Sexual health entered the peptide conversation through two compounds with entirely different mechanisms and entirely different evidence bases. PT-141 (bremelanotide) is an FDA-approved melanocortin agonist for hypoactive sexual desire disorder in premenopausal women. HCG (human chorionic gonadotropin) has been used clinically since the 1930s, is FDA-approved for hypogonadotropic hypogonadism in men, and is the most established agent for preserving testicular function during testosterone replacement therapy. The fact that both fall under "sexual health peptides" obscures how different the cases for each actually look.
Key takeaways#
- PT-141 (bremelanotide) is FDA-approved for hypoactive sexual desire disorder in premenopausal women under the brand name Vyleesi. It acts on melanocortin receptors centrally, not on the vascular pathway that PDE5 inhibitors target.
- HCG is a long-established clinical agent, FDA-approved for hypogonadotropic hypogonadism in men. The AUA guideline lists it, with SERMs and aromatase inhibitors, as an option for men with testosterone deficiency who want to maintain fertility, and it is the only one of those three approved for use in men. Since March 2020 the FDA regulates hCG as a biologic, which takes it outside the 503A and 503B compounding exemptions.
- The two compounds address different problems. PT-141 targets desire and arousal. HCG targets the hormonal infrastructure that supports endogenous testosterone production. The decision between them is not a comparison; it is a different question entirely.
- Both compounds are FDA-approved with established side-effect profiles: bremelanotide on two Phase 3 trials, hCG on decades of clinical use. This cluster has more clinical-grade evidence per molecule than most of the peptide catalogue.
- Klarovel does not sell, source, or fulfil peptides. The catalogue here is the protocol and education layer.
Why sexual health is a clean peptide-research case#
Most peptide categories live in tension between mechanism and evidence. The longevity catalogue has strong mechanisms with thin human data. The healing catalogue has decades of off-label use without large randomised trials. Sexual health is different. Both PT-141 and HCG arrived in the clinic through standard pharmaceutical development. PT-141 came from a melanocortin-agonist discovery programme aimed at sexual dysfunction. HCG was characterised as a placental hormone in the 1920s, identified as biologically active for testicular stimulation in the 1930s, and entered clinical use shortly after.
What this means for a reader: the credibility floor in this cluster is higher than in most peptide categories. The marketing problem is the opposite. Compounds with this much published data become targets for off-label expansion claims that the trials do not actually support. The pillar's job is to separate what each compound actually does from what it gets promoted for.
PT-141 (bremelanotide): the central melanocortin route#
PT-141 is a synthetic cyclic heptapeptide analogue of alpha-MSH. It activates melanocortin receptors, primarily MC3R and MC4R, with effects in the central nervous system that influence sexual desire and arousal. The drug was originally developed at Palatin Technologies as a follow-on from earlier melanocortin work (the same chemistry family that includes melanotan compounds, though PT-141 is a separate molecule with a different target profile).
The clinical pathway is straightforward. FDA approval came through two Phase 3 trials in premenopausal women with hypoactive sexual desire disorder. The primary endpoints (sexual desire scores and reduction in distress) hit. The trade-off is a side-effect profile that includes nausea (the most common, in about 40 percent of patients, mostly after the first dose), facial flushing, and headache. Blood pressure rises transiently after each dose, which is why the label contraindicates use in patients with uncontrolled hypertension or known cardiovascular disease.
Off-label use in men is where the evidence gets thinner. Research has shown PT-141 produces signals of activity in male erectile dysfunction in earlier-phase trials, but no FDA approval has been granted for the male indication. The biology suggests the mechanism should work in men too, but the regulatory pathway never delivered. The PT-141 complete guide walks through both the approved indication and the off-label male research in detail.
A note on the pill form claim that surfaces online: the approved product is a subcutaneous autoinjector. An intranasal formulation was used in earlier trials (the Vyleesi label still cites intranasal studies) before development moved to subcutaneous dosing. Any "PT-141 pill" sold online is by definition not the FDA-approved product and has no published bioavailability data.
HCG for men: fertility, TRT support, and the testosterone question#
HCG (human chorionic gonadotropin) is structurally similar to luteinising hormone. When administered to men, it binds the LH receptors on Leydig cells in the testes and triggers testosterone production at the source rather than supplying exogenous testosterone. This mechanism is what makes it the most established adjunct for men on testosterone replacement therapy who want to preserve testicular size and spermatogenesis, although that use is off-label. For a broader view of how peptides are used across other goals in men's health, see peptides for men.
The clinical use case has three branches:
The first is fertility preservation during TRT. Exogenous testosterone suppresses the hypothalamic-pituitary-gonadal axis through negative feedback. The testes stop producing endogenous testosterone, atrophy, and spermatogenesis halts. HCG bypasses the suppression by acting downstream of the hypothalamus, directly at the testes. Compounds that act at the top of that axis instead, kisspeptin among them, are covered in the guide to peptides for testosterone. In a retrospective series of 26 men on TRT plus 500 IU hCG every other day, none became azoospermic and semen parameters did not change over follow-up (Hsieh et al., J Urol 2013); TRT alone causes azoospermia in a substantial share of men.
The second is primary male infertility, particularly in men with hypogonadotropic hypogonadism, where the upstream signalling is broken but the testes themselves can respond. HCG combined with FSH (or hMG) has been shown to restore fertility in this population in multiple published series.
The third, more controversial, is post-cycle therapy for anabolic steroid use. The mechanism is the same as TRT-adjunct use. The clinical evidence is thinner. The HCG for men guide covers the protocol variations and the published data per use case.
The regulatory picture: HCG is FDA-approved for prepubertal cryptorchidism, selected cases of hypogonadotropic hypogonadism in men, and ovulation induction, and is dispensed by prescription (Novarel label). On March 23, 2020 approved hCG products were deemed biologics licenses, and biologics are not eligible for the 503A and 503B compounding exemptions, so compounded hCG is no longer a lawful route (FDA). Off-label use during TRT is common in private practice and within the prescriber's discretion. In Norway hCG is a prescription medicine; Felleskatalogen currently lists Gonasi (urinary hCG) and Ovitrelle (recombinant hCG, authorized for women's fertility treatment).
What the cluster does not include#
A pillar in this category invites the question of what else belongs. Two compounds get raised regularly:
Kisspeptin is the upstream signalling peptide that activates GnRH neurons and triggers the LH surge. Phase 1 and Phase 2 trials have studied it in hypothalamic amenorrhea and in IVF cycle support. Sexual-function work is earlier but real: in a randomized crossover trial of 32 men with hypoactive sexual desire disorder, a 75-minute kisspeptin-54 infusion changed sexual-processing brain activity and increased penile tumescence to sexual stimuli by up to 56% versus placebo (Mills et al., JAMA Netw Open 2023). That is preliminary evidence from a single-dose laboratory study, not a treatment trial. As of 2026 kisspeptin has no FDA approval for any use, and kisspeptin-10 sits in Category 2 of the FDA's 503A compounding list, so it is treated as a research compound in this cluster.
Oxytocin is the obvious other candidate. Published research on intranasal oxytocin in sexual-function endpoints is mixed and methodologically contested. Klarovel's editorial position on oxytocin is that the literature is not strong enough to anchor a pillar position, and the off-label sourcing risk is high enough that we do not recommend the compound in protocol output.
Protocol logic when both compounds enter the picture#
The two compounds rarely overlap in a single protocol. PT-141 is episodic, used on demand for a specific event. HCG is a maintenance protocol, administered two or three times weekly during the months it is needed. The decision between them is driven by the actual problem:
If the problem is desire or arousal, PT-141 is the on-label compound. The female indication has Phase 3 data; the male use is off-label but mechanistically supported. Which compounds were actually studied in female participants is sorted out in the guide to peptides for women.
If the problem is fertility, testicular function, or hormonal support during TRT, HCG is the long-established option. The female use case is different (HCG plays a role in IVF protocols and pregnancy support, not in sexual health per se).
If the problem is broader, including erectile function, mood, energy, body composition, the testosterone story matters more than the peptide story. HCG fits inside a TRT protocol; PT-141 does not. The peptides vs TRT comparison covers the TRT versus peptide-stack decision rule in more depth.
Where this cluster goes next#
Two compounds is a thin pillar by intent. Both have substantial individual evidence, but the cluster will benefit from additional spokes covering the broader sexual-health peptide question: kisspeptin once its trial pipeline matures, melanocortin chemistry in general, and the testosterone-versus-peptide stack decision in more depth.
For now, the protocol-side conversation starts at the Klarovel questionnaire. Health profile + goals get matched to the compound and evidence level that fits, rather than to whatever has the loudest marketing.
- HCG for Men: Fertility, TRT and Testicular Function Guide: How hCG works in men, what the evidence shows for fertility, testicular size and hypogonadism, and how researchers think about dose, timing and safety.
- Peptides for Men: What Works by Goal and Evidence Stage: Men search peptides for seven goals: muscle, fat loss, libido, hormones, recovery, hair, longevity.
- Peptides for Testosterone: Which Axis Actually Works: Most peptides for testosterone act on the growth hormone axis and never touch LH.
- Peptides for Women: What the Female Trial Data Shows: Most peptide trials enrolled mostly men.
- PT-141 Guide: Mechanism, Evidence, and Honest Limits: PT-141 (bremelanotide) acts on brain melanocortin receptors, not blood vessels.
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