Head to head
Thymalin against Thymogen
A calf-thymus peptide preparation and a synthetic dipeptide derived from the same line of research. One is an extract and one is a defined molecule, which is the difference that decides what can be reproduced.
Column A
ThymalinThymalin (thymic peptide bioregulator)
A calf-thymus peptide preparation used clinically in the Soviet Union and Russia since the 1980s, with a large Russian clinical literature, a 6 to 8 year cohort reporting roughly twofold lower mortality, and a 92-patient open-label randomized COVID-19 trial. None of it has been replicated outside that tradition.
Column B
ThymogenThymogen (Glu-Trp dipeptide)
A synthetic dipeptide immune modulator derived from thymus peptide research, used in Russia to support immune function.
Side by side, on the facts we can check
| Attribute | Thymalin | Thymogen |
|---|---|---|
| Category | Immune | Immune |
| FDA status | Not FDA-approved. Not among the seven peptides reviewed by the FDA Pharmacy Compounding Advisory Committee in July 2026 | Not FDA-approved (used in Russia) |
| Half-life | Short | Short |
| Molecular weight | Mixture of thymic polypeptides, so no single molecular weight; the manufacturer describes a low-kilodalton fraction | 333.3 Da |
| Mechanism | Thymalin supplies a mixture of thymic signalling peptides intended to substitute for the falling output of the involuting thymus. In cultured human hematopoietic stem cells it reduced the stem marker CD44 and the intermediate marker CD117 2 to 3-fold and raised CD28, a marker of mature T lymphocytes, 6.8-fold, which the authors read as a push toward mature T-cell differentiation. Two dipeptides are proposed as its active components: Lys-Glu, reported to activate macrophages, lymphocytes, thymocytes and neutrophils, and Glu-Trp, which was isolated from Thymalin by reversed-phase HPLC in the 1990s and developed separately as the drug Thymogen. Because Thymalin is an extract rather than a defined molecule, batch composition is not fixed, and no single molecular weight or potency unit describes it. | Proposed to modulate T-cell function and immune regulation as a minimal active fragment of thymic peptides. |
| Human studies cited | 4 | 1 |
| Legal status, US | Not approved; research use only | Not approved; research use only |
Frequently asked questions
What is the difference between Thymalin and Thymogen?
Thymalin: A calf-thymus peptide preparation used clinically in the Soviet Union and Russia since the 1980s, with a large Russian clinical literature, a 6 to 8 year cohort reporting roughly twofold lower mortality, and a 92-patient open-label randomized COVID-19 trial. None of it has been replicated outside that tradition. Thymogen: A synthetic dipeptide immune modulator derived from thymus peptide research, used in Russia to support immune function.
Which has stronger research evidence, Thymalin or Thymogen?
This database does not grade compounds. It counts what was run in people: 4 of the 8 studies cited on the Thymalin profile were human work, against 1 of 2 for Thymogen. Those counts are of our own citation lists and understate any larger literature, and neither is a recommendation.
Are Thymalin and Thymogen FDA-approved?
Thymalin: Not FDA-approved. Not among the seven peptides reviewed by the FDA Pharmacy Compounding Advisory Committee in July 2026. Thymogen: Not FDA-approved (used in Russia).
Related posts
Blog articles that cover Thymalin or Thymogen, newest first.
Reviewed Sep 2026. This page sets two published records side by side. It is educational, it is not medical advice, and it contains no dosing protocols or recommendations for personal use.