Kisspeptin-10

What kisspeptin is

Kisspeptin is also known by its older name metastin. Its central importance became apparent in 2003: people with a defective kisspeptin receptor, then called GPR54, do not enter puberty. Their pituitary gland works, but the start signal from above is missing. Since then, kisspeptin has been regarded as the switch that turns on the reproductive axis.

The body produces kisspeptin in several lengths. The best-known forms are kisspeptin-54 and the short kisspeptin-10, both naturally occurring. Clinical research mainly uses kisspeptin-54, the scene almost exclusively kisspeptin-10. In a direct comparison in healthy men, both forms triggered a similarly strong hormonal response.

How it works

Kisspeptin nerve cells in the hypothalamus set the rhythm at which GnRH is released. GnRH in turn causes the pituitary gland to release LH and FSH, which drive the testes or ovaries. Kisspeptin therefore acts one level above gonadorelin and two levels above hCG. Because it uses the body’s own regulation instead of bypassing it, it is considered a particularly physiological approach.

The hormonal response is measurable but moderate. In healthy men, LH under GnRH infusion was about 3-fold higher than under kisspeptin-10. And as with GnRH, the rhythm matters: in a 2026 study in healthy men, daily administration with breaks kept LH and FSH elevated over 12 days. With 5 days of continuous infusion, by contrast, LH and FSH fell back to the level under placebo; only testosterone remained elevated. Under continuous administration, stable kisspeptin derivatives even lowered testosterone in rats to castration levels within 3 to 7 days.

Besides the hormonal axis, kisspeptin acts in the brain on areas for reward, emotion and sexual attraction. This second effect is the reason why kisspeptin is now being studied as a possible agent against reduced sexual desire.

What it is used for

In medicine, kisspeptin is being researched, not used. The topics are absent puberty and hormone deficiency, reduced sexual desire and in vitro fertilization, in which kisspeptin is being tested as a gentler trigger of egg maturation because it mimics the natural LH peak.

In the scene, kisspeptin-10 is used for libido and as a building block of hormonal restart protocols, for example after a testosterone or anabolic steroid cycle. The logic of such protocols: kisspeptin for the hypothalamus, gonadorelin for the pituitary, hCG for the testes. This is mechanistically understandable, but as a combination it has never been studied.

What the studies show

Men with low desire, JAMA Network Open 2023

Mills and colleagues gave men with reduced sexual desire, double-blind on two occasions, kisspeptin-54 or placebo as an infusion over 75 minutes. Of 37 participants, 32 completed the study. While watching sexual videos, kisspeptin markedly changed activity in the brain’s sexual network, the primary endpoint. Erection increased by up to 56 percent more than under placebo, and the men reported looking forward to sex more.

Women with low desire, 2022

Using the same method, the group led by Thurston studied premenopausal women with reduced sexual desire, 40 randomized, 32 with both sessions. Kisspeptin changed the brain’s processing of erotic videos and attractive faces. The effects were associated with distress and with lower sexual aversion. No side effects were reported.

Kisspeptin-10 over 12 days, 2026

Yeung and colleagues gave 15 healthy men kisspeptin-10 under the skin, compared with 12 controls. Daily administration with long breaks kept LH and FSH elevated over 12 days, and the receptor continued to respond afterwards. A continuous infusion over 5 days, by contrast, brought LH and FSH back to placebo level. This is so far the longest controlled use of kisspeptin-10 and the most important study on the question of how repeated doses behave.

Where the data stop

The libido studies are snapshots: a single infusion in the laboratory, with kisspeptin-54, in people with diagnosed reduced desire. What was measured was mainly brain activity and responses to videos. Whether repeated injections of kisspeptin-10 increase libido in everyday life has not been tested in any study.

For use around testosterone therapy there are no data at all. A 2026 review notes that there are no studies specifically on testosterone therapy and that kisspeptin is considered experimental in this use. The longest controlled use lasted 12 days, and it shows that the rhythm of administration decides whether the axis is stimulated or desensitized. Most of the newer human studies also come from a research network around Imperial College in the UK, and the numbers of participants are small.

Status, approval and legal

Kisspeptin is not approved as a medicine in Germany or the EU and is in clinical research. What is offered online as kisspeptin-10 is declared as a research peptide. Usage and dosage information is therefore omitted. The 2026 Prohibited List of the World Anti-Doping Agency lists kisspeptin and its derivatives under S2.2.1 as testosterone-stimulating peptides in males. The ban applies at all times, in and out of competition. In the US, the FDA has listed kisspeptin-10 since September 2023 in Category 2 of bulk drug substances for compounding, that is, among substances with potential significant safety risks. In October 2024, an FDA expert panel voted against adding kisspeptin-10 to the list of substances permitted for compounding.

Safety

In the short studies, kisspeptin was well tolerated. Side effects were rarely or never reported with infusion and nasal spray, and in the study with 95 participants, anxiety, stress hormone, blood pressure and pulse remained unchanged. Long-term data are missing. The most important known risk is the paradoxical effect of continuous stimulation: the axis can become desensitized instead of stimulated, in the case of stable derivatives in animals down to a drop in testosterone to castration levels. Anyone combining hormonal protocols changes several levels of a finely regulated axis at the same time; that belongs under medical supervision with laboratory monitoring. There are no data for pregnancy and breastfeeding. Gray-market products are unverified in purity and content.

Sources

• Seminara SB et al., New England Journal of Medicine 2003 — kisspeptin receptor and puberty
• Mills EG et al., JAMA Network Open 2023 — kisspeptin in men with reduced sexual desire
• Thurston L et al., JAMA Network Open 2022 — kisspeptin in women with reduced sexual desire
• Yeung AC et al., European Journal of Endocrinology 2026 — kisspeptin-10 over 12 days in healthy men
• Mills EG et al., Journal of Clinical Endocrinology and Metabolism 2025 — no effect on anxiety, 95 participants
• Jayasena CN et al., Human Reproduction 2015 — kisspeptin-10, kisspeptin-54 and GnRH compared
• George JT et al., Clinical Endocrinology 2013 — kisspeptin-10 in men with type 2 diabetes
• Matsui H et al., European Journal of Pharmacology 2014 — continuous administration of kisspeptin analogues in rats
• Cretu AM et al., Frontiers in Reproductive Health 2026 — peptide strategies during testosterone therapy
• WADA Prohibited List 2026, officially published in the Austrian Federal Law Gazette III No. 219/2025
• FDA — bulk drug substances with potential significant safety risks (Category 2), kisspeptin-10
• FDA — meeting of the Pharmacy Compounding Advisory Committee on October 29, 2024 (including kisspeptin-10)