Thymalin
An injectable polypeptide complex extracted from calf thymus and sold as an immune bioregulator. It is a mixture, not a molecule: the 2023 paper from its own developers describes it as a polypeptide extract of thymus whose activity is attributed to dipeptide fractions. There is no single amino-acid sequence for it, and this entry deliberately prints none. Many vendor pages and chemical databases print one anyway. Its human evidence is a long-running non-randomised course programme run by the institute that developed it.
This is a peptide complex. It contains many peptides and has no single sequence — printing one would be fabrication.
Bioregulator context
Target tissue: thymus (immune)
That a peptide fraction isolated from young thymic tissue restores age-related decline in immune function, and that annual courses of it in people over 60 lower the incidence of age-related disease and mortality. The developers further state that the preparation's activity is carried by short dipeptide fragments within the extract rather than by any single characterised molecule.
Proposed to act through short dipeptides present in the extract, which are in turn proposed to reach the nucleus and modulate transcription by binding DNA. The 2023 developer paper supports this with molecular docking plus a cytokine assay in cultured human mononuclear cells — modelling and a dish, not a demonstrated regulatory event in a person.
Mechanism
Claimed
Restores immune function in ageing, protects against age-related disease, and lowers mortality when taken as repeated annual courses.
Actually established
In cultured human mononuclear cells, Thymalin and its two named dipeptide fractions reduced IL-1β, IL-6 and TNF-α output, and in cultured human haematopoietic stem cells it shifted surface-marker expression toward a mature T-lymphocyte profile. Nothing about how it produces a clinical effect in a person has been established, and for a mixture the question is partly unanswerable: the entity whose mechanism would be described has no fixed composition.
How good is the evidence
PubMed indexed 293 records mentioning Thymalin when checked on 2026-08-06, which makes it one of the better-documented substances in this family — but the documentation is concentrated. The headline human result is a 266-subject, 6-8 year course programme reported by the compound's developer in a Russian-language gerontology journal, with no randomisation described and no independent replication. A 2022 Russian COVID-19 comparison reports lower hospital mortality with Thymalin, and prints different mortality figures in its own English and Russian abstracts. The cell work is developer-authored. The only work here with no link to the originating institute is rodent bone-healing research from a Ukrainian group and a rat sarcoma study from Rostov.
Every human result on this page comes from a Russian-language paper, and the geroprotection programme that the compound's reputation rests on lists its developer as first author and was run at the institute that produces it. The independent work that exists is animal work on unrelated endpoints (bone healing, transplanted sarcoma) — nobody outside the originating collaboration has attempted the ageing or mortality result.
Claims, one at a time
Each claim carries its own evidence tier. A compound is never simply "well studied" — some of its claims may be, others not at all.
| Claim | Verdict | Evidence | Basis |
|---|---|---|---|
| Thymalin is a thymic peptide with a defined amino-acid sequence | contradicted | In vitro | Both developer-authored papers read for this entry describe Thymalin as a polypeptide complex or extract of thymus, with activity attributed to dipeptide fractions within it — not as a single molecule. A mixture has no sequence to print. The name also collides with thymulin, a genuinely defined thymic nonapeptide, and a database lookup on the name returns thymulin's record: that collision is the likely origin of the sequences that circulate for Thymalin online. |
| Repeated courses in people over 60 reduce age-related disease and mortality | mixed | Human trial | One report covering 266 elderly subjects over 6-8 years describes a 2.0-2.1-fold lower mortality rate in the Thymalin group versus control, alongside reduced respiratory-illness incidence. It is the compound's central claim and its weakest link simultaneously: the first author is the compound's developer, the work was done at the institute that produces it, PubMed classifies the paper as a review rather than a primary trial report, no randomisation or blinding is described, the paper is in Russian and only its English abstract was read here, and no group unconnected to that collaboration has ever attempted the result. |
| Improves outcomes in severe COVID-19 | mixed | Observational | A three-group comparison in hospitalised severe COVID-19 patients reports hospital mortality of 20.6% with Thymalin against 40.9% on standard therapy — but the same paper's Russian-language abstract prints 16.2% for the Thymalin group where the English abstract prints 20.6%, an internal discrepancy that is itself the finding a reader should weigh. Allocation is not described, so it is not established that the groups were comparable. Supporting cell work exists, but a cytokine reduction in a dish is not a clinical outcome. |
| Restores T-cell immunity | mixed | In vitro | In cultured human haematopoietic stem cells, CD44 and CD117 expression fell 2-3 fold while CD28 rose 6.8 fold, which the developer-authored paper reads as stimulated differentiation into mature T lymphocytes. It is a marker-expression change in a dish, inferred rather than measured as differentiation, and no human immune endpoint has been measured against it. |
| Has antitumour activity | mixed | Animal | In outbred rats with transplanted sarcoma 45, tumour growth arrest or regression was reported in more than half of the animals, with 78% growth suppression in the rest, by a Rostov oncology group with no apparent link to the originating institute. A transplanted rodent sarcoma is a weak model for human cancer in either direction, the comparison group is not described in the abstract, and the finding has not been repeated. |
The studies themselves
| Study | Design | Subjects | Quality |
|---|---|---|---|
[Geroprotective effect of thymalin and epithalamin]
Khavinson VKh, Morozov VG · Advances in gerontology = Uspekhi gerontologii · 2002
PMID 12577695
ru |
narrative_review / human | 266 — Elderly and older persons assessed by the St Petersburg Institute of Bioregulation and Gerontology and the Institute of Gerontology, Kiev; bioregulators applied during the first 2-3 years of a 6-8 year observation | Human trial
risk of bias: high
authored by the developer |
[Morphological compound and indicators of the blood clotting system in severe COVID-19 patients of middle aged and elderly during treatment of Tocilizumab and Thymalin.]
Kuznik BI, Shapovalov KG, Smolyakov YN, Lukyanov SA, Tereshkov PP, Kazantseva LS, Linkova NS · Advances in gerontology = Uspekhi gerontologii · 2022
PMID 36169363
ru |
observational / human | — Hospitalised severe COVID-19 patients, middle-aged and elderly, Chita, Russia; three groups (basic therapy, basic therapy plus tocilizumab, basic therapy plus Thymalin). Group sizes are not stated in the abstract. | Observational
risk of bias: high
authored by the developer |
Thymalin: Activation of Differentiation of Human Hematopoietic Stem Cells
Khavinson VK, Linkova NS, Kvetnoy IM, Polyakova VO, Drobintseva AO, Kvetnaia TV, Ivko OM · Bulletin of experimental biology and medicine · 2020
PMID 33237528
|
in_vitro / cell_culture | — Human haematopoietic stem cells in culture | In vitro
risk of bias: high
authored by the developer |
Effect of Thymalin on the Tumor and Thymus under Conditions of Activation Therapy In Vivo
Zhukova GV, Schikhlyarova AI, Barteneva TA, Shevchenko AN, Zakharyuta FM · Bulletin of experimental biology and medicine · 2018
PMID 29797130
|
animal_uncontrolled / rat | — Albino outbred male rats with transplanted sarcoma 45 | Animal
risk of bias: high
|
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-19
Linkova N, Khavinson V, Diatlova A, Petukhov M, Vladimirova E, Sukhareva M, Ilina A · International journal of molecular sciences · 2023
PMID 37686182
|
in_vitro / cell_culture | 4 — Human peripheral blood mononuclear cells from four donors, LPS-induced inflammation model; plus molecular docking against double-stranded DNA and database/pathway analysis | In vitro
risk of bias: high
authored by the developer |
Expression features of T-lymphocytes, B-lymphocytes and macrophages in the post-traumatic regenerate of the mandible rats under conditions of filling a bone defect with hydroxyapatite-containing osteotropic material and thymalin injecting the surrounding soft tissues
Boiko AA, Malanchuk VA, Myroshnychenko MS, Markovska OV, Shapkin AS, Marakushyn DI · Polski merkuriusz lekarski : organ Polskiego Towarzystwa Lekarskiego · 2024
PMID 38642352
|
animal_uncontrolled / rat | — Rats with a surgically created mandibular bone defect | Animal
risk of bias: unclear
|
- Thymalin has no single amino-acid sequence. It is a mixture, and no source publishes its composition in a form that would let a reader verify what is in a given batch.
- Vendor pages and chemical databases print a sequence for it anyway. A database lookup on the name returns the record for thymulin — a different, defined nonapeptide — and the codex resolver rejected that record on 2026-08-06 on a formula mismatch.
- No randomised controlled trial of Thymalin exists in the PubMed-indexed literature, in any language, for any indication.
- The 266-subject geroprotection programme has never been attempted by any group unconnected to the institute that developed the preparation.
- No human pharmacokinetic data exists, and for a mixture the term has no single meaning: there is no one molecule whose absorption or clearance could be measured.
- The full texts of the Russian-language human studies have not been read for this entry — only their English abstracts, one of which disagrees with its own Russian counterpart on the headline mortality figure.
- No dose is recorded on any study on this page, because no full text has been read.
What people actually report
- personal reports about immune-system changes
- discussion of adaptive immunity in COVID-19 care
- interest in immune modulation for persistent infections
- longevity claims involving immune aging
- pairing with Epitalon or Pinealon
What people keep asking
- What immune-system changes have users reported?
- What evidence is discussed for adaptive immunity in COVID-19?
- Could Thymalin affect persistent infection-related symptoms?
- Why is Thymalin discussed alongside Epitalon and Pinealon?