Kisspeptin-54
Kisspeptin-54, the 54 residue KISS1 gene product
Written by Aaron CuhaReviewed Sep 2026
Also known as: Metastin, KP-54, Kisspeptin-54 (68-121)
In plain English, from Aaron
This is how I would explain it to a friend. The evidence, with the numbers, is further down the page.
Kisspeptin-54 tells your brain to release the hormone that starts the whole sex hormone chain. One shot causes a surge of LH, the signal that tells the ovaries to release an egg or the testes to make testosterone. It is the full length version of a hormone your body already makes. It is not approved anywhere. The best evidence for it is in IVF clinics, and it is very good evidence for one narrow job.
What people take it for
- Raising testosterone the natural way in men.
- More sex drive.
- Fertility, either in IVF or after a steroid cycle.
- Less anxiety and a better mood.
What the trials actually showed
The IVF work is real and randomised. Doctors in London gave one shot to 60 women who were at high risk of a dangerous over response to IVF drugs. It matured the eggs in 95 percent of them. Across 51 embryo transfers, 63 percent got pregnant on a blood test, 53 percent had a pregnancy on a scan, and 45 percent had a live baby. Not one woman got a moderate or severe over response. A second trial of 62 women found a second shot ten hours later gave more eggs. That is the good news, and it is only about IVF. Now the other side. When women got it over and over, the response faded. That was the title of the study. A randomised trial in 2025 gave it to people and measured anxiety. Hormones went up. Anxiety did not change. A 2025 study showed a nose spray version also raises the hormones. And in adult male rats, daily shots under the skin damaged the testes. That is rats, not men, but it is the exact way men use it. No trial has ever measured sex drive, muscle, memory or focus with this peptide.
What people report
Reports, not trial results
The good
- A bump in sex drive for a day or so after a shot.
- Some men report higher LH or testosterone on blood work after a short run.
- A better mood on the day of the dose.
The bad
- Hot flushes and a red face after a shot.
- Headaches and nausea.
- It fades. Users say daily shots stop doing anything after a few weeks. The trial record agrees with them.
- Nobody has checked what daily shots do to the testes in men. In rats it was damage.
- Grey market vials of unknown strength.
Where these come from: The fade is from the trial on this page and matches what users say. The rat testes finding is from an animal study on this page. The flushes, headaches, sex drive and blood work reports are user reports from r/Peptides and steroid forums, not from any trial.
My bottom line
In an IVF clinic, in one shot, this is the real thing. Sold to men as a daily testosterone booster, it fades in weeks, the one mood trial came back empty, and the rat study is a warning. I would not use it that way.
An opinion, not a finding. I am a coach, not a doctor.
Overview
Genuinely good randomised human evidence, all of it about triggering egg maturation in IVF: oocyte maturation in 95% of 60 women at high risk of ovarian hyperstimulation syndrome, with no moderate, severe or critical cases. Chronic dosing causes tachyphylaxis, a randomised trial found no effect on anxiety, and chronic subcutaneous dosing caused testicular degeneration in adult male rats.
Kisspeptin-54 is one of the better-evidenced compounds on this site, and the evidence points somewhere very specific that has almost nothing to do with how it is sold.
It is the 54 residue product of the KISS1 gene, acting at KISS1R upstream of GnRH neurons. Give it to a human and luteinising hormone rises. That is not a proposed mechanism, it is a directly measured one, repeatedly, in published randomised trials.
The clinical programme that matters was run at Imperial College London and Hammersmith Hospital, and it used kisspeptin-54 as a trigger for oocyte maturation in IVF, specifically in women at high risk of ovarian hyperstimulation syndrome. That is a real clinical problem with a real safety stake, and the results were good. In a phase 2 trial of 60 such women, oocyte maturation occurred in 95%, and across all doses and 51 embryo transfers the biochemical pregnancy, clinical pregnancy and live birth rates were 63%, 53% and 45%. No woman developed moderate, severe or critical ovarian hyperstimulation syndrome. A follow-on randomised trial of 62 women showed a second dose at ten hours improved oocyte yield.
Three findings sit against the way kisspeptin is marketed, and all three are published.
Chronic administration causes tachyphylaxis. The response fades. This was established in women with hypothalamic amenorrhoea and is the central problem for any repeated-dose consumer use.
A randomised controlled trial published in 2025 gave kisspeptin to humans and measured anxiety. Reproductive hormones rose. Anxiety did not change.
And chronic subcutaneous kisspeptin-54 caused testicular degeneration in adult male rats. That is an animal finding and it is labelled as one, but it is a direct test of the exact pattern of use, chronic subcutaneous dosing in a male, that the consumer market describes.
Mechanism of action
Demonstrated in humans, not proposed. Kisspeptin-54 binds KISS1R, formerly GPR54, on hypothalamic GnRH neurons, triggering release of an endogenous pool of GnRH, which drives pituitary luteinising hormone and follicle-stimulating hormone secretion. The downstream LH response has been measured directly in human trials by subcutaneous, intravenous and intranasal routes, and a single subcutaneous dose produces an LH surge the investigators describe as lasting roughly half a day. The receptor desensitises under continuous exposure, which is why chronic dosing produces tachyphylaxis rather than a sustained effect.
Human evidence
Substantial and randomised, concentrated almost entirely in reproductive endocrinology. Endpoints are oocyte yield, pregnancy rates, and luteinising hormone. The one behavioural endpoint ever tested, anxiety, was null.
- Phase 2, 60 women at high risk of OHSS: oocyte maturation in 95%, live birth 45% per transfer across 51 transfers, and zero moderate, severe or critical OHSS (PMID 26192876).
- Phase 2 randomised, 62 women, double blinded: a second dose at ten hours improved oocyte yield over saline (PMID 28854728). Registered NCT01667406, COMPLETED, 175 participants actual.
- Hypothalamic amenorrhoea: acute subcutaneous dosing stimulates gonadotropins, chronic dosing causes tachyphylaxis (PMID 19820030). Twice-weekly dosing for 8 weeks stimulated reproductive hormone release (PMID 20980998). Intravenous infusion increased LH pulsatility (PMID 24517142).
- Randomised controlled trial, 2025: reproductive hormones rose, anxiety did not change (PMID 40036336).
- Randomised controlled study, 2025: intranasal administration rapidly stimulated gonadotropin release (PMID 40215751).
- No trial of kisspeptin-54 has used a cognitive endpoint. No trial has measured libido, mood as a primary outcome, or body composition.
What this does not tell you: The trials answer a narrow question well and say nothing about the uses kisspeptin is marketed for. They were run in women, mostly women undergoing IVF or with hypothalamic amenorrhoea, at doses calibrated to trigger a single ovulatory LH surge. There is no dataset on men taking it repeatedly, no dataset on body composition, none on libido, and the one behavioural endpoint that was tested came back negative. Tachyphylaxis means a compound that works once may not work on the tenth occasion, and none of the IVF work involved repeated chronic dosing.
Reading the research record
There are two honest ways to describe kisspeptin-54 and they sound like opposite conclusions.
The first is that it works. In the setting it was developed for, triggering oocyte maturation in women at high risk of ovarian hyperstimulation syndrome, it produced maturation in 95% of women, live births, and not a single case of moderate or worse OHSS in a population selected for being at high risk of exactly that. That is a real result on a real endpoint and it is why the Imperial group kept going.
The second is that none of that transfers. Kisspeptin appears in consumer settings framed as a hormonal or libido compound for men. The published human record contains no such trial. What it does contain is a randomised trial of a behavioural endpoint that returned null, documented tachyphylaxis on chronic dosing, and a rat study in which chronic subcutaneous administration in adult males degenerated the testes.
A cognitive endpoint is a measured one: a validated test of working memory, processing speed, attention, executive function or episodic recall, administered before and after, against a control group who did not know which arm they were in. None of the compounds in this batch has ever been tested that way. Rating scales of fatigue, global clinical impression, anxiety or hyperphagia are not cognitive endpoints, and neither is a hormone level. This matters because the marketing for several of these compounds describes focus, clarity and mental energy, and the underlying studies measured none of those things.
On funding: this programme was investigator-led and academic, run at Imperial College London rather than by a company seeking a marketing authorisation. That explains why an approach with good phase 2 results has no phase 3 programme behind it, and it is a reason the evidence stops where it does rather than a verdict on the compound.
The evidence, charted
Fig. 1 · evidence composition
5of 6 citations (83%) are in people
Counted from the citation list on this page. The Human count is the same number shown in the badge at the top. Both understate any literature larger than the sources we cite.
Fig. 2 · evidence over time
Evidence spans 5 distinct years, 2006 to 2025, counted from the citation list on this page.
Fig. 3 · legal status at a glance
US
Not approved
UK
Not approved
AU
Not approved
CA
Not approved
Not approved in any of the four jurisdictions shown. A jurisdiction's classification is a regulatory fact, not a verdict on the science; see Legal status below for the full text and any notes.
Key studies & citations
- Human2015
Efficacy of Kisspeptin-54 to Trigger Oocyte Maturation in Women at High Risk of Ovarian Hyperstimulation Syndrome (OHSS) During In Vitro Fertilization (IVF) Therapy
Phase 2, multi-dose, open-label, randomised, 60 women at high risk of OHSS, Hammersmith Hospital, 2013 to 2014. Adaptive dose allocation across 3.2 nmol/kg (n=5), 6.4 (n=20), 9.6 (n=15) and 12.8 (n=20). Oocyte maturation occurred in 95% of women. Highest oocyte yield, 121%, followed the 12.8 nmol/kg dose. Across all doses and 51 transfers, biochemical pregnancy, clinical pregnancy and live birth rates were 63%, 53% and 45%. No woman developed moderate, severe or critical OHSS.
The Journal of Clinical Endocrinology and Metabolism - Human2017
A second dose of kisspeptin-54 improves oocyte maturation in women at high risk of ovarian hyperstimulation syndrome: a Phase 2 randomized controlled trial
Phase 2 randomised placebo-controlled, 62 women aged 18 to 34 at high risk of OHSS. All received kisspeptin-54 at 9.6 nmol/kg 36 hours before retrieval, then were randomised 1:1 to a second dose (n=31) or saline (n=31) ten hours later. Patients, embryologists and clinicians remained blinded. The second dose improved oocyte yield. Registered as NCT01667406, which the registry lists as COMPLETED with 175 participants actual across the programme.
Human Reproduction - Human2009
Subcutaneous injection of kisspeptin-54 acutely stimulates gonadotropin secretion in women with hypothalamic amenorrhea, but chronic administration causes tachyphylaxis
The single most important limitation for anyone considering repeated dosing, and it is in the title. Acute subcutaneous injection stimulates gonadotropin secretion in women with hypothalamic amenorrhoea; chronic administration causes tachyphylaxis, meaning the response diminishes with continued exposure.
The Journal of Clinical Endocrinology and Metabolism - Human2025
Kisspeptin Administration Stimulates Reproductive Hormones but Does Not Affect Anxiety in Humans
A clean randomised controlled negative on a behavioural endpoint. Kisspeptin administration raised reproductive hormones as expected and did not affect anxiety. This is the closest the kisspeptin literature comes to a psychological outcome measure, and the result was null.
The Journal of Clinical Endocrinology and Metabolism - Animal2006
Chronic subcutaneous administration of kisspeptin-54 causes testicular degeneration in adult male rats
Adult male rats, not humans. Chronic subcutaneous kisspeptin-54 caused testicular degeneration. The route, the dosing pattern and the sex all match the way kisspeptin is described in consumer settings, which is why this animal finding is reported here rather than left out.
American Journal of Physiology. Endocrinology and Metabolism - Human2025
Intranasal kisspeptin administration rapidly stimulates gonadotropin release in humans
A randomised controlled study extending the route: intranasal kisspeptin rapidly stimulated gonadotropin release in humans. Relevant because it establishes that a non-injected route works, and it still measures gonadotropins rather than any behavioural or cognitive outcome.
EBioMedicine
Frequently asked questions
What is the difference between kisspeptin-54 and kisspeptin-10?
They come from the same precursor. The KISS1 gene product is annotated with metastin at residues 68 to 121, which is the 54 residue peptide, and shorter fragments at 108 to 121, 109 to 121 and 112 to 121. Kisspeptin-10 is that last fragment, YNWNSFGLRF, and it is the one usually sold. The IVF trial programme used kisspeptin-54, not kisspeptin-10, so the oocyte and live birth numbers belong to the longer peptide.
Does kisspeptin raise testosterone or libido in men?
It raises luteinising hormone, which is upstream of testosterone, and that response is measured directly in human studies. Whether that produces a meaningful testosterone or libido outcome in men over time has not been tested in a published trial. The only behavioural endpoint anyone has run, anxiety, was null. Anyone telling you the libido question is settled is describing a mechanism, not a result.
Can I take it every day?
The published evidence argues against it. Chronic administration causes tachyphylaxis, meaning the gonadotropin response fades with continued exposure, and that finding is in the title of the study that established it. Separately, chronic subcutaneous administration in adult male rats caused testicular degeneration. Neither point is a prediction about humans dosing daily, because nobody has run that study, and both point the same direction.
Is it approved anywhere?
No. There is no approved kisspeptin product in any jurisdiction. The strong phase 2 results have not been followed by a registrational phase 3 programme, largely because the work was academic rather than commercial.
Does kisspeptin do anything for mood or focus?
No controlled trial has measured focus, attention, memory or any cognitive outcome with kisspeptin. The one psychological endpoint tested in a randomised trial was anxiety, and it did not change while reproductive hormones rose.