Peptide Education
What Is PT-141 (Bremelanotide)? The Libido Peptide Explained
PT-141 is one of the few popular research peptides that is also an FDA-approved drug. Sold as Vyleesi, bremelanotide was approved in 2019 to treat low sexual desire in premenopausal women. Unlike Viagra-type drugs, it works in the brain rather than on blood flow. This guide covers what PT-141 is, how it works, what the trials found, side effects, and what the approval does and does not cover.
Reviewed for accuracy · Last reviewed October 19, 2026
What Is PT-141?
PT-141 is the research code for bremelanotide, a synthetic seven-amino-acid cyclic peptide. It was developed from Melanotan II, an experimental tanning peptide created at the University of Arizona. Researchers noticed that Melanotan II increased sexual arousal, and bremelanotide was refined from it to focus on that effect.
It was developed by Palatin Technologies, and the FDA approved it as Vyleesi in June 2019 for hypoactive sexual desire disorder (HSDD) in premenopausal women. It is the second FDA-approved treatment for low desire in women, after flibanserin (Addyi).
How Does PT-141 Work?
PT-141 activates melanocortin receptors, mainly MC4R and MC3R, in the hypothalamus and other brain areas involved in sexual motivation. Activating these receptors is thought to increase dopamine release in reward pathways linked to desire.
- Brain, not blood flow: PDE5 inhibitors such as sildenafil work by increasing blood flow to the genitals. PT-141 works on desire and arousal signals in the brain.
- On-demand use: in its approved form, it is used as needed before sexual activity, not daily.
- Melanocortin family: the same receptor family controls appetite, pigmentation and inflammation, which explains some of its side effects.
What Does the Research Show?
The RECONNECT trials. Approval was based on two phase 3 trials, together called RECONNECT, that enrolled about 1,250 premenopausal women with HSDD for 24 weeks. Compared with placebo, women using bremelanotide reported a statistically significant increase in sexual desire and a reduction in distress about low desire.
Size of the effect. The improvements were real but modest. Bremelanotide did not significantly increase the number of satisfying sexual events compared with placebo, which was one of the trials’ secondary measures.
Men. Earlier studies tested PT-141 in men with erectile dysfunction, including men who did not respond well to sildenafil, and showed erectile responses. It is not FDA-approved for men, and no large phase 3 trials in men have been completed.
| Area | What studies show | Evidence type |
|---|---|---|
| Low desire in premenopausal women | Modest increase in desire, less distress | Two phase 3 RCTs (FDA-approved) |
| Satisfying sexual events | No significant difference vs placebo | Phase 3 RCTs |
| Erectile dysfunction in men | Erectile responses reported | Phase 2 studies |
| Postmenopausal women | Not approved for this group | Limited |
PT-141 Side Effects
Because Vyleesi is an approved drug, its side effects are well documented. In the RECONNECT trials, the most common were:
- Nausea: about 40% of users, the most common reason people stopped
- Flushing: about 20%
- Headache and injection-site reactions
- Temporary rise in blood pressure and drop in heart rate after each use
- Darkening of skin (focal hyperpigmentation) on the face, gums or breasts in about 1% of users, which did not always fade
The label advises against use in people with uncontrolled high blood pressure or known heart disease. It also limits how often it can be used per day and per month because of the blood pressure and pigmentation effects.
Is PT-141 FDA-Approved?
Yes, as Vyleesi, for one specific use. The approval covers acquired, generalized low sexual desire in premenopausal women that is not caused by a medical or psychiatric condition, relationship problems, or medication. It is a prescription drug.
Products labeled “PT-141” from research suppliers are not Vyleesi. They are sold for laboratory research only, are not made under drug manufacturing standards, and are not intended for human use.
PT-141 vs Other Sexual Health Options
| Option | How it works | FDA status |
|---|---|---|
| PT-141 (Vyleesi) | Melanocortin receptors in the brain; on-demand | Approved for HSDD in premenopausal women |
| Flibanserin (Addyi) | Serotonin and dopamine balance; daily pill | Approved for HSDD in premenopausal women |
| Sildenafil, tadalafil | PDE5 inhibition; increases genital blood flow | Approved for erectile dysfunction |
| Melanotan II | Non-selective melanocortin agonist | Not approved |
| Kisspeptin | Upstream reproductive hormone signal | Investigational |
PT-141 vs Melanotan II. The two are closely related, but bremelanotide was refined to have less effect on skin pigmentation and went through full clinical testing. Melanotan II never did and carries additional safety concerns. See our Melanotan II guide.
PT-141 vs flibanserin. Flibanserin is a daily pill with alcohol restrictions, while bremelanotide is used only when needed. Neither works for everyone, and both produce modest average improvements.
Buying Research-Grade PT-141: What to Check
Products sold as PT-141 by research suppliers are laboratory chemicals, not medicines. They are not made under drug manufacturing rules, so quality varies a lot between vendors. If you are evaluating a PT-141 supplier for lab research, these are the checks that matter:
- Batch-specific COA: the certificate should match the lot number on your vial, not a generic sample.
- Independent lab: testing should come from a named third-party lab, ideally with a way to verify the report online.
- Identity, not just purity: HPLC purity alone does not confirm the right molecule; look for mass spectrometry (MS) identity confirmation.
- Endotoxin and sterility results: these matter for any injectable research material.
- Correct fill amount: the measured content should be close to the labeled milligrams.
Our Trusted Sources page lists vendors we track, with current community codes. Our guide to reading a certificate of analysis explains each line of a COA.
Key Takeaways
- PT-141 is bremelanotide, a melanocortin peptide derived from Melanotan II.
- It is FDA-approved as Vyleesi for low sexual desire in premenopausal women.
- It works on desire signals in the brain, not on blood flow.
- Trials showed modest improvements; nausea affected about 40% of users.
- It is not approved for men, and research-grade PT-141 is not Vyleesi.
Frequently Asked Questions
What is PT-141?
PT-141 is bremelanotide, a synthetic peptide that activates melanocortin receptors in the brain to increase sexual desire. It is sold as the FDA-approved drug Vyleesi.
Is PT-141 FDA-approved?
Yes, as Vyleesi, approved in 2019 for low sexual desire (HSDD) in premenopausal women. It is not approved for men or for other uses.
Does PT-141 work for men?
Early studies showed erectile responses in men, including some who did not respond to sildenafil, but it has not completed phase 3 trials in men and is not approved for them.
What are the side effects of PT-141?
The most common are nausea (about 40%), flushing and headache. It also temporarily raises blood pressure and can darken patches of skin.
Is PT-141 the same as Melanotan II?
No. PT-141 was developed from Melanotan II but refined to focus on sexual function, and it went through full clinical trials. Melanotan II is not approved.
Sources
- Obstetrics & Gynecology – Kingsberg et al. (2019), Bremelanotide for the treatment of hypoactive sexual desire disorder: two randomized phase 3 trials
- FDA – Vyleesi (bremelanotide injection) prescribing information (2019)
- FDA – FDA approves new treatment for hypoactive sexual desire disorder in premenopausal women (June 2019)
- Diamond et al. (2004) – Bremelanotide in men with erectile dysfunction
MLCR SCTY provides educational information, not medical or legal advice. Research-use-only products are not intended for human consumption.