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D2C Peptides

Research goal

Peptides and testosterone

Evidence that any compound here raises testosterone comes only from short studies or narrow groups: kisspeptin-10 during IV infusions of up to 22.5 hours in a few men,12 pulsed gonadorelin in men with congenital hypogonadotropic hypogonadism,24 and hCG, which is FDA-approved for selected men with hypogonadotropic hypogonadism.16 Where growth hormone peptides were studied, LH, the hormone that drives the testes, did not change.353637 This page maps the compounds people search with testosterone and what published sources report on each; it makes no promise.

This page summarizes published sources for information only. It is not medical advice and does not tell anyone to use a product. Questions about your own health belong with a licensed clinician. For questions about an order or a product, contact us.

How the testosterone signal works

In men, the testes make testosterone on signals that start in the brain: kisspeptin releases GnRH, which raises the pituitary hormones LH and FSH,17 and hCG, which acts like LH, stimulates the Leydig cells of the testes to make androgens.1819 So a compound can act at the top of this chain, at the testes, or outside it. People searching for "testosterone peptides" meet all three kinds. The sections below follow that order and end with growth hormone peptides that people also look up for testosterone.

Compounds that act on the testosterone signal

Kisspeptin-10

Kisspeptin-10 is the 10-amino-acid end piece of the hormone kisspeptin.20 In 4 healthy men, a 22.5-hour intravenous infusion raised testosterone from 16.6 to 24.0 nmol/L,1 and an 11-hour infusion raised it from 8.5 to 11.4 nmol/L in 5 men with type 2 diabetes and low testosterone.2 FDA lists kisspeptin-10 in Category 2 of bulk substances for compounding, the group it says may present significant safety risks.21 Read What is Kisspeptin-10? or see Kisspeptin-10 for sale.

Gonadorelin

Gonadorelin is a lab-made copy of GnRH, the 10-amino-acid hormone from the hypothalamus that signals the pituitary to release LH and FSH.22 Its testosterone evidence comes from men whose own GnRH signal is missing: in a nonrandomized study of men with congenital hypogonadotropic hypogonadism, testosterone rose into the normal range in the 10 given gonadorelin in pulses by pump.2324 Continuous rather than pulsed exposure desensitizes the pituitary,22 as a 1978 study in monkeys showed, so pump results cannot be assumed for other schedules.25 The two FDA-approved human products, Factrel and Lutrepulse, are listed as discontinued.26 Read What is Gonadorelin? or see Gonadorelin for sale.

HCG

hCG is an FDA-approved prescription drug whose approved uses include selected cases of hypogonadotropic hypogonadism in men, and the prescriber sets the dose.16 Since March 23, 2020, FDA has regulated it as a biological product, so compounded versions no longer qualify for the exemptions in sections 503A and 503B.27 The 2026 WADA Prohibited List bans chorionic gonadotrophin in male athletes at all times.28 Read What is HCG? or see HCG for sale.

HMG

HMG supplies both FSH and LH activity.29 A 2008 review says injected hCG or LH stimulates testosterone production in men, and that athletes probably use them mainly to stimulate the testes during and after anabolic steroid use.30 No source reviewed tested HMG alone as a testosterone treatment; in the gonadorelin study above, 18 men received hCG plus HMG to start sperm production, and their testosterone also rose into the normal range.2324 Its US label covers only women having assisted reproduction, and the prescriber sets the dose.31 Read What is HMG? or see HMG for sale.

Testagen

The only testosterone data for Testagen come from a developer report that was not peer reviewed: in 48 men aged 54 to 68, average testosterone went from 6.1 to 7.3 ng/mL after 20 days of oral capsules added to standard care, against 6.5 ng/mL with standard care alone.32 A PubMed search finds no peer-reviewed study of Testagen and testosterone,33 and the report used only oral capsules, so there are no data for the injectable form.32 It is not FDA approved, and DailyMed lists no drug label for it.34 Read What is Testagen? or see Testagen for sale.

Growth hormone peptides: no testosterone effect shown

These peptides are studied for raising growth hormone.353740 Where studies measured LH, the pituitary hormone that drives the testes, it did not change (details under each compound).35363711 A 2020 review of growth hormone secretagogues, ipamorelin among them, in men with low testosterone found that data on their clinical efficacy largely remain lacking.38

Sermorelin

Sermorelin copies the active first 29 amino acids of growth hormone-releasing hormone and prompts the pituitary to release growth hormone.3940 No sermorelin-only study reviewed here reports an effect on testosterone; the closest data are the chart review of men on testosterone therapy covered in the questions below.1112 Read What is Sermorelin? or see Sermorelin for sale.

CJC-1295 + Ipamorelin

No study reviewed here tested this blend in men with low testosterone, and a ClinicalTrials.gov search returns no studies of the combination.42 In its 2024 review, FDA found three published human studies of CJC-1295, all of which gave the DAC version, not the form without DAC used in this blend, to healthy subjects.41 Read What is CJC-1295 + Ipamorelin? or see CJC-1295 + Ipamorelin for sale.

Ipamorelin

In swine, ipamorelin did not change LH or FSH, the pituitary hormones that drive testosterone production.35 It is not an FDA-approved drug.43 Read What is Ipamorelin? or see Ipamorelin for sale.

GHRP-2

GHRP-2 has not been shown to raise testosterone: in 33 men with prolonged critical illness, testosterone rose significantly only when GnRH pulses were added to GHRP-2 plus TRH, not with GHRP-2 alone.44 Read What is GHRP-2? or see GHRP-2 for sale.

GHRP-6

No GHRP-6 study reviewed measured testosterone: it did not change LH or FSH in 17 healthy men,36 and it did not release them in the original 1984 tests in pituitary tissue and animals.45 FDA lists GHRP-6 in Category 2 of bulk substances for compounding, which it says may present significant safety risks.46 Read What is GHRP-6? or see GHRP-6 for sale.

Tesamorelin

Tesamorelin (Egrifta WR) is FDA-approved only to reduce excess abdominal fat in adults with HIV and lipodystrophy, and the prescriber sets the dose.47 No source reviewed tested it as a testosterone treatment, and the label reports no clinically significant change in LH in its clinical trials.37 Read What is Tesamorelin? or see Tesamorelin for sale.

IGF-1

No study reviewed for this page measured testosterone after IGF-1 LR3, in people or in animals.78 The question below covers what its research did measure. Read What is IGF-1? or see IGF-1 for sale.

HGH

In an 8-week trial that gave growth hormone with or without testosterone to recreational athletes, sprint capacity rose 8.3% in men given both, against 3.9% with growth hormone alone in men and women combined.48 In a 26-week trial in older men, lean mass rose 4.3 kg with both, against 3.1 kg with growth hormone alone, but 32% of men on the combination had carpal tunnel symptoms.49 Somatropin is a prescription drug, and the prescriber sets the dose.50 Read What is HGH? or see HGH for sale.

How to read this research

Four points help when you weigh these findings. A rise during a lab infusion is not a lasting change: the kisspeptin-10 results come from intravenous infusions of 11 to 22.5 hours.12 The schedule can reverse the effect: in monkeys, pulsed GnRH kept the pituitary working while a constant infusion did not,25 and continuous dosing of a long-acting kisspeptin analog drove testosterone below the castration level in healthy men.6 Who was studied matters: the gonadorelin pump results come from men with congenital hypogonadotropic hypogonadism, not from men with normal hormone levels.24 And a blood level is not an outcome: most studies here measured hormones rather than symptoms, and the Testagen data are a single developer report that has not been replicated.3233 For the regulatory status and complete sources of any compound here, open its profile.

Other research goals

Frequently asked questions

Does kisspeptin raise testosterone levels?

Briefly, in small studies. Intravenous kisspeptin-10 infusions of 11 to 22.5 hours raised testosterone in 4 healthy men and in 5 men with type 2 diabetes and low testosterone, and single IV doses gave small rises; none of these studies lasted much longer than a day.123 A 75-minute infusion of the longer kisspeptin-54 did not change it in 32 men with low sexual desire.4 In phase 1 studies of healthy men, long-acting kisspeptin analogs given continuously did the opposite, pushing testosterone below the castration level within 7 to 8 days.56

Does IGF-1 LR3 increase testosterone?

There is no evidence either way. No study reviewed here measured testosterone after IGF-1 LR3, in people or in animals; published LR3 research looked at growth, nitrogen balance and protein turnover in cells and rats.78 A ClinicalTrials.gov search in October 2026 found no registered human LR3 trial.9 Mecasermin (Increlex), an FDA-approved form of IGF-1, is indicated for growth failure in children 2 years and older with severe primary IGF-1 deficiency.10

Does sermorelin mess with your testosterone?

No sermorelin-only study reviewed here reports a change in testosterone.1112 In a chart review of 14 men already on testosterone therapy who added a combination of sermorelin, GHRP-2 and GHRP-6, LH, FSH and estradiol did not change significantly; testosterone rose, but every man was taking testosterone.11 In a 1992 trial, older men started with lower testosterone than young men, and no change with treatment was reported.12

Can hCG keep testosterone up during testosterone therapy?

One small study suggests it can protect testosterone inside the testes. In 29 healthy men given weekly testosterone injections for 3 weeks, testosterone inside the testes fell 94% without hCG; with one of three low hCG doses added, it ended between 25% below baseline (lowest dose) and 26% above it (highest dose).1314 For restarting natural testosterone after anabolic steroid use, a 2014 review planned as a meta-analysis found no quality studies that met its criteria.15 hCG is a prescription drug, and the prescriber sets the dose.16

Written by D2C Peptides Editorial Team.

Pending qualified review.

Updated .

Sources

  1. Kisspeptin-10 is a potent stimulator of LH and increases pulse frequency in men (George et al.): 22.5-hour infusion. Journal of Clinical Endocrinology and Metabolism (PMC), 2011.
  2. Exploring the pathophysiology of hypogonadism in men with type 2 diabetes: kisspeptin-10 stimulates serum testosterone and LH secretion in men with type 2 diabetes and mild biochemical hypogonadism (George et al.). Clinical Endocrinology (PubMed record via NCBI E-utilities), 2013.
  3. The effects of kisspeptin-10 on reproductive hormone release show sexual dimorphism in humans (Jayasena et al.): testosterone and sex differences. Journal of Clinical Endocrinology and Metabolism (PMC), 2011.
  4. Effects of Kisspeptin on Sexual Brain Processing and Penile Tumescence in Men With Hypoactive Sexual Desire Disorder (Mills et al.): full text. JAMA Network Open (PMC), 2023.
  5. Double-blind, randomized, placebo-controlled study of safety, tolerability, pharmacokinetics and pharmacodynamics of TAK-683, an investigational metastin analogue in healthy men (Scott et al.): results. British Journal of Clinical Pharmacology (PMC), 2013.
  6. Sustained exposure to the investigational Kisspeptin analog, TAK-448, down-regulates testosterone into the castration range in healthy males and in patients with prostate cancer: results from two phase 1 studies (MacLean et al.), abstract: results. Journal of Clinical Endocrinology and Metabolism (PubMed record via NCBI E-utilities), 2014.
  7. Anabolic effects of insulin-like growth factor-I (IGF-I) and an IGF-I variant in normal female rats (Tomas et al.), abstract: design and effects. Journal of Endocrinology (PubMed PMID 8371075), 1993.
  8. Francis et al. 1992, abstract: potency in L6 myoblasts. Journal of Molecular Endocrinology (PubMed PMID 1378742), 1992.
  9. ClinicalTrials.gov API query: all fields for 'IGF-1 LR3', 'Long R3 IGF-I', 'LR3 IGF-1', 'Long R3 IGF-1' or 'LongR3' (run October 24, 2026). ClinicalTrials.gov, U.S. National Library of Medicine, 2026.
  10. INCRELEX (mecasermin) injection, prescribing information revised 07/2025: Highlights, Indications and Usage. U.S. Food and Drug Administration (Drugs@FDA label, BLA 021839), 2025.
  11. Growth Hormone Secretagogue Treatment in Hypogonadal Men Raises Serum Insulin-Like Growth Factor-1 Levels (Sigalos et al.), full text. Am J Mens Health (PMC full text PMC5675260), 2017.
  12. Growth hormone (GH)-releasing hormone-(1-29) twice daily reverses the decreased GH and insulin-like growth factor-I levels in old men (Corpas et al.), safety and baseline hormones. J Clin Endocrinol Metab (PubMed abstract PMID 1379256, via NCBI E-utilities), 1992.
  13. Coviello AD et al. Low-dose human chorionic gonadotropin maintains intratesticular testosterone in normal men with testosterone-induced gonadotropin suppression. J Clin Endocrinol Metab 2005;90(5):2595-602 (PMID 15713727), suppression. Journal of Clinical Endocrinology and Metabolism (PubMed record via NCBI E-utilities), 2005.
  14. Same source as 13: results.
  15. Rahnema CD et al. Anabolic steroid-induced hypogonadism: diagnosis and treatment. Fertil Steril 2014;101(5):1271-9 (PMID 24636400), design. Fertility and Sterility (PubMed record via NCBI E-utilities), 2014.
  16. Pregnyl (chorionic gonadotropin) for injection, prescribing information revised 3/2023: Indications and Usage. U.S. Food and Drug Administration, Drugs@FDA label (BLA 017692, Organon), 2023.
  17. The kisspeptin-GnRH pathway in human reproductive health and disease (Skorupskaite, George, Anderson). Human Reproduction Update (PMC), 2014.
  18. Same source as 16: Clinical Pharmacology.
  19. Same source as 16: Clinical Pharmacology (gonadal steroids).
  20. KISS1_HUMAN (Q15726): Metastasis-suppressor KiSS-1, peptide features. UniProt Consortium (UniProtKB/Swiss-Prot), 2026.
  21. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (Kisspeptin-10 entry). U.S. Food and Drug Administration, 2026.
  22. Gonadorelin (CID 638793): record description (ChEBI, DrugBank, NCI Thesaurus). PubChem, NIH/NLM, 2026.
  23. The Pulsatile Gonadorelin Pump Induces Earlier Spermatogenesis Than Cyclical Gonadotropin Therapy in Congenital Hypogonadotropic Hypogonadism Men (Zhang L et al.; PMC6775549), full text. American Journal of Men's Health, 2019.
  24. The Pulsatile Gonadorelin Pump Induces Earlier Spermatogenesis Than Cyclical Gonadotropin Therapy in Congenital Hypogonadotropic Hypogonadism Men (Zhang L et al.; PMID 30569789), abstract. American Journal of Men's Health, 2019.
  25. Hypophysial responses to continuous and intermittent delivery of hypothalamic gonadotropin-releasing hormone (Belchetz PE et al.; PMID 100883). Science, 1978.
  26. Drugs@FDA data: applications with active ingredient gonadorelin. U.S. Food and Drug Administration (openFDA), 2026.
  27. FDA notice to compounders: changes that affect compounding beginning March 23, 2020 (503A and 503B). U.S. Food and Drug Administration, 2020.
  28. The 2026 Prohibited List, World Anti-Doping Code, as published in Tractatenblad 2026 nr. 25: S2.2.1. World Anti-Doping Agency list, published by the Kingdom of the Netherlands (Tractatenblad), 2026.
  29. DailyMed: MENOPUR (menotropins) kit, Ferring Pharmaceuticals Inc. (BLA021663; SPL version 47 of May 11, 2026; label text revised 5/2018). U.S. National Library of Medicine (DailyMed), 2026.
  30. Stenman UH, Hotakainen K, Alfthan H. Gonadotropins in doping: pharmacological basis and detection of illicit use. Br J Pharmacol 2008;154(3):569-83 (PMID 18414398). British Journal of Pharmacology (PubMed record via NLM E-utilities), 2008.
  31. MENOPUR (menotropins for injection) prescribing information, Patient Information and Instructions for Use, revised February 2014 (supplement 014). U.S. Food and Drug Administration, Drugs@FDA label (Ferring Pharmaceuticals Inc.), 2014.
  32. Clinical and experimental study of the peptide bioregulator Testagen (Khavinson V.Kh., Ryzhak G.A.; article in Russian). RLS Encyclopedia (Register of Medicines of Russia), rlsnet.ru, 2021.
  33. PubMed search for 'testagen'. PubMed, National Library of Medicine, 2026.
  34. DailyMed SPL search for drug name 'testagen'. DailyMed, National Library of Medicine, 2026.
  35. Raun K, et al. Ipamorelin, the first selective growth hormone secretagogue (PubMed abstract, PMID 9849822). European Journal of Endocrinology, 1998.
  36. Effect of a new synthetic hexapeptide to selectively stimulate growth hormone release in healthy human subjects (Ilson BE et al.; PMID 2543692). Journal of Clinical Endocrinology and Metabolism (abstract via NCBI PubMed E-utilities), 1989.
  37. EGRIFTA WR prescribing information: 12.2 Pharmacodynamics. U.S. Food and Drug Administration (Drugs@FDA label, BLA 022505), 2025.
  38. Beyond the androgen receptor: the role of growth hormone secretagogues in the modern management of body composition in hypogonadal males (Sinha DK et al.). Translational Andrology and Urology, 2020.
  39. PubChem Compound CID 16132413 (Sermorelin): record description from DrugBank. PubChem, NCBI, U.S. National Library of Medicine (source: DrugBank DB00010), 2026.
  40. PubChem Compound CID 16132413 (Sermorelin): mechanism of action. PubChem, NCBI, U.S. National Library of Medicine (source: DrugBank DB00010), 2026.
  41. FDA Briefing Document, Pharmacy Compounding Advisory Committee Meeting, December 4, 2024: CJC-1295-Related Bulk Drug Substances (FDA evaluation dated 11/15/2024). U.S. Food and Drug Administration, 2024.
  42. ClinicalTrials.gov API search: ipamorelin CJC-1295 (no studies returned). ClinicalTrials.gov (U.S. National Library of Medicine).
  43. FDA Briefing Document, Pharmacy Compounding Advisory Committee Meeting, October 29, 2024: Ipamorelin-Related Bulk Drug Substances (Ipamorelin (free base) and Ipamorelin Acetate), including FDA Evaluation dated 8/19/2024. U.S. Food and Drug Administration, 2024.
  44. The combined administration of GHRP-2, TRH and GnRH to men with prolonged critical illness evokes superior endocrine and metabolic effects compared to treatment with GHRP-2 alone (Van den Berghe G et al.). Clinical Endocrinology (PubMed record via NCBI E-utilities), 2002.
  45. On the in vitro and in vivo activity of a new synthetic hexapeptide that acts on the pituitary to specifically release growth hormone (Bowers CY et al.; PubMed abstract, PMID 6714155). Endocrinology (abstract via NCBI PubMed E-utilities), 1984.
  46. Same source as 21.
  47. Same source as 37: EGRIFTA WR (tesamorelin) for injection, prescribing information: 1 Indications and Usage.
  48. Meinhardt U et al. 2010 (PMID 20439575): sprint capacity. Annals of Internal Medicine, via PubMed (NCBI E-utilities), 2010.
  49. Blackman MR et al. 2002 (PMID 12425705): lean body mass in men. JAMA, via PubMed (NCBI E-utilities), 2002.
  50. GENOTROPIN prescribing information: How supplied (handling and Rx statement). U.S. Food and Drug Administration (Drugs@FDA label, Pfizer), 2025.