Section 01
What it's used for
Soviet-era reports, not trials
Thymalin has been used in Russia for immune deficiency. Old Soviet-era case reports describe it restoring immune-cell activity in patients, including after thymus removal or burns, but these were not controlled trials or T-cell counts.
▸Clinical wording
Thymalin has been used clinically in Russia for immunodeficiency states. Small, uncontrolled case series and reports from the Soviet era describe thymalin restoring T-lymphocyte functional activity in patients with immunodeficiency, including post-thymectomy and burn patients, but these are not controlled trials and do not report T-cell counts specifically. No publication was found supporting a claim of improved vaccine responses.
A 2003 study tracked mortality
A 2003 study followed 266 elderly people for 6-8 years. Thymalin alone was linked to about 2.0-2.1x lower mortality than untreated controls. Combined with epithalamin, this reached 2.5-fold after 2-3 years, rising to 4.1-fold after 6 years.
▸Clinical wording
A 2003 human follow-up study by Khavinson and colleagues followed 266 elderly patients for 6-8 years and found that thymalin alone was associated with an approximately 2.0- to 2.1-fold reduction in mortality compared with untreated controls, while the combined thymalin-plus-epithalamin regimen showed a larger effect: 2.5-fold reduction after an initial 2-3 year course, rising to 4.1-fold when treatment continued annually for 6 years. Describing the combined 6-year regimen as producing only a "2-fold reduction in mortality" understates what the paper reports.
One small cancer study, chemo only
In one study of 44 kidney and bladder cancer patients, adding thymalin to chemotherapy partly normalized immune markers, not fully to healthy levels. No study combined thymalin with radiation; broader claims go beyond this limited evidence.
▸Clinical wording
A single small human study (n=44) evaluated thymalin combined with chemotherapy in patients with kidney and bladder cancer and found partial normalization of lymphocyte antigen expression, though the authors noted these values did not fully reach levels seen in healthy subjects. No publication combining thymalin with radiation therapy was found, and the broader claim of "improved immune reconstitution and reduced infectious complications" across Russian oncology practice is not supported by this limited evidence.
Section 02
Mechanism of Action
An extract, not one single molecule
- Thymalin is a mixture extracted from calf thymus rather than one defined molecule.
- Three very short peptides have been isolated from that mixture.
- Reports from the originating group say these peptides dock onto DNA and its packaging proteins (histones).
- The route from that docking to changed gene activity is proposed and computer-modelled, not proven.
▸Clinical wording
Short regulatory peptides acting on DNA and histones
Thymalin is a polypeptide complex extracted from calf thymus rather than a single defined molecule. Three short peptides have been isolated from it: the dipeptides Glu-Trp and Lys-Glu and the tripeptide Glu-Asp-Pro. Reviews from the originating group report that Lys-Glu binds double-stranded DNA selectively at TCGA sequences and that these peptides dock preferentially onto histones H1, H2b, H3 and H4 at their DNA-contact sites. Separate docking work placed Glu-Trp on GGAG motifs in B-form DNA and Lys-Glu on GCGC motifs in nucleosomal curved DNA, both via minor-groove hydrogen bonds. This remains a proposed, computationally supported route to altered transcription.
Steering immature immune cells in rodents
- The thymus effects are credited to the short dipeptides, on rodent and cell-culture evidence.
- One dipeptide is reported to push thymus cells toward the helper T-cell lineage and activate immune cells.
- In an irradiation model of accelerated ageing, a tripeptide preserved thymus structure and raised cell proliferation.
- This evidence is summarised by the group that originated the peptide, not by independent laboratories.
▸Clinical wording
Thymocyte maturation and the thymic microenvironment
Thymus-directed activity is attributed by the originating group to the component dipeptides, on rodent and cell-culture evidence summarised in their review. Lys-Glu is reported to induce CD4 and CD5 expression on thymic cells, shifting differentiation toward the T-helper lineage, and to have an activating effect on macrophages, blood lymphocytes, thymocytes and neutrophils. In a gamma-irradiation model of accelerated ageing, the tripeptide Glu-Asp-Pro preserved the cortex-medulla boundary of the thymus and increased thymocyte proliferation scored by PCNA alongside macrophage and mast-cell counts.
Pushing stem cells toward mature T cells
- In human blood stem cell culture, immature markers fell while a mature T-cell marker rose 6.8-fold.
- The authors read that as progenitor cells progressing toward mature T lymphocytes.
- In a single-blind randomised trial in older COVID-19 patients (36 treated, 44 controls), lymphocyte counts roughly doubled.
- Helper and killer T-cell counts rose 2.2-fold and natural killer cells 2.4-fold in that trial.
▸Clinical wording
Progenitor differentiation and lymphocyte recovery
In human haematopoietic stem cell culture, thymalin lowered the stem and intermediate markers CD44 and CD117 two- to three-fold while raising CD28, a mature T-lymphocyte marker, 6.8-fold, which the authors interpret as progression of CD117+ cells toward mature T lymphocytes. In a single-blind randomised trial in older patients with severe COVID-19 (36 treated, 44 controls), the thymalin arm showed roughly a doubling of blood lymphocytes, 2.2-fold rises in CD4+ and CD8+ counts, a 3.4-fold rise in CD3+HLA-DR+ cells, a 2.4-fold rise in NK cells, and a CD4/CD8 ratio moving from 1.15 to 1.25.
Quieting the alarm signals of immune cells
- In human blood cells triggered by bacterial toxin, two inflammation messengers fell about two- to threefold.
- The isolated dipeptides acted more selectively, one cutting TNF-alpha roughly sixfold and IL-6 about 2.5-fold.
- In a macrophage cell line the extract also lowered messenger release and raised adhesion to vessel lining.
- In the clinical series above, circulating IL-6 fell 6.5-fold and the inflammation marker CRP 3.3-fold.
▸Clinical wording
Damping of monocyte and macrophage cytokine output
In human peripheral blood mononuclear cells stimulated with lipopolysaccharide, thymalin reduced TNF-alpha about 2.2-fold and IL-1beta about 2.7-fold by ELISA, while the isolated dipeptides acted more selectively, Lys-Glu cutting TNF-alpha roughly six-fold and IL-6 about 2.5-fold. In PMA-differentiated THP-1 macrophages challenged with LPS, thymalin likewise lowered TNF-alpha and IL-6 release, raised monocyte growth rate and extracellular vesicle output, and, unlike the other peptides tested, increased monocyte adhesion to activated endothelium. In the clinical series above, circulating IL-6 fell 6.5-fold and CRP 3.3-fold.
Section 03
Biological Pathways
- DNA/Histone-Binding PeptidesThymalin's isolated dipeptides Glu-Trp and Lys-Glu are reported to bind double-stranded DNA at specific motifs and dock onto histones H1, H2b, H3, and H4, a proposed route to altered transcription.
- Thymocyte Maturation & Thymic MicroenvironmentLys-Glu is reported to induce CD4 and CD5 expression, shifting differentiation toward the T-helper lineage, while Glu-Asp-Pro preserved thymic cortex-medulla structure in an aging model.
- Progenitor Differentiation & Lymphocyte RecoveryIn stem cell culture, thymalin lowered CD44/CD117 progenitor markers while raising the mature marker CD28; in a COVID-19 trial it roughly doubled blood lymphocyte counts and shifted the CD4/CD8 ratio.
- Cytokine Dampening in Monocytes/MacrophagesThymalin reduced TNF-alpha and IL-1beta release from LPS-stimulated blood cells and lowered macrophage TNF-alpha/IL-6 output; in the same trial, circulating IL-6 fell 6.5-fold and CRP 3.3-fold.
Section 04
Dosage Information
| Route / system | Context | Range studied | Limitation |
|---|---|---|---|
| Intramuscular — registered label | Russian label, weak immunity after infection or chemo | Adults 5–20 mg daily or every other day for 3–10 days, 30–100 mg per course, repeatable after 1–6 months; children 1–5 mg by age. | The active ingredient is calf thymus extract — a mixture, not one molecule, so these milligrams do not compare with milligrams of synthetic thymosin alpha-1. |
| Intramuscular — COVID-19 study | One randomised study, severe COVID-19 in older adults | 10 mg in 2 mL of saline once a day for 10 days: 36 patients on standard care plus Thymalin, 44 on standard care plus placebo. | Eighty patients at one centre, from the drug's own developers and never repeated. Treating severe illness in hospital says nothing about prevention. |
| Intramuscular — anti-ageing programme | The developers' own 6–8 year follow-up, adults over 60 | Repeated yearly courses in 266 people over 60, some also on Epithalamin; the published summary gives no dose in milligrams at all. | Mortality is reported 2.0–2.1 times lower on Thymalin and 4.1 times lower on the six-year combination — unblinded, run by its creators, never repeated. |
| Subcutaneous or intramuscular — practice | Circulating practice, outside label and trials | 10 mg once a day for 5–10 days, courses repeated once or twice a year — about 110–140 µg/kg of extract a day for a 70–90 kg adult. | Practice settled on 10 mg because that is the vial sold, while the label allows 5–20 mg. It is weighed extract: the same figure from two makers can differ. |
Results
Syringe Fill Level (100u syringe)
Set positive values for: Recommended dose per kg.
Research Use Only. This information is for educational and research purposes only. Not intended for medical advice or self-medication.
Section 05
Protocols
No protocols featuring this peptide yet. Browse All Protocols
Section 06
Stability & Storage
Lyophilised powder
Supplied as a lyophilised powder for injection in 10 mg vials, stored at 2–8 °C, with a shelf life of 3 years. Before intramuscular injection it is reconstituted with isotonic saline.
After reconstitution
The saline solution is prepared right before the intramuscular injection and is not intended to be stored; no extended in-use period is established for it.
Section 07
Side Effects & Precautions
Generally well-tolerated over decades of clinical use. Rare allergic reactions. Mild injection site pain. No significant adverse effects documented in clinical studies spanning thousands of patients.
Section 08
Regulatory Status
Russia
Approved medicine since 1977
Thymalin was developed by Khavinson and Morozov at the Military Medical Academy and authorised for clinical use under the Russian Ministry of Health; it is still produced by the St. Petersburg Institute of Bioregulation and Gerontology and used clinically as an immunomodulator.
CIS countries
Registered in several states
Beyond Russia, Thymalin holds marketing authorisation in a number of former Soviet states that recognise Russian pharmacopoeia registrations; that recognition does not extend to Western regulators.
FDA & EMA
Not approved
Thymalin has no FDA or EMA marketing authorisation and has not been reviewed as a drug in the US or EU; there it circulates only as an unregulated research compound, outside any pharmaceutical oversight.
WADA
Not on the Prohibited List
Thymalin itself is not named in WADA's 2026 Prohibited List. The list does prohibit a different thymic peptide, Thymosin-ß4 and its derivatives (e.g. TB-500), under S2 — the two should not be confused.
A Russian Ministry of Health registration is a real approval, but it does not carry over to other countries, and WADA silence on Thymalin by name is not the same as a guarantee for every jurisdiction or future list. Check the current rules where you are.
Section 09
Research Studies
- [1]The use of Thymalin for immunocorrection and molecular aspects of biological activityKhavinson VK, Linkova NS, Chalisova NI, Ivko OM · Biology Bulletin Reviews · 2021
- [2]The influence of KE and EW dipeptides in the composition of the Thymalin drug on gene expression and protein synthesis involved in the pathogenesis of COVID-19Linkova N, Khavinson V, Diatlova A, Petukhov M, Vladimirova E, Sukhareva M, Ilina A · International Journal of Molecular Sciences · 2023
- [3]Thymalin: activation of differentiation of human hematopoietic stem cellsKhavinson VK, Linkova NS, Kvetnoy IM, Polyakova VO, Drobintseva AO, Kvetnaia TV, Ivko OM · Bulletin of Experimental Biology and Medicine · 2020
- [4]Peptide drug Thymalin regulates immune status in severe COVID-19 older patientsKuznik B, Khavinson V, Shapovalov K, Linkova N, Lukyanov S, Smolyakov Y, Tereshkov P, Shapovalov Y, Konnov V, Tsybikov N · Advances in Gerontology · 2021
- [5]Peptides regulating proliferative activity and inflammatory pathways in the monocyte/macrophage THP-1 cell lineAvolio F, Martinotti S, Khavinson VK, Esposito JE, Giambuzzi G, Marino A, Mironova E, Pulcini R, Robuffo I, Bologna G, Simeone P, Lanuti P, Guarnieri S, Trofimova S, Procopio AD, Toniato E · International Journal of Molecular Sciences · 2022
Section 10
Frequently Asked Questions
Thymalin is a polypeptide complex extracted from calf thymus, not a single defined molecule — its active fragments include the dipeptides Glu-Trp and Lys-Glu. It has been an approved immunomodulatory medication in Russia and several CIS countries for decades, used for immunodeficiency after infection, surgery or chemotherapy. It is not approved by the FDA or EMA and is treated as a research compound in Western countries.
The strongest human evidence is a single randomized trial: 36 older patients with severe COVID-19 got thymalin alongside standard care, 44 got placebo, and the treated group showed roughly double the lymphocyte count and 2.2-fold higher CD4+ and CD8+ counts. That trial was run at one center by the drug's own developers and has not been independently replicated; the rest of the human record is uncontrolled case reports from Soviet-era practice.
The Russian label allows 5 to 20 mg a day or every other day for 3 to 10 days, repeatable after 1 to 6 months. The one controlled trial used 10 mg a day for 10 days, and outside-trial practice tends to copy that same 10 mg figure mainly because that is the size of the vial sold, not because it was tested against other doses.
No. Thymalin is a mixture of short peptides extracted from calf thymus tissue, while thymosin alpha-1 is a single, chemically defined 28-amino-acid peptide (thymalfasin) approved in over 35 countries. Their milligram doses are not comparable because one is a purified compound and the other is a weighed extract that can vary between manufacturers.
The claim traces to one open-label follow-up by thymalin's own developers: 266 people over 60 given repeated yearly courses, with mortality reported 2.0 to 2.1 times lower on thymalin alone and up to 4.1 times lower on a six-year combination with another peptide. The study was unblinded, run by the people who created the drug, and has never been repeated by an independent group, so it does not establish a longevity effect.
The documented profile is mild — rare allergic reactions and injection-site pain are the main reports across decades of Russian clinical use. That record comes mostly from case-series style reporting rather than Western-style controlled trials; the only randomized trial run on it, in severe COVID-19, did not report new safety signals in 36 treated patients.
It is an approved prescription medication in Russia and several CIS countries, but it has no FDA or EMA approval and no path through Western regulatory review has been reported. In the US and similar markets it is sold and used only as a research compound.