Kisspeptin has real human trials. The best-known ones used a different molecule.

Why this note exists

Kisspeptin is unusual in pepmg’s index: a compound whose vendor copy is under-stated relative to the literature in one respect and badly over-stated in another. There really are randomized, placebo-controlled human trials. They just did not test what is in the vial, by the route it is sold for, for a length of time that would answer a user’s question.

In the index generated on August 12, 2026, 68 of 112 vendors carried a kisspeptin listing — 87 listings in total, twentieth by vendor coverage across the registry.[19] Where a size is stated, 10 mg is by far the most common (57 listings), then 5 mg (16).[19] Every published human protocol below is written in nanomoles per kilogram per hour, or nanomoles per hour, delivered by infusion or as a weight-based single injection. There is no published milligram-per-vial equivalent, and this note does not calculate one.

A note on what kind of evidence this is: everything in the next four sections is human data, and it is labeled with its design and its participant count. There is one animal section, and it is marked as such. Where a study is open-label or has no comparator arm, this note says so rather than leaning on the word “randomized.”

The new paper

Twelve days, fifteen men, and a pump

This is the study that closes part of the gap, and it is worth reading precisely. Published in the European Journal of Endocrinology on August 3, 2026, it was a randomized, single-blinded, placebo-controlled study in healthy men, run as three linked protocols. Fifteen men were recruited across them (n = 7, n = 4 and n = 7) and 12 men served as controls.[1]

Participant counts and protocols as reported by the authors. Twelve further men served as controls.[1]

The middle result is the interesting one, and it runs against the intuition a product page would give you. Five days of uninterrupted kisspeptin-10 did not keep gonadotropins up. The pattern that worked was intermittent: over 12 days of daily 8-hour infusions, mean luteinizing hormone rose by 1.68 ± 0.25 on day 1 and was still up by 1.14 ± 0.33 on day 12, against −0.16 ± 0.19 on vehicle.[1] After the twelve days, a bolus still produced a gonadotropin rise, which the authors read as the receptor remaining functional.[1]

Two limits belong in the same breath. The endpoints were hormone concentrations in healthy volunteers — not fertility, not symptoms, not body composition, not sexual function. And the delivery was an infusion protocol at a set rate per hour, which is not the same thing as a self-administered daily injection. The authors’ own stated conclusion is that the data “can inform development of chronic kisspeptin administration protocols for the treatment of reproductive disorders.”[1] That is a sentence about future development.

Two names

Kisspeptin-10 and kisspeptin-54 are not interchangeable

Both fragments come from the same precursor protein, and both activate the same receptor. But they are different peptides, and the human literature splits along that line more sharply than the market does. Kisspeptin-54 is described as the major circulating isoform in humans and is the molecule used in the IVF trigger trials and in the psychosexual and anxiety studies.[2][5][7] Kisspeptin-10 is the shorter fragment; the 2011 study that first characterized it in men called it “the minimal kisspeptin sequence with full intrinsic bioactivity” and noted it had not been studied in man before that point.[8]

The naming in the market makes this harder to see, not easier. Among the listings in pepmg’s index are product names such as “KISSPEPTIN-10 10 MG,” where the same numeral does two different jobs — one identifying a 10-amino-acid fragment, the other a vial’s milligram content.[19] pepmg’s own registry groups these listings under a single Kisspeptin entry with “kisspeptin-10” as an alias, which is the honest thing to do for price comparison and a poor guide to what a study tested.

None of this makes kisspeptin-10 a fake. It is a real, well-characterized peptide with human pharmacology going back to 2011. It is simply not the molecule behind most of the headlines.

Evidence ledger

The human record, by design and size

Participant counts as reported in each publication. Counts are of separate studies over a decade, not one program.

Zooming out to the registry gives the same picture. A ClinicalTrials.gov search on August 13, 2026 returned 25 registered interventional studies of kisspeptin, most of them phase 1 or phase 2 physiology work; the largest listed enrollment is 256 participants.[17] Three entries carry a phase 3 label, and they enrolled 30, 15 and 14 people — a reminder that the phase field in a registry describes how an academic sponsor filled in a form, not the existence of a late-stage program.[15][17]

What the IVF trials do, and do not, establish

These are the strongest clinical-outcome data kisspeptin has, and they deserve to be stated at full strength before the caveats. In 2014, 53 women undergoing IVF received a single subcutaneous injection of kisspeptin-54 at one of four weight-based doses to trigger egg maturation. Eggs were retrieved 36 hours later. Fertilization and embryo transfer went ahead in 92% of patients (49 of 53); biochemical pregnancy was 40% (21 of 53) and clinical pregnancy 23% (12 of 53).[2]

A phase 2 study followed in 60 women at high risk of ovarian hyperstimulation syndrome, a serious complication of conventional triggers. Oocyte maturation occurred in 95% of women. Across all doses, per-transfer biochemical, clinical and live-birth rates were 63%, 53% and 45% (n = 51 transfers), and no woman developed moderate, severe or critical OHSS.[3] A 2017 phase 2 randomized trial then showed that a second dose ten hours after the first improved oocyte yield in the same high-risk population.[4]

Here is the part that gets dropped. The 2015 study was explicitly open-label and randomized between four doses of kisspeptin-54, not against the standard trigger it would have to beat.[3] A 95% maturation rate and a zero-OHSS count in 60 women are genuinely encouraging; they are not the same as a demonstration of superiority, and the absence of severe OHSS in a group that size cannot establish a rate. Eleven years after the first of these trials, kisspeptin is still not an approved trigger anywhere.[18]

The desire trials measured a brain scan

The two studies that put kisspeptin into consumer conversation are a matched pair from Imperial College London, and both are real randomized clinical trials. In the men’s trial, 37 heterosexual men with hypoactive sexual desire disorder were randomized and 32 completed; each attended two visits at least seven days apart for a 75-minute intravenous infusion of kisspeptin-54 at 1 nmol/kg/h or a rate-matched placebo, in balanced random order.[5] The women’s trial used the same infusion in premenopausal women with HSDD: 40 randomized, 32 completed.[6]

The primary outcome in both was blood-oxygen-level-dependent brain activity on functional MRI while viewing sexual stimuli. In the men, kisspeptin modulated activity across the sexual-processing network (mean absolute change, Cohen d = 0.81; P = .003). Secondary outcomes included penile tumescence in response to sexual stimuli, up to 56% greater than placebo (mean difference 0.28 units; P = .02), and a 0.63-point increase in self-reported happiness about sex (P = .02).[5] In the women, the reported effects were modulations of specific regional responses, with correlations between kisspeptin-enhanced hippocampal activity and baseline sexual distress.[6]

What neither trial did was treat anyone. A single infusion on a single day, with an imaging endpoint, is a mechanism study wearing the clothes of a clinical trial — which is exactly how the authors framed it, writing that the findings “lay the foundations for clinical applications.”[6] There is no published trial of kisspeptin given over weeks for sexual desire, and no measure of whether anything changed in anyone’s life outside the scanner.

One more from the same group belongs here because it is the kind of result that rarely gets quoted: a 2025 crossover study in 95 participants found that a biologically active intravenous dose of kisspeptin-54 did not alter state anxiety (P = .13), cortisol (P = .73), blood pressure or heart rate, despite robustly raising luteinizing hormone.[7] Animal work had pointed in contradictory directions; this is a clean human answer to a narrow question, and it is reassuring rather than promotional.

The animal data cuts both ways, and it is animal data

None of the work in this paragraph was done in people. The single dose record pepmg holds for kisspeptin is a 2022 rat study, and it is not a flattering one: prepubertal male Sprague-Dawley rats given kisspeptin-10 intraperitoneally twice daily showed reduced plasma testosterone at the 1 ng (P < .05) and 1 µg (P < .01) doses, along with ultrastructural degeneration and vacuolation of Leydig cells.[11] The authors’ conclusion was that chronic intermittent kisspeptin-10 had a dose-dependent degenerative effect in that model.[11]

It would be as wrong to read that as “kisspeptin damages testicles in men” as it is to read the human infusion studies as “kisspeptin raises testosterone safely.” The rat study used a different species at a prepubertal age, a different route, and doses that cannot be lined up against the human protocols. What it does establish is that chronic exposure has been reported to move testosterone in opposite directions in different models — which is a reason for the twelve-day human study to exist, and a reason not to assume its result generalizes past twelve days.

Not approved, and the industry route is an analogue

Kisspeptin is not an approved medicine in the United States, the European Union or the United Kingdom, in either isoform. A Drugs@FDA search on August 13, 2026 returned no approved kisspeptin product.[18]

Where commercial development has gone is instructive. MVT-602, a kisspeptin receptor agonist rather than the native peptide, was tested in two randomized, placebo-controlled dose-finding trials — 24 healthy premenopausal women in the phase 1 and 75 in the phase 2a, each receiving a single subcutaneous microgram-scale dose.[10] A separate receptor agonist, TAK-448, has two registry entries in men that were terminated.[16] Meanwhile the academic groups are working on delivery: a 2025 study reported that intranasal kisspeptin-54 raised luteinizing hormone in healthy men, healthy women and patients with hypothalamic amenorrhoea, explicitly because intravenous and subcutaneous routes “markedly limit patient acceptability.”[9] That paper also includes mouse work, which it labels as such.

Two registry entries show where chronic dosing is actually being studied in patients rather than volunteers: a completed phase 2 of prolonged pulsatile kisspeptin in hypogonadotropic hypogonadism (18 enrolled), and a phase 1 study whose title says the quiet part out loud — Dampening the Reproductive Axis With Continuous Kisspeptin (8 enrolled).[13][14]

Three things this note is not saying

First, it is not saying kisspeptin does nothing. The hormone effects are among the better-replicated findings for any compound in this index: bolus, infusion, subcutaneous, intranasal, 2011 through 2026, the gonadotropin response shows up.[8][9][1]

Second, it is not saying the trials were badly done. Small, careful mechanism studies are how a compound is supposed to be investigated. The problem is downstream, when a 75-minute infusion in a scanner becomes “clinically proven for libido” on a product page.

Third, it is not saying the safety record is bad. Several of these trials report no adverse effects at the doses used.[6][9] But a few dozen people dosed for hours, or fifteen men dosed for twelve days, cannot characterize the safety of repeated use. That is a statement about the size of the record, not about a known harm.

Questions people are asking