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Kisspeptin vs gonadorelin vs hCG: how they differ

Written by The Peptide Record editorialClinical review not yet completedLast reviewed 1 October 2026Funding No ads, no affiliate links, no vendor payment

Kisspeptin, gonadorelin and hCG all relate to the reproductive hormone system, but they work at different points and have three different regulatory records. FDA’s records show no kisspeptin product, two discontinued gonadorelin products, and approved hCG products with narrow labelled uses.

On this page

  1. Side by side
  2. The hormone chain in one paragraph
  3. What the evidence is, and is not
  4. What each status means for a product you see
  5. Scope of this page
  6. As of this review

In brief

Should you care? Yes, if you have seen the three names grouped together and want to know what actually separates them. The differences are where each acts in the hormone chain and what each has in FDA’s records.

The short version

  • Kisspeptin: a natural hormone studied in research trials. FDA’s drug-approval data list no kisspeptin product.15
  • Gonadorelin: the same molecule as the brain’s GnRH. FDA’s data list two human products, both discontinued.56
  • hCG: approved for narrow uses, with a label that says it has not been demonstrated to be effective for obesity.4

Side by side

Kisspeptin, gonadorelin and hCG compared
KisspeptinGonadorelinhCG (human chorionic gonadotropin)
What it isA natural peptide hormone; kisspeptin-54 is the main form circulating in humans1Synthetic GnRH, the hypothalamic hormone that triggers release of LH and FSH from the pituitary6A hormone made by the placenta, with alpha and beta subunits; its label describes the product as a water-soluble glycoprotein34
Where it actsStudied for its effect on reproductive hormone release; people with mutations that inactivate kisspeptin signaling are infertile, and animal studies suggest it helps generate the LH surge needed for ovulation1At the pituitary, prompting LH and FSH release6Acts like LH, acting on the gonads: the label describes it as virtually identical in action to pituitary LH, with a small FSH-like effect34
What FDA’s records showNo kisspeptin entry in FDA’s drug-approval data5Two human products on record, Factrel and Lutrepulse, both marked discontinued5Approved prescription products on record (Pregnyl is listed by name; Novarel has a current label), under biologics license applications345
Labelled usesNone: not an approved drugNone for humans currently marketedPrepubertal cryptorchidism not due to a physical blockage; selected cases of hypogonadotropic hypogonadism in males; inducing ovulation in certain infertile women34
Human trials cited hereTwo research-setting trials: IVF egg maturation (53 women) and brain imaging (29 men)12None cited hereThe label’s own clinical pharmacology; no trial cited here

The hormone chain in one paragraph

Reproduction is controlled by a relay. The hypothalamus releases GnRH, which makes the pituitary release LH and FSH, and LH and FSH act on the gonads (the ovaries and testes).63 Gonadorelin is GnRH itself. hCG acts like LH, so it works on the gonads directly. Kisspeptin is a separate hormonal signal in the same system; the research trials describe it as stimulating reproductive hormone secretion.1 Because they act through different routes, the three are not interchangeable.

What the evidence is, and is not

  • Kisspeptin, IVF study. In a 2014 study, 53 women having IVF each received a single kisspeptin-54 injection at one of four doses to trigger egg maturation. Eggs matured at every dose tested; 49 of 53 (92%) had fertilization and embryo transfer, and 21 of 53 (40%) had a biochemical pregnancy and 12 of 53 (23%) a clinical pregnancy.1 The abstract describes doses given to all 53 women, with no comparison group.
  • Kisspeptin, brain-imaging study. In a 2017 randomized study of 29 healthy men, kisspeptin compared with vehicle increased limbic-brain activity in response to sexual and couple-bonding images and was linked to mood and reward measures.2 It measured brain activity and questionnaires in a laboratory, not any treatment outcome.
  • Gonadorelin. FDA’s records show approved human products existed; they do not tell us why the products were discontinued, and we do not state a reason.5
  • hCG. Its label says hCG “has not been demonstrated to be effective adjunctive therapy in the treatment of obesity,” and that there is no substantial evidence it increases weight loss beyond that resulting from caloric restriction.34

The two kisspeptin studies were done under research protocols in monitored settings. Their results cannot be carried over to any product sold to the public.

What each status means for a product you see

  • Anything sold as kisspeptin is not an FDA-approved medicine: FDA’s data show none.5
  • Anything sold as human gonadorelin is not one of the FDA-approved products on record, which are discontinued.5
  • hCG has approved products with a label, listed by FDA under biologics license applications; see where FDA draws the line between a peptide and a biologic. A product sold for weight loss is outside its labelled uses.345
  • “Research use only” does not change any of this; see what it actually means.

Scope of this page

This page is a plain comparison of what each substance is and what the public records say. It gives no dosing and does not cover using any of them for fertility, hormone therapy or any other purpose outside a label. Those are decisions for a qualified prescriber. We do not name, rank or recommend any seller. See each substance on its own: kisspeptin, gonadorelin and hCG.

As of this review

As of 1 October 2026

This page follows the two kisspeptin publications, the current Novarel and Pregnyl labels on DailyMed, and FDA’s Drugs@FDA data as served by openFDA (last updated 29 September 2026). Absence of a record is described as what we found in those data, not as a legal finding. We will revise and date this page if FDA’s records change or a reader shows us an error (use the “Report an error” topic on About).

What you can do next

References

  1. Jayasena CN, Abbara A, Comninos AN, et al. “Kisspeptin-54 triggers egg maturation in women undergoing in vitro fertilization.” J Clin Invest 2014;124(8):3667-3677. DOI 10.1172/JCI75730, PMID 25036713. Abstract read in the PubMed record. PubMed
  2. Comninos AN, Wall MB, Demetriou L, et al. “Kisspeptin modulates sexual and emotional brain processing in humans.” J Clin Invest 2017;127(2):709-719. DOI 10.1172/JCI89519, PMID 28112678. Abstract read in the PubMed record. PubMed
  3. Pregnyl (chorionic gonadotropin) for injection, prescribing information, revised 03/2025. National Library of Medicine DailyMed. DailyMed
  4. Novarel (chorionic gonadotropin) for injection, prescribing information. National Library of Medicine DailyMed. DailyMed
  5. U.S. Food and Drug Administration, Drugs@FDA application data (Factrel, Lutrepulse, chorionic gonadotropin products; no kisspeptin match), via openFDA, data last updated 29 September 2026. open.fda.gov
  6. Factrel (gonadorelin) injection, FDA-approved veterinary label for cattle, which describes gonadorelin as the gonadotropin-releasing hormone produced by the hypothalamus. National Library of Medicine DailyMed. DailyMed