Kisspeptin

The master switch at the top of the reproductive axis. Given in pulses it stimulates, given continuously it suppresses.

Evidence: BHuman trials what's this?
Grade B for hormone and sexual-response effects. Physique uses are Grade D.
Also known as: KISS1 peptide · Kisspeptin-10 (KP-10) · Kisspeptin-54 (KP-54) · metastin
Class: Natural reproductive neuropeptide; KISS1R agonist. Investigational.

The 30-second version

WhatA hypothalamic peptide that drives GnRH, then LH and FSH, then testosterone or oestrogen.

Why people use itRaising testosterone without shutting down natural production, plus libido and fertility.

The honest catchRun it continuously at high doses and it can push testosterone down to castration levels.

What it is

Kisspeptin was found in 1996 as a cancer-metastasis suppressor and named after Hershey’s Kisses, from the town where it was discovered. In 2003, scientists found that people unable to make working kisspeptin never went through puberty, which placed it at the top of the reproductive axis. KP-54 is the long form used in many trials. KP-10 is the short active fragment. Both hit the same receptor.

How it works

KISS1R on hypothalamic GnRH neurons is activated.

GnRH pulses travel to the pituitary.

LH and FSH are released.

Gonads. Testosterone in men, oestrogen and progesterone in women; FSH supports sperm and eggs.

Pattern is everything. Pulsatile dosing stimulates. Continuous high dosing desensitises the receptor and suppresses.

Unlike testosterone itself, which shuts your own production down, kisspeptin works through your own system from the top.

What the research shows

Healthy men: a KP-10 injection gave a rapid, dose-dependent LH rise of about 2.5-fold, with the maximum effect around 1 mcg/kg and a smaller response above that, showing desensitisation¹. Women with hypothalamic amenorrhoea: KP-54 powerfully stimulated a shut-down axis². Nasal form: rapidly raised gonadotropins with no side effects reported³. Brain: it enhanced sexual and emotional processing without raising anxiety⁴. It is also an effective, safe trigger for egg maturation in IVF.

Same molecule, opposite effect, depending on how often you take it.

Evidence at a glance

Use	Grade	Best evidence	Main gap	Read
Raises LH and testosterone	BHuman trials	~2.5-fold LH rise¹	Short-term	Real
Libido, sexual processing	BHuman trials	Enhanced processing, no anxiety⁴	Not a physique outcome	Supported
Reproductive disorders, IVF	BHuman trials	Effective in amenorrhoea; IVF trigger^2,3	Investigational	Strong signal
Continuous high dose	BHuman trials	Desensitises and suppresses²	Opposite effect	Dose pattern critical

Dosing: what has been reported

Not a recommendation. These figures describe what was studied or what circulates in practice, kept separate so you can see how solid each one is. Speak with a qualified clinician before acting on any of it.

Setting	Figure	Route	Grade
Published human	KP-10 IV 0.01–3 mcg/kg (peak ~1 mcg/kg); KP-54 SC twice weekly ×8 weeks; nasal ~12.8 nmol/kg^1,2,3	IV / SC / nasal	B
Community	~100 mcg, daily or several times weekly, kept intermittent	Subcutaneous	D

KP-10 acts fast and briefly. KP-54 lasts longer. If the effect fades with heavy use, that’s desensitisation. Pushing harder makes it worse.

Preparing & storing

Reconstitute with bacteriostatic water and refrigerate. KP-10 is the more fragile form.

Reported side effects

Very few effects: several trials reported none
Occasional mild flushing or headache; injection-site redness
Increased libido (often the intended effect)
Paradoxical suppression with continuous high dosing

Worth tracking: total and free testosterone, LH, FSH, oestradiol, and PSA in men over 40.

Who should avoid it

Hormone-sensitive cancers (prostate, breast)
Pregnancy
On TRT: it contradicts the purpose. GnRH drugs oppose it.
Fertility treatment: coordinate with your doctor
Tested athletes: likely prohibited in males (LH-releasing factor)

Regulatory status checked Oct 2026

Body	Status	Detail
FDA (US)	Not approved	In clinical development.
EMA (EU)	Not approved	—
CDSCO (India)	Not approved	—
WADA	Likely prohibited (males)	LH and releasing-factor category.

The NexGen read

Human-proven, if you respect the rhythm

Kisspeptin has some of the best human data of any research peptide, and a notably clean safety record. Dose it in pulses, monitor your hormones, and don’t expect physique results the trials never measured.

References

George JT, Anderson RA, Millar RP, et al. Kisspeptin-10 is a potent stimulator of LH and increases pulse frequency in men. J Clin Endocrinol Metab. 2011;96(8):E1228–E1236.
Skorupskaite K, George JT, Anderson RA. The kisspeptin–GnRH pathway in human reproductive health and disease. Hum Reprod Update. 2014;20(4):485–500.
Intranasal kisspeptin administration rapidly stimulates gonadotropin release in humans. PMC12018048
Kisspeptin administration stimulates reproductive hormones but does not affect anxiety in humans. J Clin Endocrinol Metab. 2025;110(11):3133.