Thymalin

Thymalinum, thymus extract peptides; the synthetic dipeptide version is Thymogen (Glu-Trp) and the Khavinson analogue is Vilon (Lys-Glu)

Immune & bioregulators

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Summary

Class: A mixture of short peptides extracted from calf thymus (not a single defined molecule); developed in the Soviet Union in the 1970s–80s. Belongs to the "Khavinson bioregulator" family
Mechanism: Proposed to restore T-cell maturation and balance immune function, and — per the bioregulator hypothesis — to influence gene expression in thymus and immune cells; mechanism is poorly characterised by Western standards
Routes studied: Intramuscular injection (Russian clinical use); oral capsule forms of related thymus peptides; community subcutaneous and intramuscular
Dose range reported: Russian label: 5–20 mg intramuscular daily for 3–10 days, repeated after 1–6 months. Community: 10 mg/day for 10 days, once or twice a year, as a "course". No validated dose outside Russian/CIS practice
Half-life: Unknown; as a peptide mixture it has no single pharmacokinetic profile
Storage: Lyophilised: refrigerate, protect from light. Reconstituted: use promptly; community practice is refrigerate and use within days to a few weeks
Regulatory status: Registered medicine in Russia and some CIS countries; not approved in the US, EU, UK, Australia or South Africa. See region table

Doses are as reported in studies or by the community — never recommendations.

1What it is

Thymalin is one of the original "peptide bioregulators" developed by Vladimir Khavinson and colleagues at the Military Medical Academy in Leningrad, starting in the 1970s. It is made by extracting low-molecular-weight peptides from calf thymus with acetic acid. Unlike thymosin alpha-1, which is a single defined 28-amino-acid molecule, thymalin is a mixture whose exact composition varies by batch. The group later identified short synthetic dipeptides they regard as the active principle — Thymogen (Glu-Trp) and Vilon (Lys-Glu).

It has been registered as a medicine in Russia since 1982 for immune deficiency states: after infections, surgery, radiotherapy or chemotherapy, and in chronic infections. Almost all the research is from the Khavinson group and related Russian institutions, published largely in Russian-language journals, with limited translation and limited independent replication. That is the central caveat for every claim below.

The most striking claim — reduced mortality in elderly people given periodic thymalin and epitalon courses over 6–12 years — comes from a St Petersburg study described in English (Khavinson & Morozov 2003), but its design (allocation method, blinding, controls) is not reported to a standard that allows the result to be graded above B.

2How it's thought to work

T-cell restoration. reported to increase T-lymphocyte counts and the CD4/CD8 ratio in people with low counts, and to promote maturation of T-cell precursors — analogous to thymosin fraction 5, from which thymosin alpha-1 was later purified.

Cytokine effects. reported to raise IL-2 and interferon production in immune-deficient states and to reduce excessive pro-inflammatory cytokines in others.

Bioregulator hypothesis. Khavinson proposes that short peptides enter cells, bind DNA at specific promoter regions and alter gene expression in a tissue-specific way, which is why thymus-derived peptides act on the immune system and pineal peptides on the pineal gland. There is some in-vitro work (molecular modelling, gene-expression changes in cell culture) but this remains a hypothesis, not an established mechanism.

Haemostasis and tissue repair. reported effects on blood coagulation and wound healing in animal models.

Proposed: a peptide fraction from calf thymus, used in Russia as an immune modulator. The trials supporting it are old and not independently repeated.Schematic — not to scale

3What the research shows

Immune deficiency after illness, surgery or cancer treatment

Russian clinical reports over decades describe improved lymphocyte counts and reduced infectious complications with thymalin courses. Most are open-label, uncontrolled or historically controlled, and published in Russian. A few English-language summaries exist (Khavinson 2002, Neuroendocrinol Lett review). [2]

Mortality and "geroprotection" in the elderly

In a long-term St Petersburg study, groups of elderly people (60–74 at entry) received thymalin, epitalon or both as short courses every 6 months for 6–12 years, and were compared with a control group. The treated groups reported fewer acute respiratory infections, improved immune and metabolic markers, and roughly halved mortality over the follow-up (Khavinson & Morozov 2003, Neuroendocrinol Lett). The design is not described in enough detail to rule out selection or ascertainment bias, and it has not been replicated outside the group. [1]

Graded B/C

Immunosenescence (age-related immune decline)

Reports of normalised T-cell subsets and improved vaccine-type responses in older people, and of restored thymus-dependent immunity in aged animals.

Graded C/D

Thymogen / Vilon dipeptides

The synthetic dipeptides have more mechanistic data (cell culture, rodent immune and lifespan studies), including modest lifespan extension in some mouse strains and reduced tumour incidence in others. Human data is limited to Russian clinical use.

Infection, sepsis and post-operative recovery (Russian clinical use)

Russian surgical and infectious-disease literature describes shorter recovery and fewer septic complications when thymalin courses were added to standard care after major surgery, burns and in chronic infections. These are mostly open or historically controlled series and have not been reproduced outside Russia and the CIS.

Any Western-standard RCT

None. There is no randomised, double-blind, placebo-controlled trial of thymalin registered or published in an indexed English-language journal.

4Reported side effects and interactions

Literature-reported

Russian prescribing information lists allergic reactions as the main adverse effect and contraindicates use in pregnancy and in atopic bronchial asthma. Decades of clinical use in Russia without a prominent safety signal, but with limited formal pharmacovigilance.

Community-reported

injection-site soreness ( route), mild fatigue or flu-like feeling in the first 1–3 days of a course, occasional headache. Some report fewer colds in the following months; this is anecdotal.

Theoretical. as an animal-derived extract, batch variability, allergic sensitisation and, in principle, contamination are concerns that do not apply to a defined synthetic peptide. The same immune-stimulation cautions as thymosin alpha-1 apply (autoimmune disease, transplant recipients), with less data to reassure.

Interactions. none documented. Immunosuppressants oppose its intended action in principle.

Markers researchers commonly monitor

Marker	Why it's watched
CBC with differential and absolute lymphocyte count	the direct target; the Russian literature reports normalisation of low counts.
Lymphocyte subsets (CD4, CD8, CD4/CD8 ratio, NK cells)	the markers used in the St Petersburg studies.
Immunoglobulins (IgG, IgA, IgM)	reported to shift toward normal in deficiency states.
CRP	general inflammation; also a flag for any adverse immune activation.
Allergy history and skin reaction at injection site	allergic reaction is the listed adverse effect of an animal-derived extract.

Free for everyone. Safety information is never behind a paywall.

5Reconstitution and handling

Supplied in Russian-market presentations as 10 mg vials for use, with 1–2 ml of isotonic saline per the label; research-market vials are also commonly 10 mg. Because it is a mixture, "concentration" refers to total peptide weight, not a single molecule.

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6Commonly studied alongside

Epitalon (the paired "thymus + pineal" course in the Khavinson longevity studies), Vilon and Thymogen (related dipeptides), thymosin alpha-1 (community comparison or combination; no combined study), pinealon and other organ-specific bioregulators.

Informational cross-links. Not stack recommendations.

7Regulatory status by region

Region	Status (checked —)
United States	Not FDA-approved. Not specifically named on the 2023 Category 2 compounding list †; as an unapproved animal-derived drug it cannot be lawfully marketed for human use
European Union	Not authorised
United Kingdom	Not licensed
Australia	Not approved
South Africa	Not registered
Russia / CIS	Registered prescription medicine (Thymalinum) since 1982 for immunodeficiency states
Sport	Not specifically named by WADA; as a non-approved substance in most jurisdictions it falls under S0 †

8Open questions

What exactly is in a vial of thymalin, and does composition vary between manufacturers?
Would the elderly-mortality finding survive a properly randomised, blinded trial?
Are the synthetic dipeptides (Thymogen, Vilon) genuinely the active principle, or does the extract contain other contributors?

9References

1Khavinson VKh, Morozov VG (2003). Peptides of pineal gland and thymus prolong human life. Neuroendocrinol Lett. PubMed
2Khavinson VKh (2002). Peptides and ageing. Neuroendocrinol Lett (supplement). PubMed
3Morozov VG, Khavinson VKh (1997). Natural and synthetic thymic peptides as therapeutics for immune dysfunction. Int J Immunopharmacol. PubMed · DOI
4Anisimov VN, Khavinson VKh (2010). Peptide bioregulation of aging: results and prospects. Biogerontology. PubMed · DOI
5Khavinson VKh et al. (2020). Peptide regulation of gene expression: a systematic review. Molecules [verify exact title]. PubMed · DOI

† Being confirmed by our reviewers against current sources.

10Community

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11Page history

25 Oct 2026Profile published — awaiting medical review

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