main adverse events.[8]
PT-141 for Men: Erectile Function and Erectile Dysfunction Studies
The men’s data are research findings, not an approved use. In placebo-controlled studies of a nasal spray form, PT-141 (bremelanotide) produced a dose-dependent erectile response, measured by RigiScan, in healthy men and in men with mild-to-moderate erectile dysfunction who responded to Viagra, tested during visual sexual stimulation; flushing and nausea were the most common adverse events.[9] A 2008 randomized trial of 342 men whose erectile dysfunction had not responded to sildenafil reported positive results in 33.5% on bremelanotide against 8.5% on placebo, using the International Index of Erectile Function, with more drug-related adverse effects in the bremelanotide group.[10] The journal has since issued an expression of concern about that paper.[10]
No phase 3 trial in men led to an approval, and the current label says Vyleesi is not indicated in men.[1] A 2026 review of 76 studies described bremelanotide as one of the most clinically established peptides in sexual medicine, while noting that safety data across the field are limited by short follow-up and small samples.[6]
PT-141 Side Effects: What the FDA Label Reports
| Adverse reaction | Bremelanotide (n=627) | Placebo (n=620) |
|---|---|---|
| Nausea | 40.0% | 1.3% |
| Flushing | 20.3% | 0.3% |
| Injection site reactions | 13.2% | 8.4% |
| Headache | 11.3% | 1.9% |
| Vomiting | 4.8% | 0.2% |
| Cough | 3.3% | 1.3% |
| Fatigue | 3.2% | 0.5% |
| Hot flush | 2.7% | 0.2% |
| Dizziness | 2.2% | 0.5% |
- Nausea. The most common adverse reaction. It needed anti-emetic therapy in 13% of patients and caused 8% to leave the trials; for most it improved with the second dose.[1]
- Blood pressure and heart rate. Bremelanotide raised systolic blood pressure by up to 6 mmHg and diastolic blood pressure by up to 3 mmHg, peaking 2 to 4 hours after a dose, with heart rate falling by up to 5 beats per minute; values usually returned to baseline within 12 hours.[1] A 397-woman ambulatory monitoring study found the same small, transient pattern.[7]
- Focal hyperpigmentation. Reported in 1% of women, including the face, gums and breasts. The risk was higher with darker skin and more frequent use, and resolution was not confirmed in some.[1]
- Discontinuation. 18% of patients stopped treatment because of adverse reactions, against 2% on placebo. Serious adverse reactions occurred in 1.1% against 0.5%.[1]
- Liver. One case of acute hepatitis was reported in the open-label extension.[1]
In those trials 627 patients received bremelanotide and 620 received placebo, so the table compares treatment and placebo groups directly.[1]
The label lists uncontrolled hypertension and known cardiovascular disease as contraindications, does not recommend it for people at high risk of cardiovascular disease, and warns that PT-141 may sharply reduce blood levels of oral naltrexone, so it should be avoided with naltrexone medications used to treat alcohol or opioid addiction.[1]
FDA Approval: Is PT-141 FDA Approved?
- FDA approval. Yes, as Vyleesi, approved June 21, 2019, for premenopausal women with acquired, generalized HSDD only.[5][1]
- Not approved for. Men, postmenopausal women, or enhancing sexual performance; any such use would be off label.[1]
- Sport. Bremelanotide is not named on WADA’s 2027 Prohibited List; class S0 covers only substances with no current approval for human therapeutic use.[11]
- UAE. Remy Research sells PT-141 for in-vitro laboratory research only, not for human or veterinary use.
PT-141 vs Related Compounds
PT-141 is most often compared with Melanotan II, from which it was developed. Both act on melanocortin receptors, but Melanotan II has no approval and its safety record rests mainly on case reports; see PT-141 vs Melanotan II.[4] Kisspeptin is a separate research avenue for low sexual desire. Kisspeptin-10 raised LH and testosterone in healthy men,[12] and in a 2023 crossover trial of 32 men with HSDD, kisspeptin changed brain responses to sexual images and increased penile tumescence compared with placebo.[13] See HCG vs gonadorelin vs kisspeptin and the oxytocin research review.
Gaps in the Clinical Evidence
- A confirmed benefit in men. The male studies are small, early-phase or under an expression of concern, and none led to an approved treatment.[9][10][1]
- A known mechanism. How bremelanotide improves desire in HSDD is still unknown.[1]
- Long-term safety outside the label. Follow-up across sexual-medicine peptides is short, and cardiovascular outcomes have not been studied at length.[6]
These gaps are reasons to describe the evidence carefully, not reasons to dismiss it.
PT-141 for Laboratory Research
Remy Research supplies PT-141 for in-vitro research as the PT-141 10mg research vial, the PT-141 20mg pen and the Genovare PT-141 50mg AQ pen. Each product page carries its batch testing details. For receptor pharmacology and the full development history, read the PT-141 melanocortin research review.
Our Research Standards
This article prioritizes the approved prescribing information, randomized trials and regulator records, and keeps approved, trial and animal evidence apart. Adverse-event figures are quoted as reported. No therapeutic, dosing or administration guidance is given. Read our editorial policy →
PT-141 Side Effects FAQ
What are the side effects of PT-141?
In the phase 3 trials the most common were nausea (40%), flushing (20.3%), injection site reactions (13.2%), headache (11.3%) and vomiting (4.8%). The label also lists a brief rise in blood pressure after each dose and focal skin darkening in about 1%.[1]
Does PT-141 increase blood pressure?
Is PT-141 FDA approved?
Is PT-141 safe?
Its safety profile is defined for the approved use in premenopausal women: it is contraindicated with uncontrolled hypertension or known cardiovascular disease, and 18% left the trials because of adverse reactions. Safety outside that use has not been established.[1]
Is PT-141 for men?
Does PT-141 make you tan?
It is not a tanning agent, but it activates MC1R on pigment cells, and about 1% of women in the trials developed focal hyperpigmentation of the face, gums or breasts.[1]
What is the half-life of PT-141?
The label gives a mean terminal half-life of about 2.7 hours (range 1.9 to 4.0 hours) after a single dose, with peak levels at about 1 hour.[1]
Sources
- DailyMed. VYLEESI (bremelanotide injection) prescribing information, Cosette Pharmaceuticals; label revised March 2024. U.S. National Library of Medicine. dailymed.nlm.nih.gov ↩
- Kingsberg SA, Clayton AH, Portman D, Williams LA, Krop J, Jordan R, Lucas J, Simon JA. Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials. Obstet Gynecol. 2019;134(5):899-908. doi: 10.1097/AOG.0000000000003500 · PMID: 31599840 ↩
- 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. doi: 10.1111/j.1749-6632.2003.tb03167.x · PMID: 12851303 ↩
- Hadley ME, Dorr RT. Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization. Peptides. 2006;27(4):921-930. doi: 10.1016/j.peptides.2005.01.029 · PMID: 16412534 ↩
- U.S. Food and Drug Administration. Approval Package for NDA 210557: Vyleesi (bremelanotide) subcutaneous injection. Approval date June 21, 2019. accessdata.fda.gov ↩
- Vasylieva V, West A, Karpman E. Peptides in urology and sexual medicine: clinical effectiveness, dosing, indications, and safety: a narrative review. Sex Med Rev. 2026;14(4):qeag078. doi: 10.1093/sxmrev/qeag078 · PMID: 42862021 ↩
- 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. doi: 10.1097/HJH.0000000000001221 · PMID: 27977473 ↩
- Clayton AH, Althof SE, Kingsberg S, et al. Bremelanotide for female sexual dysfunctions in premenopausal women: a randomized, placebo-controlled dose-finding trial. Womens Health (Lond). 2016;12(3):325-337. doi: 10.2217/whe-2016-0018 · PMID: 27181790 ↩
- 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. doi: 10.1038/sj.ijir.3901139 · PMID: 14963471 ↩
- Safarinejad MR, Hosseini SY. Salvage of sildenafil failures with bremelanotide: a randomized, double-blind, placebo controlled study. J Urol. 2008;179(3):1066-1071. doi: 10.1016/j.juro.2007.10.063 · PMID: 18206919 The journal published an expression of concern about this article in 2023. ↩
- World Anti-Doping Agency. 2027 Prohibited List, in force from January 1, 2027 (bremelanotide is not named; class S0 covers substances with no current governmental approval for human therapeutic use). wada-ama.org ↩
- George JT, Veldhuis JD, Roseweir AK, et al. Kisspeptin-10 is a potent stimulator of LH and increases pulse frequency in men. J Clin Endocrinol Metab. 2011;96(8):E1228-E1236. doi: 10.1210/jc.2011-0089 · PMID: 21632807 ↩
- Mills EG, Ertl N, Wall MB, et al. Effects of Kisspeptin on Sexual Brain Processing and Penile Tumescence in Men With Hypoactive Sexual Desire Disorder: A Randomized Clinical Trial. JAMA Netw Open. 2023;6(2):e2254313. doi: 10.1001/jamanetworkopen.2022.54313 · PMID: 36735255 ↩
For catalog details, see the PT-141 10mg research vial, the PT-141 20mg pen and the Genovare PT-141 50mg AQ pen. For editorial standards, continue to the editorial policy.