Peptides for sexual health are mostly compounds that act on brain pathways for desire and arousal rather than on blood flow. The best studied is PT-141 (bremelanotide), which the FDA approved in 2019 as Vyleesi for low sexual desire in premenopausal women.[2][1] Kisspeptin is still experimental, and Melanotan II, the tanning peptide PT-141 was developed from, has never been approved.[10]
This overview covers what these peptides are, how they work, how they compare with erectile dysfunction pills and with Addyi, and what is known about safety and legal status.
What are peptides for sexual health?
Sexual function depends on several systems: desire and arousal signals in the brain, hormones such as testosterone, and blood flow to the genitals. Most well-known prescription drugs target the last of these. The peptides in this category instead act on the first two:
- Melanocortin peptides (PT-141 and Melanotan II) copy alpha-MSH, a natural hormone that acts on melanocortin receptors in the brain and skin.[10]
- Kisspeptin switches on the reproductive hormone chain, raising LH and, in men, testosterone, and also appears to act on brain areas linked to sexual and emotional processing.[14][15]
They are different from hormone therapy, which we cover under hormonal peptides.
Browse all sexual health peptides
- PT-141 Melanocortin receptor agonist (Vyleesi)
- Melanotan II Synthetic alpha-MSH analog used for tanning
- Kisspeptin-10 Kisspeptin receptor agonist
- hMG Fertility hormone with FSH and LH activity (Menopur)
- hCG Pregnancy hormone with LH-like activity (Novarel, Pregnyl)
- Oxytocin Pituitary hormone (Pitocin) also used as a nasal spray
How sexual health peptides work
PT-141. Bremelanotide activates several melanocortin receptor subtypes. The Vyleesi label says the way it improves low sexual desire is not known.[1] In two phase 3 RECONNECT trials in 1,267 premenopausal women, it improved desire scores and reduced distress more than placebo, though the differences were modest.[3] An independent re-analysis argued the benefits are small and some outcome measures questionable.[4]
Melanotan II. Created at the University of Arizona as a tanning agent, it caused unexpected erections in early studies, which led to PT-141.[10] In small crossover trials, it produced erections in 8 of 10 men with psychological erectile dysfunction,[11] and after 12 of 19 injections versus 1 of 21 placebo injections in men with physical causes, with severe nausea after 4 injections.[12]
Kisspeptin. Kisspeptin-10, the short form sold online, raised LH within 30 minutes in healthy men, and longer infusions raised testosterone.[14] The sexual-function research used the longer natural form, kisspeptin-54, given by IV infusion. In healthy men, it boosted activity in brain reward and emotion areas when viewing sexual images.[15] In 32 men with low sexual desire, it changed sexual brain activity and increased erection response to erotic videos by up to 56% versus placebo,[16] and in 32 women with low desire, it altered brain responses to erotic videos.[17] Whether kisspeptin-10 injections would do the same has not been studied.
Peptides vs ED medications
Erectile dysfunction pills and melanocortin peptides work at different points.
| PDE5 inhibitors (e.g., Viagra) | PT-141 (Vyleesi) | |
|---|---|---|
| Where it acts | Blood vessels in the penis | Melanocortin receptors, mainly in the brain |
| Approved for | Erectile dysfunction in men | Low sexual desire in premenopausal women |
| Needs sexual stimulation | Yes, per the label | Not addressed on the label (it treats low desire, not erections); one early company study saw erections in healthy men without erotic videos[6] |
| How it is taken | Pill | Injection under the skin |
The Viagra label explains that sexual stimulation releases nitric oxide in the penis, which raises a chemical messenger (cGMP) that relaxes smooth muscle and lets blood flow in. Sildenafil blocks PDE5, the enzyme that breaks that messenger down, and, at recommended doses, has no effect without sexual stimulation.[8] It must not be combined with nitrate heart medicines.[8]
PT-141 instead acts on melanocortin receptors, including MC3R and MC4R, which are found mainly in the brain and spinal cord; in rats it activated nerve cells in the hypothalamus.[5] Because it works differently, early company studies tested it in men who had not responded to Viagra and found injected PT-141 produced erections,[6] and a low nasal dose combined with sildenafil gave a stronger response than sildenafil alone in a small study.[7] Even so, the Vyleesi label says it is not for men or for enhancing sexual performance.[1]
Vyleesi vs Addyi
Addyi (flibanserin) is the other FDA-approved drug for low sexual desire in women. Both labels say their mechanism in low desire is unknown.[1][9]
| Vyleesi (bremelanotide) | Addyi (flibanserin) | |
|---|---|---|
| Form | As-needed injection, at least 45 minutes before sex | 100 mg pill every night at bedtime |
| Approved for | Premenopausal women with acquired, generalized low desire | Women under 65 with acquired, generalized low desire |
| Boxed warning | None | Severe low blood pressure and fainting with alcohol taken close in time, moderate or strong CYP3A4 inhibitors, or liver impairment |
The two have not been compared head to head.[1][9]
Sexual health peptides for women and for men
The evidence differs sharply by sex, so it helps to look at each separately.
Women. PT-141 is the only peptide approved for a sexual problem, and only for premenopausal women whose low desire is acquired, generalized and distressing, and not caused by another condition, relationship problems or a medicine.[1] In the RECONNECT trials, desire scores improved by 0.30 to 0.42 points more than with placebo.[3] In a 52-week open-label extension, the benefits held and no new safety signals appeared.[21] The label advises stopping after 8 weeks if there is no improvement, and 18% of women in trials stopped because of side effects, versus 2% on placebo.[1] Kisspeptin research in women is limited to short brain-imaging studies with kisspeptin-54.[17]
Men. No peptide is approved for any sexual problem in men. The human data come from small studies of PT-141 (run by its developer) and Melanotan II (at the University of Arizona) from the late 1990s and 2000s,[6][12] plus the kisspeptin-54 study in men with low desire.[16] Erectile dysfunction has approved oral treatments, such as sildenafil, with labeled dosing and safety warnings.[8] The Vyleesi label states that it is not indicated for men.[1]
Safety, legality and sports rules
- PT-141: on the Vyleesi label, nausea affected 40% of users versus 1.3% on placebo. Blood pressure rises for several hours after each dose, so it is not for people with uncontrolled high blood pressure or heart disease. The label allows no more than one dose in 24 hours and eight per month.[1]
- Melanotan II: never approved anywhere. A dermatology review described melanoma, new or changing moles and other harms in users of unregulated products, while noting a direct cause has not been proven.[13] FDA treats it as an unapproved new drug, and one US seller was convicted of a felony.[19] Its compounding nomination was withdrawn.[18]
- Kisspeptin-10: FDA lists it among bulk substances that may present significant safety risks for compounding (503A category 2).[18]
- Sport: WADA’s 2026 list bans kisspeptin and its agonists in male athletes. Bremelanotide is not named. Melanotan II is not named either, but as a substance with no regulatory approval it would, in our reading, fall under S0 (non-approved substances), prohibited at all times.[20]
Related comparisons and guides
- Our PT-141 profile covers Vyleesi dosing, use in men and nasal sprays in detail.
- The kisspeptin-10 profile separates kisspeptin-10 from kisspeptin-54.
- For vial math, see how to reconstitute peptides and the peptide calculator.
Related categories: skin peptides, where Melanotan II’s tanning use is covered, and hormonal peptides.
