Does Kisspeptin Increase Testosterone? What the Human Studies in Men and Women Actually Show

Yes, kisspeptin increases testosterone in men, at least in the short term. In acute studies of healthy young men, testosterone went up within hours, while in healthy older men the rise was smaller or not significant, because kisspeptin makes the brain release GnRH, GnRH tells the pituitary to release luteinizing hormone (LH), and LH tells the testes to make testosterone. The harder questions are how big that rise is, whether it lasts beyond a few days, and what happens when kisspeptin is given continuously, and on those questions the evidence is thinner and, in one case, points the opposite way.

If you have seen kisspeptin sold online as a testosterone or libido peptide, whether you are reading for yourself or for a partner, this is the evidence behind those claims. What follows walks through the human studies in healthy men, in men with low testosterone, in older men and in women, and explains why the dosing pattern matters as much as the dose. For background on what kisspeptin is and where it sits in the hormone axis, our explainer Kisspeptin: The Master Switch Above the Hormone Axis covers the basics. This is educational content about published research rather than medical advice, and kisspeptin is not an approved medicine anywhere.

Kisspeptin increases testosterone indirectly, because it never acts on the testes themselves. Kisspeptin activates the KISS1 receptor on GnRH neurons in the hypothalamus, GnRH tells the pituitary to release LH and FSH, and LH stimulates the Leydig cells of the testes to produce testosterone. Any testosterone effect from kisspeptin therefore depends on a responsive hypothalamus, a responsive pituitary and testes that can still answer the LH signal.

That chain explains why researchers studying low testosterone are interested in kisspeptin. Testosterone therapy replaces the end product and switches your own axis down, whereas kisspeptin, in principle, pushes the body's own axis harder from the top. The same chain also explains why kisspeptin cannot help when the testes themselves are the problem, which is a point the data in older men make clearly.

Kisspeptin increased testosterone within hours in acute studies of healthy young men, and the size of the rise depended on the form of kisspeptin, the dose and how long it was given, while studies in healthy older men found a smaller or nonsignificant rise (Abbara 2018, Ullah 2019).

The first study of kisspeptin in men came from Dhillo and colleagues at Imperial College London (Journal of Clinical Endocrinology and Metabolism, 2005, pubmed.ncbi.nlm.nih.gov/16174713). In a double blind, placebo controlled crossover study, 6 healthy men each received a 90 minute intravenous infusion of Kisspeptin-54. Mean LH over 90 minutes was 10.8 U/L with kisspeptin versus 4.2 U/L with saline, and mean testosterone over 180 minutes was 24.9 nmol/L versus 21.7 nmol/L. The same study measured a plasma half life of 27.6 minutes for Kisspeptin-54.

Longer exposure produced a larger testosterone rise. George and colleagues reported (Journal of Clinical Endocrinology and Metabolism, 2011, pubmed.ncbi.nlm.nih.gov/21632807) that a Kisspeptin-10 infusion of 4 μg/kg per hour for 22.5 hours raised LH from 5.4 to 20.8 IU/L and testosterone from 16.6 to 24.0 nmol/L in 4 healthy men. A lower infusion rate of 1.5 μg/kg per hour increased LH pulse frequency from 0.7 to 1.0 pulses per hour, which means Kisspeptin-10 made the GnRH pulse generator fire more often.

The same paper found a ceiling with single injections, since an intravenous bolus of Kisspeptin-10 produced its maximal LH response at 1 μg/kg (LH rose from 4.1 to 12.4 IU/L at 30 minutes) while a 3 μg/kg bolus produced a smaller response than 1 μg/kg, so a bigger dose of Kisspeptin-10 was not a better one.

Kisspeptin raised testosterone in one small proof of concept study of men with type 2 diabetes and low testosterone, although only 4 men were in the infusion arm and the infusion lasted 11 hours.

George and colleagues published the study in Clinical Endocrinology in 2013 (pubmed.ncbi.nlm.nih.gov/23153270). The participants were 5 men with type 2 diabetes and low testosterone, with a mean BMI of 40.6 and a mean total testosterone of 8.5 nmol/L. In 4 of them, an 11 hour Kisspeptin-10 infusion at 4 mcg/kg per hour raised LH from 3.9 to 20.7 IU/L and testosterone from 8.5 to 11.4 nmol/L, and the authors concluded that the result suggested a potential therapeutic role for kisspeptin agonists in men with type 2 diabetes and central hypogonadism.

The finding matters because it shows the hypothalamus in these men can still respond, which supports the idea that some obesity and diabetes related low testosterone is driven from the brain. It does not show that kisspeptin treats low testosterone, because nobody has published a trial in men with low testosterone that gave kisspeptin for weeks and measured symptoms, body composition or testosterone over the long term. If you are tracking hormone markers, our guide to what blood work actually matters on a peptide protocol explains which tests are worth running.

Repeated kisspeptin dosing can keep the axis stimulated, but only when the exposure is intermittent, because continuous or frequent exposure blunts the response and a potent long acting analog suppresses testosterone entirely.

The most relevant study for anyone asking whether kisspeptin can raise testosterone over days was published in the European Journal of Endocrinology in 2026 (pubmed.ncbi.nlm.nih.gov/42549827). Yeung and colleagues at Imperial College London ran a randomized, single blinded, placebo controlled study in 15 healthy men using subcutaneous Kisspeptin-10 infusions. Acute subcutaneous infusions of 1.25 to 10.0 nmol/kg per hour raised LH, FSH and testosterone dose dependently compared with vehicle. A continuous infusion at 180 nmol per hour for 5 days left testosterone elevated, but LH and FSH fell back to levels similar to vehicle.

Daily 8 hour infusions at 150 nmol per hour, with 16 hours off each day, sustained higher LH over 12 days. The mean LH increase was +1.68 IU/L on day 1 and +1.14 IU/L on day 12, compared with -0.16 IU/L on vehicle, and the authors concluded that chronic subcutaneous kisspeptin sustains gonadotropin and testosterone secretion in healthy men for 12 days. Keep the scale in mind, because the LH effect on day 12 was smaller than on day 1, the study was small, and 12 days is still a short window.

Continuous kisspeptin desensitizes the system. A small 2026 study from Massachusetts General Hospital, published in Hormones (pubmed.ncbi.nlm.nih.gov/42230485), gave 3 healthy men a continuous intravenous Kisspeptin-10 infusion for 24 hours. LH rose 5 to 8 times above baseline and peaked within 12 to 20 hours, then declined by 13% to 47% from that peak before the infusion ended, while FSH and testosterone rose modestly.

The same pattern appeared earlier in women. Jayasena and colleagues reported (Journal of Clinical Endocrinology and Metabolism, 2009, pubmed.ncbi.nlm.nih.gov/19820030) that twice daily subcutaneous Kisspeptin-54 at 6.4 nmol/kg in women with hypothalamic amenorrhea produced a mean maximal LH increment of 24.0 IU/L on the first day but only 2.5 IU/L on day 14. The authors called this tachyphylaxis, which means the body stops responding to repeated doses.

Sustained exposure to a potent kisspeptin analog lowered testosterone to castration levels. MacLean and colleagues reported two phase 1 studies of TAK-448, an investigational kisspeptin analog, in the Journal of Clinical Endocrinology and Metabolism in 2014 (pubmed.ncbi.nlm.nih.gov/24762108). After a single bolus or 2 hour injection, testosterone rose by roughly 1.3 to 2 times by 48 hours. During a 14 day infusion at doses above 0.1 mg per day, however, testosterone dropped below baseline by 60 hours and reached a sustained castration level by day 8, which is exactly why TAK-448 was developed for prostate cancer.

This is the single most important point if you are reading online claims that kisspeptin boosts testosterone. The same receptor that raises testosterone when it is stimulated briefly can shut testosterone production down when it is stimulated constantly, which is also how GnRH agonists such as leuprolide work, so the dosing pattern decides the direction of the effect. Our guide to peptide half life and dosing frequency explains why exposure timing changes what a peptide does.

Kisspeptin still triggers LH release in older men, but the testosterone rise is smaller, which suggests the testes rather than the brain limit the response.

Abbara and colleagues compared 5 healthy older men with a mean age of 59.3 against young men with a mean age of 28.9 (Neuroendocrinology, 2018, pubmed.ncbi.nlm.nih.gov/29544222). Each man received 3 hour infusions of Kisspeptin-54 at 0.1, 0.3 or 1.0 nmol/kg per hour. The gonadotropin response in older men was at least as strong as in young men, but the testosterone rises after every dose were reduced in the older group. The paper notes that male testosterone falls by about 1% per year from age 40.

A 2019 study in Andrologia by Ullah and colleagues (pubmed.ncbi.nlm.nih.gov/30590872) found the same pattern with a single 1 µg/kg Kisspeptin-10 bolus, since LH rose in adult, middle aged and older men while testosterone rose significantly only in the youngest group. The authors concluded that Leydig cell responsiveness to the LH signal declines with age. In practical terms, kisspeptin cannot do more than your testes allow, so in men whose testosterone is low because the testes respond poorly, pushing the brain harder achieves little.

Published evidence on kisspeptin and testosterone in women is limited, because the human kisspeptin trials in women have focused on LH, FSH, estradiol, ovulation and egg maturation rather than testosterone.

In 12 women with polycystic ovary syndrome (PCOS), twice daily subcutaneous Kisspeptin-54 at 6.4 to 12.8 nmol/kg for 21 days caused a small rise in LH with an equivalent rise in estradiol, and 2 of the women ovulated (Romero-Ruiz and colleagues, Human Reproduction, 2019, pubmed.ncbi.nlm.nih.gov/31820802). In healthy premenopausal women undergoing mild ovarian stimulation, a single 3 μg dose of the kisspeptin receptor agonist MVT-602 produced a mean maximum LH rise of 82.4 IU/L at 24.8 hours (Abbara and colleagues, Fertility and Sterility, 2024, pubmed.ncbi.nlm.nih.gov/37925096).

In women, ovarian androgen production is partly driven by LH, so a testosterone effect is biologically plausible, but plausibility is not evidence and none of these studies reported a testosterone outcome in its abstract. PCOS adds a further caution, because the condition already involves high LH activity and high androgens, so pushing LH higher is not an obvious goal for you outside a supervised fertility protocol.

Kisspeptin changed sexual brain processing in randomized trials in both women and men with low sexual desire, and in men it also increased a physical arousal measure, but these were single session studies rather than treatment trials.

Thurston and colleagues (JAMA Network Open, 2022, pubmed.ncbi.nlm.nih.gov/36287566) randomized 40 premenopausal women with hypoactive sexual desire disorder (HSDD), and 32 completed both visits. A 75 minute Kisspeptin-54 infusion changed brain activity in sexual and facial attraction processing regions on fMRI, and kisspeptin was well tolerated with no reported adverse effects, although the main outcome was brain imaging rather than a change in everyday desire.

Mills and colleagues (JAMA Network Open, 2023, pubmed.ncbi.nlm.nih.gov/36735255) randomized 37 men with HSDD, of whom 32 completed. During a 75 minute infusion, kisspeptin modulated sexual brain processing and increased penile tumescence in response to sexual stimuli by up to 56% more than placebo. Because these effects appeared within a single infusion, they are more likely driven by brain signaling than by a slow testosterone rise, and whether repeated kisspeptin dosing improves libido over weeks has not been tested.

There is no published human evidence that ipamorelin or CJC-1295 increases testosterone, because both peptides target the growth hormone axis rather than the reproductive axis.

CJC-1295 is a long acting GHRH analog. In the randomized trials reported by Teichman and colleagues (Journal of Clinical Endocrinology and Metabolism, 2006, pubmed.ncbi.nlm.nih.gov/16352683), a single injection raised mean GH 2 to 10 times for 6 days or more and IGF-1 1.5 to 3 times, with an estimated half life of 5.8 to 8.1 days. The outcomes were GH and IGF-1, and testosterone was not a reported outcome. Ipamorelin is a ghrelin receptor agonist that releases GH, and its human research base is small, so claims that either peptide boosts testosterone are not supported by trial data. Our CJC-1295 and ipamorelin guides cover what those peptides have actually been studied for.

Most of what matters for real world use is unknown. The longest controlled human study of kisspeptin and testosterone in men lasted 12 days, and no trial has tested kisspeptin in men with low testosterone for weeks or months, measured symptoms such as energy, libido or muscle, or compared kisspeptin with testosterone therapy, clomiphene or hCG. The best intermittent dosing pattern in humans is not established either, and the subcutaneous protocol that worked in the 2026 study used 8 hour infusions rather than simple injections.

Kisspeptin is not approved by the FDA or any other regulator for any use, and material sold online as Kisspeptin-10 for research carries no assurance of identity, purity or dose. If you are considering any hormone affecting peptide, a clinician who can order and interpret your labs is essential.

Does kisspeptin increase testosterone? In men it does, acutely, since studies in healthy young men found a rise within hours, and one small study found the same in men with type 2 diabetes and low testosterone. The effect depends on intermittent exposure, because continuous exposure blunts the LH response and a potent continuous analog drives testosterone down to castration levels. Older men show a smaller testosterone response because their testes respond less, and in women the evidence on testosterone is limited.

Kisspeptin is a promising research tool for understanding and possibly treating brain driven low testosterone, but it is not yet a proven or approved testosterone therapy, and the gap between a rise measured over hours in a hospital and a treatment you could use for months is still wide.