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Best Peptides for Sexual Health: What the Evidence Shows
Which peptides have evidence for low sexual desire? One approved drug, one with brain-scan studies, one with safety concerns, one that matched placebo.
The short answer
No peptide has been shown to be the best for sexual desire, and only one is FDA-approved for it, for one group of people. That peptide is bremelanotide (Vyleesi), approved for premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD). Its benefit in trials was modest, and it did not increase satisfying sexual events compared with placebo. For the other three we reviewed, kisspeptin, Melanotan II and oxytocin, we found no good evidence that they treat low desire.
We found no peptide that is FDA-approved to treat low desire or erectile dysfunction in men.
Low desire has many causes, including medicines, health conditions, mood and relationships. A clinician can sort those out first.
On this page
Peptides sold for libido range from a prescription drug with a narrow label to research products that FDA has warned about. Here is how four of them compare, and why none can be called “best” outside one approved use.
The ranking, by strength of evidence
| Peptide | U.S. status | Strongest evidence |
|---|---|---|
| 1. Bremelanotide (PT-141) | Human trials | |
| 2. Kisspeptin | Limited human data |
How do we decide what is “best”?
“Best” means best evidence, not best marketing. We rank by the type of evidence first, then its quality and its result. A rank isn’t a recommendation. See how we rate peptides. For this goal, strong evidence would be a controlled trial in people with the condition that measured desire or satisfying sexual activity over weeks, not only a brain scan or a lab measurement. Only bremelanotide has controlled trials of that kind, and its result is modest.
| Bremelanotide | Kisspeptin | Melanotan II | Oxytocin | |
|---|---|---|---|---|
| FDA status | Approved as Vyleesi, for one use | Not approved. Kisspeptin-10, the form nominated for pharmacy compounding, is on FDA’s Category 2 list | Not approved. Nomination for compounding withdrawn; FDA lists safety risks | Approved as Pitocin for uses in labor, delivery and pregnancy loss only |
| Best human evidence for sexuality | Two phase 3 trials, 1,267 women | Small single-infusion trials of kisspeptin-54 that measured brain and lab responses | Tiny crossover trials in 10 to 20 men in the 1990s and 2000 | One randomized trial, 30 women: no better than placebo |
| Main limit | Modest, disputed effect; many dropped out | Not a treatment; the studied form is not the one sold | Safety reports; no large or safety trials | No effect beyond placebo |
Bremelanotide: what is approved, and for whom
Vyleesi is a prescription drug approved on June 21, 2019 (Drugs@FDA). Brand names are used here only to identify the labels. Its label (rev. 10/2026) says it is for premenopausal women with acquired, generalized HSDD, with low desire that causes marked distress or interpersonal difficulty and is not due to another medical or psychiatric condition, to the relationship or to a drug. It is “not indicated for the treatment of HSDD in postmenopausal women or in men” and “not indicated to enhance sexual performance.”
The effect is modest and its meaning is disputed. In the two phase 3 trials (Kingsberg 2019, 1,267 women, 24 weeks), desire scores rose about 0.35 points on a scale of 1.2 to 6 and distress fell about 0.33 points on a scale of 0 to 4. The label’s data show no difference in satisfying sexual events compared with placebo, and 18% stopped because of side effects vs 2% on placebo. A published critique questions whether the main measures are valid in HSDD.
Main safety points from the label: it is contraindicated with uncontrolled high blood pressure or known cardiovascular disease; about 40% had nausea; and it can darken patches of skin and gums, which did not clear in all patients. See our bremelanotide guide for the full evidence and risks.
“PT-141” sold as a research peptide is not Vyleesi. FDA has warned companies selling such products, with sales claims about libido, and calls them unapproved new drugs (FDA letter). The trial results above come from the approved product. We do not link to or recommend sellers.
Kisspeptin: small laboratory studies, and a different form from what is sold
Two forms exist, and they are not interchangeable.
- Kisspeptin-10 is the form nominated for pharmacy compounding. It is not FDA-approved and sits on FDA’s Category 2 list of substances that may pose significant safety risks for compounding, where it has been since 2023 and where it remains (also on the May 14, 2026 list). FDA cites a risk of immune reactions and impurities and says it lacks sufficient information to know whether the drug would cause harm. We found no studies of kisspeptin-10 in sexual function.
- Kisspeptin-54 is the form in the research trials. It was always given as a single 75-minute intravenous infusion in a research center.
| Study | Design | People | What it measured |
|---|---|---|---|
| Thurston 2022 | Randomized crossover, double-blind, placebo | 40 premenopausal women with HSDD (32 finished) | Primary: brain activity on fMRI in response to erotic stimuli and faces. Not desire in daily life |
| Mills 2023 | Randomized crossover, double-blind, placebo | 37 men with HSDD (32 finished) | Primary: fMRI. Secondary: penile tumescence measured in the laboratory up to 56% greater, and more “happiness about sex” (+0.63 points) |
| Comninos 2018 | Randomized crossover | Number not in the abstract; healthy men | Resting brain connectivity |
How to read these: they test one infusion and measure brain and laboratory responses, not desire or sexual activity at home over weeks. The authors describe the findings as potential and as laying a foundation. They are not evidence of a treatment, and nothing from kisspeptin-54 given intravenously carries over to a kisspeptin-10 product from a seller.
Melanotan II: not approved, with safety reports
Melanotan II is a different substance from bremelanotide, and its data should not be mixed with it.
- FDA’s safety statement. FDA lists Melanotan II as a nomination that was withdrawn, and says it carries a risk of immune reactions from aggregation or impurities. It says “published case reports discuss serious adverse events including melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxidrome and priapism” (FDA).
- Human trials are tiny and old. Crossover trials against placebo in men with erectile dysfunction enrolled 10 (Wessells 1998; Wessells 2000) and, in a group review, 20 men. Erections occurred with the drug; nausea and yawning were common, and nausea was sometimes severe. We found no large trials or safety trials.
- A case of toxicity: rhabdomyolysis and systemic toxicity were reported after an injection.
- Supply. A forensic analysis of seized samples found Melanotan II and bremelanotide alongside anabolic steroids. It shows only that the products circulate.
Oxytocin: approved for labor, and not better than placebo for sexual problems
Oxytocin (Pitocin) is FDA-approved for uses in labor, delivery and pregnancy loss, such as starting or strengthening contractions and controlling bleeding after birth (label). It is not approved for sexual function, and Pitocin is given by injection, not as a nasal spray.
In a randomized, double-blind crossover trial of 30 women, nasal oxytocin before intercourse (8 weeks per arm) improved sexual function no more than placebo. A follow-up of the women’s male partners found no difference between oxytocin and placebo in the men’s outcomes.
How big is the placebo effect?
In a meta-analysis of 8 randomized trials of treatments for female sexual dysfunction (1,723 women on placebo and 2,236 on treatment, including flibanserin, bremelanotide and nasal oxytocin), the placebo accounted for 67.7% of the treatment effect. That is one reason testimonials do not show that a product works.
What is not a peptide, and what does not exist?
- Flibanserin (Addyi) is an FDA-approved drug for low desire in women under 65, and it is not a peptide. We mention it for context only. Its label has a boxed warning about low blood pressure and fainting with alcohol and with certain interacting drugs (label). It is not indicated in men or to enhance performance.
- We found no FDA-approved peptide for low desire in men, or for erectile dysfunction. Approved non-peptide drugs exist for erectile dysfunction, but we did not review their labels.
- Postmenopausal women. Bremelanotide is not indicated, and we found no trial in that group.
- Kisspeptin-10 for libido or testosterone, “stacks” and blends. We found no evidence.
What are the risks?
- Bremelanotide: see the table in our bremelanotide guide. Contraindicated with uncontrolled high blood pressure or known cardiovascular disease.
- Kisspeptin-10: FDA says it lacks sufficient information to know whether the drug would cause harm.
- Melanotan II: the serious events reported to FDA above.
- Compounded and “research” products in general: compounded drugs are not FDA-approved, which means FDA does not review them for safety, effectiveness or quality before they reach patients.
Which claims are not supported?
- “A peptide that boosts libido in anyone.” Only one is approved, for one group, with a modest effect.
- “Kisspeptin boosts desire” or “increases erections.” The studies measured brain and lab responses after a single infusion.
- “Melanotan II is safe,” or “tans and boosts libido.” FDA lists serious adverse events.
- “Nasal oxytocin works for desire.” One small trial found it no better than placebo.
- “PT-141 online is the same as Vyleesi.” It is not the approved product.
What should you ask your doctor?
- What could be causing my low desire, including medicines, health conditions, mood, sleep, pain and my relationship?
- Does bremelanotide or another FDA-approved option fit my situation, and what do its label warnings mean for me?
- If someone suggests a research peptide, what is it, who made it, and what evidence supports it for me?
- What would tell us whether a treatment is working, and when should we stop?
We do not give doses, timing or preparation instructions, and we do not recommend products or sellers.
Frequently asked questions
What is the best peptide for low libido?
None can be called best. Only bremelanotide is FDA-approved for low desire, and only in premenopausal women with acquired, generalized HSDD, with a modest effect.
Is there a peptide for men?
We found no peptide that is FDA-approved to treat low desire or erectile dysfunction in men.
Does kisspeptin work for libido?
We found small single-infusion studies of one form that measured brain and laboratory responses, not a treatment. Kisspeptin-10, the form nominated for pharmacy compounding, is on FDA’s Category 2 list.
Is Melanotan II safe?
It is not approved. FDA says published case reports describe serious adverse events, including melanoma and priapism.
How much of the effect is placebo?
In one meta-analysis of trials of treatments for female sexual dysfunction, the placebo accounted for 67.7% of the treatment effect.
How did we rank them?
We rank by the type of evidence first, then its quality and its result. If no peptide has good evidence for a goal, we say so.
- Human trialsControlled trials in people, published in a journal, that tested a clinical outcome and showed a benefit. The strongest kind of evidence we report.
- Limited human dataSmall, short or inconclusive human studies, including observational studies, uncontrolled trials and controlled trials that did not show a clinical benefit.
- Animal studiesResults in animals often don’t carry over to people.
- Lab studiesCells or tissue in a dish. An early signal, not an answer.
From Best Peptides Today
Sources we checked
- Vyleesi prescribing information (FDA, rev. 10/2026)FDA. Accessed .
- Drugs@FDA: NDA 210557 (Vyleesi)FDA. Accessed .
- Kingsberg 2019: RECONNECT phase 3 trials of bremelanotide, Obstet Gynecol (PubMed)PubMed. Accessed .
- Spielmans and Ellefson: critique of the bremelanotide trials, J Sex Res (PubMed)PubMed. Accessed .
- FDA warning letter, Aug. 24, 2026 (peptide product labeled PT-141)FDA. Accessed .
- FDA: bulk drug substances that may present significant safety risksFDA. Accessed .
- FDA 503A Category 1 list (updated May 14, 2026)FDA. Accessed .
- Thurston 2022: kisspeptin in premenopausal women with HSDD, JAMA Netw Open (PubMed)PubMed. Accessed .
- Mills 2023: kisspeptin in men with HSDD, JAMA Netw Open (PubMed)PubMed. Accessed .
- Comninos 2018: kisspeptin and brain connectivity in healthy men, JCI Insight (PubMed)PubMed. Accessed .
- Wessells 1998: Melanotan II in men with erectile dysfunction (PubMed)PubMed. Accessed .
- Wessells 2000: Melanotan II in men with erectile dysfunction, Urology (PubMed)PubMed. Accessed .
- Case report: rhabdomyolysis and systemic toxicity after Melanotan II (PubMed)PubMed. Accessed .
- Forensic analysis of seized samples including bremelanotide and Melanotan II (PubMed)PubMed. Accessed .
- Pitocin (oxytocin) prescribing information (DailyMed)FDA. Accessed .
- Muin 2015: nasal oxytocin for sexual function in women, Fertil Steril (PubMed)PubMed. Accessed .
- Muin 2017: oxytocin in couples (PubMed)PubMed. Accessed .
- Weinberger 2018: placebo response in female sexual dysfunction trials, meta-analysis, Obstet Gynecol (PubMed)PubMed. Accessed .
- Addyi (flibanserin) prescribing information (DailyMed)FDA. Accessed .
- FDA: compounding laws and policiesFDA. Accessed .
- Review of the Melanotan II erectile dysfunction trials (PubMed)PubMed. Accessed .
Written and maintained by the Best Peptides For Editorial Team. How we rate evidence.