hCG and kisspeptin turn up in the same conversations — fertility treatment, testosterone, the "restart" protocols that circulate around anabolic steroid use — and they are often described as alternatives. They are not alternatives in any mechanical sense. One replaces a hormone at the end of the chain; the other pulls a lever at the top of it and depends on everything in between still working.
The labelled hCG figures and their units are on our hCG dosage page, and the published kisspeptin protocols on our kisspeptin dosage page. hCG's comparison with the other upstream option, gonadorelin, is on our gonadorelin vs hCG page. This page puts hCG and kisspeptin side by side.
Side by side
| hCG | Kisspeptin | |
|---|---|---|
| Where it acts | LH receptor, testis and ovary | GnRH neurons in the hypothalamus |
| Needs a working pituitary | No | Yes |
| Half-life | ~29 hours, subcutaneous (Ovidrel label) | 27.6 minutes, kisspeptin-54, IV (2005) |
| FDA-approved products | Novarel, Pregnyl, Ovidrel | None |
| Approved uses | Ovulation induction; hypogonadotropic hypogonadism in men; prepubertal cryptorchidism | — |
| Largest controlled record | Decades of label-backed use in IVF | Phase 2 IVF trials, Imperial College London |
| Principal labelled serious risk | Ovarian hyperstimulation syndrome (with menotropins) | Not established |
| Head-to-head trial | None found | None found |
Two ends of one chain
The reproductive axis runs from brain to gonad: kisspeptin neurons signal GnRH neurons, GnRH tells the pituitary to release LH and FSH, and LH acts on the testis or ovary.
hCG enters at the bottom. The Novarel label describes its action as "virtually identical to that of pituitary LH": it stimulates the testis's Leydig cells to make testosterone and supports the corpus luteum of the ovary. It does not need a brain or pituitary signal to work, which is why it is approved for hypogonadotropic hypogonadism — a condition in which that signal is missing.
Kisspeptin enters at the top. In a 2005 placebo-controlled crossover study in six men (PMID 16174713), a 90-minute intravenous infusion of kisspeptin-54 raised mean LH from 4.2 to 10.8 U/L, FSH from 3.2 to 3.9 U/L and testosterone from 21.7 to 24.9 nmol/L against saline. Every one of those rises was the body's own hormone, released by the body's own pituitary. If the pituitary cannot respond, kisspeptin has nothing to pull.
A sixty-fold difference in how long each lasts
Recombinant hCG's label gives a mean terminal half-life of 29 ± 6 hours after a subcutaneous dose, and about 26.5 hours after an intravenous one. The same 2005 study measured kisspeptin-54's plasma half-life at 27.6 ± 1.1 minutes. Kisspeptin-10, the shorter fragment most often sold as research material, is a different molecule again — the two forms, and why their figures cannot be swapped, are explained on the kisspeptin dosage page.
The difference matters most in IVF. An hCG trigger keeps stimulating the ovary for days. A kisspeptin trigger produces an LH surge from the woman's own pituitary, which then winds down on its own. That is the whole rationale for testing kisspeptin as a trigger.
The IVF record
hCG. The Novarel label lists the principal serious adverse reactions when hCG is used with menotropins: ovarian hyperstimulation syndrome — "sudden ovarian enlargement, ascites with or without pain, and/or pleural effusion" — then enlargement or rupture of ovarian cysts, multiple births and arterial thromboembolism. Anaphylaxis has also been reported.
Kisspeptin-54. The Imperial College London group ran two trials:
- 2014 (PMID 25036713; NCT01667406). 53 women received a single subcutaneous injection of kisspeptin-54 at 1.6 to 12.8 nmol/kg. Egg maturation occurred at every dose; 92% went on to embryo transfer; clinical pregnancy was 23% (12 of 53).
- 2015 (PMID 26192876). 60 women at high risk of OHSS, randomised between four kisspeptin-54 doses. Oocyte maturation occurred in 95%; live birth was 45% per transfer across all doses; no woman developed moderate, severe or critical OHSS.
Neither trial had an hCG arm. The second compared doses of kisspeptin, in women chosen because they were at high risk, against no concurrent control. The absence of OHSS is striking for that group and is the reason the approach is being pursued — but it is not a measured comparison with hCG. A kisspeptin-receptor agonist, MVT-602, has since been tested in phase 1 and 2a trials (PMID 37925096); it is a separate drug candidate with its own figures.
The record in men
hCG is approved for hypogonadotropic hypogonadism in men and has a long clinical history on that label. Kisspeptin's male record is a set of small physiological studies. The most recent, published in August 2026 in the European Journal of Endocrinology (PMID 42549827), found that continuous kisspeptin-10 infusion for five days left gonadotropins "similar to vehicle" while testosterone stayed up, and that eight hours on, sixteen off for twelve days sustained the LH rise. The full design and figures are on the kisspeptin dosage page. No trial has compared kisspeptin with hCG in men, with or without prior testosterone use.
What the labels and the lack of one mean in practice
hCG comes as an approved product with a label that states its indications, its risks and — in capitals — that it "has not been demonstrated to be effective adjunctive therapy in the treatment of obesity." Its side-effect record is on our hCG side-effects page, and how its labelled products are mixed is on our hCG reconstitution page.
Kisspeptin has no label anywhere. Every human figure comes from a research protocol using material made for that study. A research-market vial labelled "kisspeptin" may be kisspeptin-10 or kisspeptin-54, at an unverified amount and purity; what a certificate of analysis can confirm is on our how to read a COA page.
What is not established
- Whether kisspeptin is safer than hCG as an IVF trigger in a randomised comparison; none has been run.
- Whether kisspeptin can do any job hCG is approved for in men.
- Any long-term safety record for kisspeptin; the longest human exposure found here is twelve days.
- Effects of either compound used outside medical supervision, which none of the trials studied.
What each molecule is lives in Peptide Lexicon's entries for hCG and kisspeptin, and MuscleLedger's kisspeptin page covers its sport and testing status. Decisions about fertility treatment or testosterone belong with a clinician.
Sources and dates
- NOVAREL (chorionic gonadotropin for injection), Ferring Pharmaceuticals — label effective 2025-08-27: indications, warnings, clinical pharmacology. Read via openFDA 2026-10-05.
- OVIDREL (choriogonadotropin alfa), EMD Serono — label effective 2023-12-26: pharmacokinetics. Read via openFDA 2026-10-05.
- Dhillo WS, et al. Kisspeptin-54 stimulates the hypothalamic-pituitary gonadal axis in human males. J Clin Endocrinol Metab. 2005;90(12):6609–15. PMID 16174713.
- Jayasena CN, et al. Kisspeptin-54 triggers egg maturation in women undergoing in vitro fertilization. J Clin Invest. 2014;124(8):3667–77. PMID 25036713; NCT01667406.
- Abbara A, et al. Efficacy of kisspeptin-54 to trigger oocyte maturation in women at high risk of ovarian hyperstimulation syndrome (OHSS) during in vitro fertilization (IVF) therapy. J Clin Endocrinol Metab. 2015;100(9):3322–31. PMID 26192876.
- Abbara A, et al. Endocrine profile of the kisspeptin receptor agonist MVT-602 in healthy premenopausal women with and without ovarian stimulation. Fertil Steril. 2024;121(1):95–106. PMID 37925096.
- Yeung AC, et al. Chronic subcutaneous kisspeptin-10 stimulates gonadotropin secretion for 12 days in healthy men. Eur J Endocrinol. 2026;195(2):206–216. PMID 42549827.
- ClinicalTrials.gov v2 API, intervention "kisspeptin" — 36 studies, titles screened for hCG, trigger, IVF and oocyte, 2026-10-05.
Corrections go to the contact page.