Evidence: LowBlend or mixtureNot FDA ApprovedCalf-thymus polypeptide mixtureApproved in RussiaImmune modulation

Thymalin

A polypeptide preparation extracted from calf thymus, prescribed in Russia as an immune modulator and studied almost entirely there

Thymalin is not a single peptide but a mixture of polypeptides from calf thymus, sold in Russia as an injected immune modulator. Its studies are small, mostly Russian, and usually add it to other treatment, so what the mixture does alone is hard to read.

At a Glance Read Research →

Overview

What is it?

Thymalin is an extract, so no formula, molecular weight or measured half-life describes it. In cell work it shifted human blood stem cells towards mature T cells: markers of the stem and intermediate stages fell two- to threefold while the mature T-cell marker CD28 rose nearly sevenfold.

Its human studies are small and old, and in most of them thymalin is added to something else. Fifteen people with Parkinson's disease were assessed before and after a course, with no control group; 36 people with treatment-resistant schizophrenia took it alongside their psychiatric drugs. The most recent is a comparison in severe COVID-19 in which hospital mortality was 40.9% on standard care, 28.4% with tocilizumab and 20.6% with thymalin, with blood counts and clotting markers also differing; the groups were not randomised.

Animal work is suggestive rather than decisive: thymalin below the usual dose stopped or shrank transplanted sarcoma in more than half of treated rats, and injected around a jaw defect it sped bone repair. None of this has been reproduced outside the region, and thymalin is not approved in the US, the EU, the UK or Canada.

20.6%

Hospital mortality with thymalin

severe COVID-19, vs 40.9% on standard care

6.8×

Rise in the mature T-cell marker CD28

human stem cells in culture

Patients in the largest trial here

resistant schizophrenia, as an add-on

Structured data

At a Glance

Every value in this table is printed from the Grey Peptides dataset, the same record the compound explorer and comparison tool read, so the three can never disagree.

ClassA polypeptide complex extracted from calf thymus, historically marketed in Russia as an immune-supportive therapy and positioned in the Khavinson framework as a thymic-aging bioregulator.

SequencePolypeptide mixture — not a single-sequence molecule

Half-lifeNot established

Typical doseintramuscular

US statusNot FDA Approved

Approved elsewhereRussia

Evidence levelLow

Last reviewed2026-09-30

Evidence

Published Research

These are the studies that describe thymalin, read from their PubMed abstracts: three in people, one in human cells and two in rats.

Human2022

Severe COVID-19: thymalin against tocilizumab

Middle-aged and elderly patients with severe COVID-19 received standard care, tocilizumab or thymalin. Hospital mortality was 40.9%, 28.4% and 20.6% respectively. Thymalin doubled lymphocyte and monocyte counts and lowered fibrinogen, lactate dehydrogenase and D-dimer. Patients were not randomised.

PMID: 36169363

Human2020

Human blood stem cells in culture

Thymalin cut the stem-cell marker CD44 and the intermediate marker CD117 two- to threefold and raised CD28, a marker of mature T cells, 6.8-fold, which the authors read as stem cells being pushed towards mature T lymphocytes.

PMID: 33237528

Human1999

Parkinson's disease: 15 patients

Fifteen people aged 45 to 72 with early idiopathic parkinsonism were assessed before and after a course of thymalin. The authors report improvement in tremor, rigidity and slowness and changes on EEG mapping. There was no control group.

PMID: 10424021

Human1990

Treatment-resistant schizophrenia: 36 patients

Thymalin was added to psychiatric drugs in 36 patients with immune abnormalities. The authors report better response and fewer drug complications, correlating with normalised immune measures, most in patients whose resistance was drug-related.

PMID: 2163147

Animal2018

Transplanted sarcoma in rats

At doses below the usual therapeutic range, thymalin stopped or reversed tumour growth in more than half of rats with transplanted sarcoma 45 and suppressed it by 78% in the rest, alongside changes in the thymus.

PMID: 29797130

Animal2024

Jaw bone repair in rats

In 48 rats with a drilled mandible defect, injecting thymalin into the surrounding soft tissue, with or without a hydroxyapatite graft, sped the clearing of the defect and the mineralisation of new bone.

PMID: 38431810

Safety

Side Effects & Contraindications

Reported Side Effects

The published studies report little on side effects; these are the limits that matter more.

● Thymalin is an animal-tissue extract, not a defined molecule

● Most human studies add it to other treatment, so its own effect is hard to separate

● The COVID-19 comparison was not randomised

Contraindications & Cautions

Thymalin has no US label. These cautions follow from what it is and how little has been tested.

● Any use outside Russia's approved indications — no other regulator has reviewed it

● Products sold for research use — identity, purity and sterility are unverified

● Tested athletes — see the Sport (WADA) row below

Regulatory

Legal Status

Thymalin is approved in Russia and nowhere else.

JurisdictionStatusNotes

United StatesNot approvedDrugs@FDA holds no application for thymalin (openFDA, read September 30, 2026).

Sport (WADA)Unsettled (S0 may apply)Not named on the 2026 List. S0 only reaches substances with no current approval by any governmental regulatory health authority, and this one is approved outside the US (Russia). If that approval is current, S0 does not apply; we have not verified it at the foreign regulator, so we do not read this row either way: ask Global DRO or your anti-doping organisation. Still not named in the 2027 List (published September 21, 2026; in force January 1, 2027); S0's text now lists “peptides” among its examples of non-approved substances. Source: the 2026 and 2027 WADA Prohibited Lists, read on September 27, 2026.

Questions

Frequently Asked Questions

?What is thymalin?

A mixture of polypeptides extracted from calf thymus, injected as an immune modulator and approved in Russia.

?Is there good evidence for it?

Not by trial standards: its human studies are small, mostly add it to other treatment, and the COVID-19 comparison was not randomised.

?Is thymalin approved in the US?

No. Drugs@FDA holds no application for it, as of September 30, 2026.

?Does it have a known half-life?

No. It is an extract, not a single molecule, so none has been measured.

Bibliography

References

[fda] FDA. Drugs@FDA (openFDA): no application for thymalin. Read September 30, 2026.
[pubmed] Kuznik BI, et al. "[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.]." Adv Gerontol, 2022;35(3):368-374. PMID: 36169363.
[pubmed] Khavinson VK, et al. "Thymalin: Activation of Differentiation of Human Hematopoietic Stem Cells." Bull Exp Biol Med, 2020;170(1):118-122. PMID: 33237528.
[pubmed] Musienko GV. "[Thymalin in the combined treatment of parkinsonism patients]." Lik Sprava, 1999:119-22. PMID: 10424021.
[pubmed] Govorin NV, et al. "[Use of thymic peptide thymalin in the complex treatment of therapy-resistant schizophrenia]." Zh Nevropatol Psikhiatr Im S S Korsakova, 1990;90(3):100-3. PMID: 2163147.
[pubmed] Zhukova GV, et al. "Effect of Thymalin on the Tumor and Thymus under Conditions of Activation Therapy In Vivo." Bull Exp Biol Med, 2018;165(1):80-83. PMID: 29797130.
[pubmed] Boiko AA, et al. "Reparative osteogenesis in mandible in cases of filling a bone defect with hydroxyapatite-containing osteotropic material and injecting the surrounding soft tissues with thymalin: experimental and morphological study." Wiad Lek, 2024;77(1):68-76. PMID: 38431810.
[other] Тималин® (Thymalin) instructions for medical use, Samson-Med, Russia: thymus extract 10 mg for intramuscular injection; prescription-only per RLS. Read September 30, 2026.

Sources & Citations

Studies were read from PubMed; regulatory sources are listed below, read September 30, 2026.

Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Consult a licensed healthcare provider before making health decisions.

Last reviewed: 2026-09-30