PT-141: Uses, Evidence, Dosing & Safety

Q: What does PT-141 actually feel like?

In trials, the effect is best described as an increase in *desire* and *interest*, not a guaranteed physical response. Modest in size on a population level, the average improvement over placebo on the FSFI-Desire scale was roughly 0.35 points, and bundled with a high rate of nausea (~40%) and transient blood-pressure increases. It is not a switch.

01 What is PT-141?

In plain English.

PT-141, generic name bremelanotide, brand name Vyleesi, is a small synthetic peptide originally derived from melanotan II (the "tanning peptide"). Researchers in the early 2000s noticed melanotan II was producing unexpected sexual-arousal effects in trials aimed at skin pigmentation. Palatin Technologies refined the arousal-related activity into a cleaner molecule, PT-141. In 2019 the FDA approved it as Vyleesi for one specific use: hypoactive sexual desire disorder (HSDD) in premenopausal women. It is given as a self-injection in the thigh or abdomen at least 45 minutes before anticipated sexual activity. It is not approved for men, despite very widespread off-label and gray-market use.

⏱ Half-life

~2.7 hours

☉ Route

Subcutaneous auto-injector

⚖ Evidence

Approved (women only) · two Phase 3 RCTs

📚 Studies

6 referenced

PT-141 is often confused with melanotan II, they are related cousins. Melanotan II is the broader, unregulated MC1R-dominant compound used (illegally and unsafely) for skin tanning; PT-141 is the refined, FDA-approved descendant with most of the tanning activity engineered out. They are not interchangeable, and "PT-141" sold by research-chemical sites is not necessarily what is in a Vyleesi auto-injector.

02 How it works

The simple version, then the science.

Unlike sildenafil (Viagra), which works on blood flow in the penis, PT-141 acts on the brain. It activates melanocortin receptors, particularly MC4R, in hypothalamic circuits involved in sexual desire and arousal. The result is centrally-mediated increase in subjective desire, not a peripheral effect on erection or lubrication. This is why it can (in principle) work in people whose problem is "I do not want to" rather than "the equipment will not cooperate", but also why the measurable effect on physical sexual response is more modest than people often expect.

Go deeper · the proposed mechanism

Bremelanotide is a cyclic heptapeptide, Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH, derived from α-melanocyte-stimulating hormone (α-MSH) via the parent melanotan II. It is a non-selective agonist at MC1R, MC3R, MC4R and MC5R, with the central pro-sexual effect mediated chiefly by MC4R-expressing neurons in the medial preoptic area and paraventricular nucleus of the hypothalamus. Subcutaneous bioavailability is approximately 100% and plasma half-life is around 2.7 hours. Off-target MC1R activity is responsible for the focal hyperpigmentation seen with repeat dosing; MC4R activity in autonomic centres is responsible for the transient rise in blood pressure that drives the cardiovascular contraindications on the label.

03 What it's used for

Each use graded by how strong the evidence actually is.

Approved
Hypoactive sexual desire disorder (HSDD) in premenopausal womenFDA-approved June 2019 as Vyleesi for the as-needed treatment of acquired, generalised HSDD in premenopausal women. Based on the two RECONNECT phase 3 trials (Kingsberg et al. 2019). Effect size is real but modest, a treatment-vs-placebo difference of roughly 0.35 points on the FSFI-Desire scale and 0.27 on FSDS-DAO Q13, and around 18% of patients on active treatment discontinued because of nausea or other side effects.
Limited
Male erectile dysfunction (off-label)Earlier phase 2 work in the 2000s with intranasal bremelanotide in men with ED showed some signal but was discontinued during development because of dose-related transient blood-pressure increases. There are no large modern phase 3 trials in men. Off-label prescribing and very widespread gray-market use exists, but the evidence for the male indication is several rungs below the female one.
Preclinical
Haemorrhagic shock / ischaemia–reperfusionPalatin and academic groups have explored melanocortin agonism for reperfusion injury and shock; this remains preclinical / very early clinical and is not a near-term indication.
Anecdotal
Generic "libido enhancer" / recreational useA large gray-market trade markets PT-141 as a general-purpose libido enhancer for both sexes, sometimes alongside melanotan II for tanning. This is unapproved, the products are unverified, and routine repeat dosing risks blood-pressure effects and the characteristic focal hyperpigmentation.

▸

Approved for women, used by men. The honest picture: PT-141 has one FDA-approved indication, in premenopausal women with HSDD. The male use case is off-label and rests on small, dated trials. If you have read a confident article claiming PT-141 is "the male Viagra," it is overstating the evidence.

04 What the evidence says

The pivotal evidence is the RECONNECT programme: two identical phase 3, double-blind, placebo-controlled trials (Studies 301 and 302, NCT02333071 / NCT02338960) in 1,247 premenopausal women with acquired, generalised HSDD, published together by Kingsberg et al. in Obstetrics & Gynecology in 2019. Across both trials, bremelanotide 1.75 mg as needed produced statistically significant but numerically modest improvements over placebo on the two co-primary endpoints, FSFI-Desire and the FSDS-DAO Q13 distress item, with treatment-vs-placebo differences in the 0.27 to 0.35 range on those scales. A 52-week open-label extension (Simon et al. 2019) reported no new safety signals but documented nausea in 40% of users and high overall discontinuation. A 2022 subgroup analysis confirmed the effect was broadly consistent across age, race and baseline severity. The honest caveats: trials are sponsor-run, effect sizes are small, dropout because of nausea is high, the regulatory dataset is essentially women-only, and no comparable phase 3 evidence exists in men. EMA and MHRA have not licensed it.

05 Dosing & administration

Reported in the literature, information not advice.

For information only, Vyleesi is a prescription medicine in the US, and dosing should be set by a clinician, not by reading a webpage. The FDA label specifies one 1.75 mg subcutaneous injection at least 45 minutes before anticipated sexual activity, with no more than one dose in 24 hours and no more than eight doses per month. Use beyond eight weeks without a response is not recommended. Self-dosing from unregulated suppliers is unsafe: the products sold as "PT-141" on research-chemical sites are not verified to be the same molecule, dose or purity as Vyleesi, and the cardiovascular and pigmentation cautions on the label exist for good reasons.

06 Side effects & safety

The dose-limiting side effect is nausea, reported by about 40% of patients in the long-term extension; flushing (~20%) and headache (~12%) are also common. Around 18% of treated patients in RECONNECT discontinued because of adverse events, versus 2% on placebo, a meaningful real-world signal. Bremelanotide transiently increases blood pressure (typically peaking 2–4 hours after a dose) and reduces heart rate, and is therefore contraindicated in uncontrolled hypertension or known cardiovascular disease. With repeat dosing, focal hyperpigmentation, darkening of the face, gums or breasts, can occur, mediated by off-target MC1R activity; it may not fully resolve after stopping. The phase-3 safety dataset is overwhelmingly in women; the safety profile for chronic male use is not characterised at FDA-grade. Not for use in pregnancy.

▸

Research-chemical PT-141 ≠ Vyleesi. Vials sold online as "PT-141" are not pharmaceutical-grade Vyleesi. Purity, identity and dose are not guaranteed. The cardiovascular and pigmentation risks on the FDA label apply at least as much to the unregulated product, possibly more.

07 Where to buy (research use only)

Vetted on quality and transparency, not an endorsement to use.

US: prescribing clinician + licensed pharmacy (Vyleesi)

In the US, Vyleesi is dispensed against a prescription through a licensed pharmacy, typically a specialty or telehealth route. This is the only channel where you can be sure you are getting the molecule and the QC the FDA reviewed in 2019. Currently US-licensed via Cosette Pharmaceuticals (rights moved from Palatin → AMAG → Cosette).

Prescription-onlyFDA-approved productNo commission paid to Pepwyse

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UK / EU / AUS: no approved channel exists

PT-141 is not licensed by the MHRA, EMA or TGA. There is no compliant pharmacy supply outside the US. In practice, UK and EU buyers are purchasing research-chemical PT-141 from peptide vendors, those products are sold "for research use only", are not subject to pharmaceutical QC, and are not equivalent to Vyleesi. Pepwyse does not endorse this route; speak to a doctor about licensed alternatives for sexual function concerns.

No licensed supply outside USResearch-chemical onlyNot endorsed

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Disclosure: Pepwyse is not affiliated with these companies and does not earn any commission from these links; they are listed for reference only. These products are sold strictly for laboratory research use only and are not for human consumption.

08 Legal & regulatory status

UK
Not licensed by the MHRA. No approved medicinal product containing bremelanotide is on the UK market. Material sold as "PT-141" is research-chemical only and not legal to supply for human use.
US
FDA-approved (June 2019, NDA 210557) as Vyleesi (bremelanotide injection) for the as-needed treatment of HSDD in premenopausal women. Prescription-only. Use in men is off-label.
EU
Not EMA-approved. No centrally authorised medicinal product across EU member states. Research-chemical PT-141 is not a regulated medicine.
Sport
Bremelanotide is not specifically named on the WADA 2026 Prohibited List. Athletes under WADA jurisdiction should still verify the current published list, peptide hormone categories evolve year-to-year, and consider declaration if used therapeutically.

09 Clinical studies & research

Primary sources. Read the science yourself.

RECONNECT: Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder, Two Randomized Phase 3 Trials

Obstetrics & Gynecology · 2019 Human · Phase 3 RCT

1,247 premenopausal women with acquired, generalised HSDD across two identical phase 3 trials (Studies 301 and 302). Bremelanotide 1.75 mg SC as needed produced statistically significant but modest improvements over placebo on FSFI-Desire and FSDS-DAO Q13. Basis for the 2019 FDA approval. Kingsberg SA, Clayton AH, Portman D, et al. doi:10.1097/AOG.0000000000003500. View on PubMed →

Long-Term Safety and Efficacy of Bremelanotide for Hypoactive Sexual Desire Disorder

Obstetrics & Gynecology · 2019 Human · 52-week open-label extension

52-week open-label extension of 684 RECONNECT completers. No new safety signals. Nausea 40.4%, flushing 20.6%, headache 12.0%; nausea was the only severe TEAE reported by more than one participant. Simon JA, Kingsberg SA, Portman D, et al. View on PubMed →

Patient Experience of Premenopausal Women Treated with Bremelanotide for HSDD: RECONNECT Exit Study

Journal of Women's Health · 2021 Human · qualitative exit interviews

Exit-interview study capturing patient-reported benefit and tolerability from the RECONNECT trials. Reinforces that the patient-meaningful benefit is real but coexists with high nausea-driven discontinuation. Kingsberg SA et al. View on PubMed →

Prespecified and Integrated Subgroup Analyses from the RECONNECT Phase 3 Studies of Bremelanotide

Journal of Women's Health · 2022 Human · subgroup analysis

Pre-specified subgroup analyses across age, race/ethnicity, baseline HSDD severity and prior treatment status. Effects on FSFI-Desire and FSDS-DAO Q13 were broadly consistent across subgroups. View on PubMed →

Vyleesi (bremelanotide injection), FDA Prescribing Information

FDA AccessData · 2019 Regulatory · label

Full prescribing information for Vyleesi: approved indication (HSDD in premenopausal women), contraindications (uncontrolled hypertension, known CV disease), dosing (1.75 mg SC, max 1/day, max 8/month) and full safety profile. View FDA label →

Vyleesi, FDA NDA 210557 Approval Package

FDA AccessData · 2019 Regulatory · approval package

The full FDA approval package for NDA 210557, including the multidisciplinary review of efficacy, safety and risk–benefit underlying the 2019 approval decision. View FDA approval package →

10 Frequently asked questions

Is PT-141 approved for men?

No. PT-141 (Vyleesi) is FDA-approved only for hypoactive sexual desire disorder in premenopausal women. Use in men is off-label. Earlier phase 2 trials of intranasal bremelanotide for male erectile dysfunction were discontinued in the 2000s because of dose-related blood pressure increases, and no large modern phase 3 male trial has been completed.

How is PT-141 different from Viagra?

They work in different places on different things. Sildenafil (Viagra) is a PDE-5 inhibitor that acts peripherally on blood vessels in the penis to enable an erection in response to existing arousal. PT-141 acts centrally, on melanocortin receptors in the brain, to increase subjective sexual desire. They target different problems: PT-141 is for "I do not feel like it"; Viagra is for "the equipment will not cooperate".

What does PT-141 actually feel like?

In trials, the effect is best described as an increase in desire and interest, not a guaranteed physical response. Modest in size on a population level, the average improvement over placebo on the FSFI-Desire scale was roughly 0.35 points, and bundled with a high rate of nausea (~40%) and transient blood-pressure increases. It is not a switch.

Why did so many people drop out of the trials?

Nausea, mostly. About 40% of RECONNECT participants reported nausea, and around 18% on active drug discontinued because of side effects (versus 2% on placebo). The effect size is also modest, so some patients judged the benefit was not worth the side effects.

Is "PT-141" from a research-chemical site the same as Vyleesi?

No, you cannot assume so. Vyleesi is a specific FDA-reviewed product with verified identity, purity and dose in a single-use auto-injector. "PT-141" sold by peptide vendors is research-chemical material with no equivalent QC; you are trusting the seller. The cardiovascular and pigmentation risks on the FDA label apply at least as much to the unregulated version.

Can I get PT-141 in the UK?

Not as a licensed medicine. The MHRA has not approved bremelanotide and there is no compliant pharmacy supply in the UK. Material sold online as "PT-141" is research-chemical only and not legal to supply for human use. If sexual desire is a concern, the right step is a GP appointment to discuss licensed options.