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PeptideMostly animalNot FDA approved

Testagen

Lys-Glu-Asp-Gly tetrapeptide

Last reviewed October 27, 2026 · 12 sources · Written for general readers · Compare with another compound →

The bottom line

Testagen is a four amino acid peptide from the Khavinson group, sold online for the testes and male hormones. The only animal studies of the same molecule were in chickens with the pituitary gland removed and looked at the thyroid and thymus, not the testes.[1][2] We found no study showing it raises testosterone or helps fertility, and no human studies at all.

Where the evidence stands

What it is

Testagen is the trade name for KEDG, a chain of four amino acids: lysine, glutamic acid, aspartic acid and glycine.[3] It comes from the short peptide program of Vladimir Khavinson in St. Petersburg.

Its name points to the testes, but a separate team studied the same sequence as a peptide based on the pituitary, a hormone gland under the brain, and did not use the name Testagen.[4] The newest paper using the name studied it as a way to stop copper from rusting in salt water, not as a medicine.[5]

Name
Testagen (Lys-Glu-Asp-Gly tetrapeptide)
Other names
KEDG, lysyl glutamyl aspartyl glycine
Type
Peptide
Sequence
KEDG

How it works

The group says Testagen, like its other short peptides, binds DNA and the proteins DNA wraps around.

  • A tagged version of the peptide entered the nucleus of HeLa cells, a human cancer cell line, and in a test tube it bound DNA pieces with a particular letter pattern.[3]
  • KEDG and five related peptides bound histones, the proteins DNA wraps around, in test tube work.[6]
  • A review by the group lists KEDG among peptides that may guide immune cells to mature.[7]
  • A computer modeling study by the group predicted KEDG is among the peptides best carried by cell transport proteins.[8]

None of this has been linked to testis function, and the work comes from the developer's group.

What the research shows

We keep animal and human evidence apart. A result in animals is a reason to study something in people, not proof that it works in people.

Animal and lab studies

Chicken studies of the thyroid and thymus, not the testes

  • In chicks that had the pituitary gland removed at birth, KEDG given for 40 days raised thyroid stimulating hormone and thyroid hormones and helped the thyroid recover its structure.[1]
  • In young chickens and old hens with the pituitary removed, the peptide reduced hormone and thyroid damage, but the effect was weaker in old hens.[4]
  • Thyroid recovery was greater in one year old birds than in five year old birds.[9]
  • In the same chicken model, KEDG helped the thymus, a gland where immune cells mature, recover its structure, more than a related peptide did.[2]
  • Another report said it normalized immune and blood clotting measures in these birds.[10]
  • We found no study of Testagen in testis tissue, sperm or male hormones in any animal.

Limit: These are small chicken studies from one team, with no numbers in their summaries, and they did not test the testes.

Human studies

No human studies

  • We found no published clinical trials of Testagen in people.

Limit: Nobody knows whether it affects testosterone, sperm or fertility in people, or whether it is safe.

Claims check

The most common claims about this compound, and what studies actually found. Verdicts rate the evidence, not whether you should use it.

Raises testosterone

Not tested

No study has measured testosterone after Testagen in animals or people. The chicken studies measured thyroid hormones, not sex hormones.[1][4]

Improves sperm and fertility

Not tested

We found no study of sperm, testis tissue or fertility. The published work on the molecule is test tube, cell line and chicken thyroid research.[3][1]

Boosts libido and sexual function

Not tested

No study has tested sex drive or sexual function. The only animal work looked at the thyroid and thymus in chickens.[4][2]

Balances hormones

Only in animals

In chickens with the pituitary gland removed, KEDG raised thyroid stimulating hormone and thyroid hormones, with weaker effects in older birds.[1][9] These birds had a major gland removed, so the results may not apply to healthy animals or people.

Supports immunity

Only in animals

In the same chicken model, it helped the thymus recover and normalized immune measures.[2][10] A review by the group lists it among peptides that may guide immune cells to mature.[7]

Known risks and side effects

  • Unregulated products. It is sold online outside pharmacies with no FDA review, so what is in the vial or capsule, how pure it is, and how much it holds are unknown.[11]
  • No human safety data. Only chicken and lab studies exist, so side effects in people are completely unknown.[1]
  • Unproven for male hormones. Low testosterone and infertility have proven tests and treatments. No study shows Testagen changes either, and the animal work points to thyroid effects instead.[4]
  • Banned in sport. WADA bans unapproved drugs at all times, in and out of competition.[12]

Regulatory status

Today: It is not approved by the FDA for any use. It is not named on FDA's list of risky bulk substances for compounding as updated April 22, 2026.[11] WADA bans at all times any drug not approved by a government health agency for human use, so athletes should treat it as banned unless their anti doping agency says otherwise.[12]

Sources

  1. Kuznik BI, Pateyuk AV, Rusaeva NS. Effect of tetrapeptides Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly on the structure and function of the thyroid gland in neonatally hypophysectomized chickens. Bull Exp Biol Med. 2008;145(1):104-7. PMID 19024016
  2. Pateyk AV, Baranchugova LM, Rusaeva NS, Obydenko VI, Kuznik BI. Effect of peptides Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly on the morphology of the thymus in hypophysectomized young and old birds. Bull Exp Biol Med. 2013;154(5):681-5. PMID 23658898
  3. Fedoreyeva LI, Kireev II, Khavinson VKh, Vanyushin BF. Penetration of short fluorescence-labeled peptides into the nucleus in HeLa cells and in vitro specific interaction of the peptides with deoxyribooligonucleotides and DNA. Biochemistry (Mosc). 2011;76(11):1210-9. PMID 22117547
  4. Kuznik BI, Pateyuk AV, Rusaeva NS, Baranchugova LM, Obydenko VI. Effects of peptides Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly on hormonal activity and structure of the thyroid gland in hypophysectomized young chickens and old hens. Bull Exp Biol Med. 2011;150(4):495-9. PMID 22268052
  5. Dobritescu A, Samide A, Cioatera N, Mic OC, Ionescu C, Dabuleanu I, Tigae C, Spinu CI, Oprea B. The Inhibitory Effect and Adsorption Properties of Testagen Peptide on Copper Surfaces in Saline Environments: An Experimental and Computational Study. Molecules. 2025;30(15):3141. PMID 40807317
  6. Fedoreyeva LI, Smirnova TA, Kolomijtseva GYa, Khavinson VKh, Vanyushin BF. Interaction of short peptides with FITC-labeled wheat histones and their complexes with deoxyribooligonucleotides. Biochemistry (Mosc). 2013;78(2):166-75. PMID 23581987
  7. Khavinson V, Linkova N, Diatlova A, Trofimova S. Peptide Regulation of Cell Differentiation. Stem Cell Rev Rep. 2020;16(1):118-125. PMID 31808038
  8. Khavinson VK, Linkova NS, Rudskoy AI, Petukhov MG. Feasibility of Transport of 26 Biologically Active Ultrashort Peptides via LAT and PEPT Family Transporters. Biomolecules. 2023;13(3):552. PMID 36979488
  9. Kuznik BI, Pateiuk AV, Rusaeva NS, Baranchugova LM, Obydenko VI. [Effects of Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly peptides on hormonal activity and thyroid morphology in hypophysectomized mature and old birds]. Adv Gerontol. 2011;24(1):93-8. PMID 21809626
  10. Kuznik BI, Pateiuk AV, Rusaeva NS, Baranchugova LM, Obydenko VI. [Effects of hypophyseal Lys-Glu-Asp-Gly and Ala-Glu-Asp-Gly synthetic peptides on immunity, hemostasis, morphology and functions of the thyroid gland in neonatally hypophysectomized chicken and one-year-old birds]. Patol Fiziol Eksp Ter. 2010;(1):14-8. PMID 20731122
  11. U.S. Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks. Content current as of April 22, 2026. FDA
  12. World Anti-Doping Agency. The 2026 Prohibited List, World Anti-Doping Code International Standard. In force January 1, 2026. WADA 2026
Medical disclaimer

This page is educational information only. It is not medical advice and does not replace care from a licensed medical provider. Do not use this page to decide whether to take any substance. Talk to a licensed medical provider first.

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