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Immune · Evidence tier B

Thymalin

Тималин (Russian brand name) · Timalin, Thymalinum, Thymaline (other spellings) · Thymus extract (тимуса экстракт; the active substance named by Russian drug references)

Thymalin is a Russian prescription drug made from calf thymus glands: a mix of small peptides, not one molecule12. Its human trials are small and mostly run by its developers, and it is not approved in the US345.

Last reviewed · First published · 35 sources · 25 min read · By the Pinc Peptide editors

Illustration: a glass vial with a pink label reading Thymalin
Illustration, not a real product: an empty glass vial (photo: Missouri Historical Society, public domain) with our label. See every vial.

Quick answers

What is it?
An extract of thymus glands, an immune organ, from calves and young cattle under a year old1. It is a mix of small peptides, not one molecule26. Its developers say Russia has approved it as an immune drug since 19822.
Does it work?
Not proven. In two small trials in hospital COVID-19 patients, inflammation markers fell faster with it23. In one, of 80 patients, 19.4% died with it and 40.9% with a placebo3. Anti-aging claims rest on one developer report with unclear methods4.
Is it safe?
Not well studied. Vidal, a Russian drug reference, lists only allergic reactions as a side effect1. It rules out use in pregnancy and breastfeeding and urges caution with some hormone disorders1. Its developers say it has ‘practically no side effects’6.
Is it legal?
Not approved in the US, and by our reading US pharmacies may not make it578. Russia approves it as a prescription injection1. Sport’s banned list does not name it; by our reading, its Russian approval keeps it allowed1910.
What is in the vials?
Unknown. Finnrick, an independent testing service, had published no tests of it as of 7 October 202611. One seller’s 25 mg ‘Thymalin’ lists the chemical formula of thymulin, a different thymus peptide1213. The licensed Russian drug holds 10 mg of extract per vial1.

What it is

Thymalin is not a single molecule. Vidal, a Russian drug reference, describes each vial of the licensed drug as 10 mg of thymus extract, taken from the thymus glands of calves and young cattle up to one year old, with 20 mg of glycine1. Its developers call it ‘a complex of peptides isolated from the thymus of calves with a molecular weight of up to 10 kDa’2. They report that the short peptides EW (Glu-Trp), KE (Lys-Glu) and EDP (Glu-Asp-Pro) are among its parts6, and a 2023 paper from their institute calls the KE and EW dipeptides its ‘active substances’14. The thymus is an immune gland that shrinks with age3. According to Vidal, thymalin restores impaired immune responses by regulating the number and balance of T and B lymphocytes (two kinds of white blood cell), stimulates cell-based immunity and phagocytosis (immune cells engulfing germs), and stimulates tissue repair and blood-cell formation when these are suppressed1. The studies of how it works that we found come almost entirely from its developers’ institute614.

Thymalin was the first drug made with a method for extracting peptide complexes from the organs of young animals; V. G. Morozov and V. Kh. Khavinson described it in papers from 1981 and 1982615. Its developers say it has been approved for medical use in Russia since 19822. They later isolated the dipeptide Glu-Trp (EW) from thymalin and made it in the lab as a separate drug, Thymogen1617. Most later research comes from Khavinson’s Saint Petersburg Institute of Bioregulation and Gerontology and its collaborators214. Samson-Med of Saint Petersburg makes it218. Its current Russian registration, ЛП-№(005867)-(РГ-RU), dated 21 June 2024 with no expiry date, replaced the earlier ЛС-0002671, which a 2021 paper dates to 26 February 20103.

Benefits: what the research shows

The best human evidence is two small randomized trials in adults hospitalized with COVID-19 in Russia in 2020, both with Khavinson, one of thymalin’s developers, as an author. In an open-label trial in Saint Petersburg, 92 patients with moderate or severe disease were randomized by the envelope method to standard care with or without thymalin, 10 mg into muscle once a day for 5 days2. No one died in either group2. Lab markers fell further with thymalin: IL-6, an inflammation signal, fell 5.5-fold, against a fall from 23.71 to 16.80 pg/ml in controls; C-reactive protein fell 9.7-fold against 1.7-fold, and D-dimer, a clotting marker, 5.7-fold against 2.1-fold2. Lung scans worsened in 2 thymalin patients and 5 controls, and the groups differed in other drugs, such as hydroxychloroquine (19% vs 10%) and lopinavir-ritonavir (40.5% vs 56%)2. In a single-blind trial at Chita State Medical Academy, 80 patients with severe COVID-19, average age about 62, received thymalin 10 mg or salt-water injections into muscle daily for 10 days on top of standard care3. More thymalin patients improved (80.5% vs 59%) and fewer died in hospital (19.4% vs 40.9%; p = 0.039 for both), but time to improvement and day-14 lung scans did not differ significantly, and neither trial reported a count of side effects23. A 2022 report from the Chita group gives hospital deaths of 40.9% on standard care, 28.4% with tocilizumab and 20.6% with thymalin, without saying whether these are the same patients19. Claims that thymalin slows aging rest mainly on a 2003 report by Khavinson and Morozov on 266 older people followed for 6 to 8 years, who received thymalin, epithalamin (a pineal gland extract) or both during the first 2 to 3 years4. Compared with the control group, death rates were reported to be 2.0 to 2.1 times lower with thymalin, and acute respiratory illness 2.0 to 2.4 times less common4. The abstract does not say how people were put into groups, how many were in each or what doses they got, and we could not obtain the full text; PubMed nonetheless tags it as a randomized controlled trial4. The same report is often cited for epitalon, which it did not test. Older studies by other Soviet and Ukrainian clinicians are small and mostly uncontrolled or poorly described, in tuberculosis, ulcerative colitis, pancreatitis and peritonitis in children20212223. No thymalin study is registered on ClinicalTrials.gov24, and we found no human study from outside the former Soviet Union. Animal work comes mostly from the developers’ group: a thymus peptide extract lengthened life and cut tumors in mice treated from a young age, but not in mice treated from middle age25. A rat lifespan study that one seller credits to thymalin tested Thymogen, the lab-made dipeptide Glu-Trp, instead1217.

Key human studies

StudyDesignPeopleDose and routeResult
Kuznik et al., Advances in Gerontology 20213DOI Randomized, single-blind trial with a salt-water placebo at Chita State Medical Academy Hospital, Russia; adults with severe COVID-19 who needed oxygen; co-authored by Khavinson’s institute 80 10 mg into muscle once a day for 10 days, on top of standard care (control: salt-water injections) Clinical improvement 80.5% vs 59% and in-hospital deaths 19.4% vs 40.9% (p = 0.039 for both); time to improvement and day-14 lung scans did not differ significantly. More controls were on invasive ventilation during the study (45.4% vs 25%, p = 0.06). No count of side effects was reported3.
Khavinson et al., Stem Cell Rev Rep 20212PubMed · DOI Single-center, open-label randomized trial (envelope method) at St. Petersburg City General Hospital No. 2, April to July 2020; adults hospitalized with moderate or severe COVID-19 92 10 mg into muscle once a day for 5 days, on top of standard care No deaths in either group. IL-6 fell 5.5-fold with thymalin vs from 23.71 to 16.80 pg/ml with standard care alone; C-reactive protein 9.7-fold vs 1.7-fold; D-dimer 5.7-fold vs 2.1-fold. Lung scans worsened in 2 vs 5 patients. Use of hydroxychloroquine (19% vs 10%) and lopinavir-ritonavir (40.5% vs 56%) differed between groups2.
Khavinson and Morozov, Neuro Endocrinol Lett 20034PubMed Long-term study of older people with a control group, by thymalin’s developers with the Institute of Gerontology in Kiev; the abstract does not say how groups were formed, though PubMed tags it as randomized 266 Not given in the abstract; thymalin, epithalamin or both in the first 2 to 3 years of 6 to 8 years of follow-up Death rates reported 2.0 to 2.1 times lower with thymalin, 1.6 to 1.8 times lower with epithalamin and 2.5 times lower with both than in controls, and 4.1 times lower in a separate group given both every year for 6 years; acute respiratory illness 2.0 to 2.4 times less common4.
Kuznik et al., Adv Gerontol 202219PubMed Three-group comparison in middle-aged and older patients with severe COVID-19, Chita, Russia (in Russian); the abstract gives neither how patients were assigned nor group sizes – Not given in the abstract; standard care alone, plus tocilizumab, or plus thymalin Hospital deaths 40.9% with standard care, 28.4% with tocilizumab and 20.6% with thymalin. Thymalin doubled lymphocyte and monocyte counts and lowered fibrinogen, LDH (a tissue-damage marker) and D-dimer 1.2-, 1.8- and 1.7-fold19.
Tkach et al., Lik Sprava 199221PubMed Comparison of steroid hormones and thymus drugs in patients with ulcerative colitis (in Russian); the abstract does not say how patients were assigned 50 Not given in the abstract Steroids worked better in active inflammation of the bowel lining; the authors preferred thymalin in mild inflammation. The abstract gives no figures21.
Bushmelev et al., Khirurgiia (Mosk) 199423PubMed Controlled clinical study (as tagged by PubMed) in children with diffuse purulent peritonitis, 21 of them treated; thymalin was one part of a package of measures (in Russian); control group size not given – Wound edges infiltrated with 0.01% thymalin solution, alongside surgery, cleansing of the abdomen and other measures Complications were ‘much less’ common than in the control group; the abstract gives no figures, and thymalin’s own effect cannot be separated from the other measures23.

Doses studied

Doses below are what studies used or what a label says. They are not advice, and gray-market products may not contain what their label says.

In human studies

Vidal, a Russian drug reference, which says the doctor sets the regimen: into muscle once a day, 5 to 20 mg for adults (30 to 100 mg per course) and 1 to 5 mg for children aged 6 months to 14 years, depending on age, for 3 to 10 days; a course may be repeated after 1 to 6 months, and preventive courses are 5 to 10 mg a day for adults (1 to 5 mg for children) for 3 to 5 days1. It has no dosing data for people with kidney or liver problems or for older people1. COVID-19 trials: 10 mg into muscle once a day for 5 days2 or 10 days3. The abstract of the 2003 aging report gives no doses4, and we found no human study of injections under the skin.

In animal studies

As reported. Mice: 0.1 mg of a thymus peptide extract per injection under the skin, in 5-day courses every month, starting at 3.5 or 12 months of age25. Rats: 5 µg per rat of the dipeptide Glu-Trp (Thymogen, one component of thymalin made in the lab, not thymalin itself) under the skin 5 times a week for 12 months17. These are animal doses, not human doses.

What users report Anecdotal · not validated · not a recommendation

One community reference site lists 5 to 10 mg a day, given into muscle or under the skin, and says these are ‘figures reported in Russian clinical literature, not a validated Western dose’32.

Routes
  • Injection into a muscle (the licensed Russian route; used in both COVID-19 trials)
  • Injection into wound edges (one small Russian surgical study in children)
  • Injection under the skin (described by a community site; used in mouse studies of a thymus peptide extract; no human data found)

Every dose studied for Thymalin, with sources →

Quality and the gray market

What testing finds

We found no independent test results. Finnrick, an independent testing service, listed no vendors and no tests for thymalin on 7 October 202611. Sellers describe the product in conflicting ways. One lists a 25 mg vial, ‘99%+ by HPLC’, with the formula C33H54N12O15 and the other names ‘Thymulin, Thymic Factor’12; that is the formula of nonathymulin (thymulin), a single 9-amino-acid thymus peptide13. Another calls its 10 mg vials a ‘peptide complex’ with no single formula, ‘Produced in the USA’33. A purity figure, which usually measures one main compound, is hard to apply to a product its developers describe as a complex of peptides2. The licensed Russian product contains 10 mg of thymus extract and 20 mg of glycine per vial and is made by Samson-Med in Russia118. openFDA’s recall database has no entry naming thymalin28.

How it is sold

Thymalin is sold online as freeze-dried powder in vials labeled for research use. On 7 October 2026 one online vendor listed a 25 mg vial at $138, with lower prices for larger orders, saying its peptides are ‘sold for laboratory research use only’ and ‘not for human consumption’12. That page credited ‘Thymalin’ with a rat lifespan study that actually tested Glu-Trp, the lab-made dipeptide developed as the drug Thymogen1217. Another vendor listed 10 mg vials at $51, down from $60, ‘for research use only’, under ‘Metabolic Regulation & Energy Pathway Research’33. RLS lists a reference price of 1,101 rubles for a pack of ten 10 mg vials of the licensed drug18. Demand looks very small: Finnrick had no thymalin tests by 7 October 202611, and the r/thymalin subreddit showed 1 weekly visitor and no weekly contributions that day34. A community reference site that covers thymalin describes it as distinct from thymulin and thymosin alpha-132.

Side effects and risks

  • Little safety data: Vidal, a Russian drug reference, lists only allergic reactions as a side effect1, neither COVID-19 trial reported a count of side effects, and we found no long-term safety study23. Its developers say it has ‘practically no side effects’6.
  • Allergy and animal origin: Vidal warns of allergic reactions and urges caution in people with a history of allergy1. The licensed drug is made from the thymus glands of calves and young cattle1; online sellers do not say what animal their products come from1233.
  • Hormone cautions: Vidal rules out use in pregnancy and breastfeeding, and lists the days around a period, pituitary adenoma (a noncancerous pituitary tumor) and acromegaly (excess growth hormone) as relative reasons not to use it1. It says side effects are more common in severe hormone disorders and in the second half of the menstrual cycle, and that thymalin may add to the effects of growth hormone, LH and estrogens and work against progestins, androgens and adrenal hormones1.
  • Unknown contents: no independent lab has published tests of gray-market thymalin, and sellers describe it in conflicting ways, one giving the formula of thymulin, a different peptide111233.
  • Legal and sport risk: US pharmacies may not make it7, Health Canada says ‘For Research Use Only’ labels do not make peptide products legal30, and WADA’s note on its 2027 List urges ‘utmost caution’ with peptides it does not name31.

Documented harms

  • 30 Jul 2026As of openFDA’s 30 July 2026 update, FDA’s adverse event database (FAERS) holds 3 reports naming thymalin, each listing it as a drug taken alongside the suspected ones rather than as a suspect. One, received 27 March 2015 from the US, describes a 58-year-old woman on chemotherapy for breast cancer who was hospitalized with raised liver enzymes and was also taking ‘Thymaline’ for a low white-cell count. The other two, received 24 September 2012 and 26 September 2012 from Ukraine, appear to describe the same 51-year-old man on chemotherapy for stomach cancer who was hospitalized with stomach bleeding and was also taking ‘Thymalinum’ for weakness. Reports are unverified and do not show that thymalin caused harm27.

Questions people ask

Is thymalin the same as thymulin?

No. Thymalin is a mix of peptides extracted from calf thymus2, while thymulin, also called nonathymulin, is a single 9-amino-acid peptide13. A review of thymus preparations lists them separately35, but PubChem files ‘Thymalin’ as a synonym of nonathymulin, and one seller gives thymulin’s formula for its thymalin1213.

Is thymalin FDA approved?

No. Drugs@FDA lists no product containing it, and US pharmacies may not compound it57. It is a prescription drug in Russia1.

What is thymalin used for?

In Russia it is prescribed for weakened immunity, for example in pus-forming or long-lasting infections, after radiation or removal of the thymus, after chemotherapy, or when healing is impaired1. Online it is promoted for immune support and aging1232.

Does thymalin slow aging?

Not shown. The main human evidence is a 2003 report by its developers on 266 older people, with death rates 2.0 to 2.1 times lower on thymalin than in a control group4. The abstract does not explain how groups were formed or what doses were used, and we found no independent study that repeated it.

Does thymalin work for COVID-19?

Possibly, but the evidence is small. In two Russian trials from 2020, both co-authored by one of its developers, inflammation markers fell faster, and in the single-blind one, of 80 patients, 19.4% died with thymalin vs 40.9% with placebo23. No larger or independent trial is registered24.

What are the side effects of thymalin?

Vidal, a Russian drug reference, lists only allergic reactions1. It rules out use in pregnancy and breastfeeding and says side effects are more common in people with severe hormone disorders1. Neither COVID-19 trial reported a count of side effects, so the true rate is unknown23.

Are there clinical trials of thymalin?

Only a few small ones. Khavinson, one of its developers, is an author of both COVID-19 trials and the 2003 aging report234. Other clinicians in the former Soviet Union published small studies, mostly before 2005; none is registered on ClinicalTrials.gov, and we found none from elsewhere20222324.

Is thymalin banned in sport?

It is not named on WADA’s 2026 or 2027 Prohibited List910. By our reading, its Russian approval keeps it outside the catch-all ban on unapproved substances, but this is not a WADA ruling, and WADA urges ‘utmost caution’ with peptides it does not name131.

What is still unknown

  • How the 2003 aging study formed its groups, how many people were in each and what doses they received; only the abstract could be read, though PubMed tags it as a randomized controlled trial.
  • Whether the 2022 Chita report re-uses patients from the 2021 Chita trial: the control death rate (40.9%) is the same, but thymalin’s differs (20.6% vs 19.4%).
  • What side effects the COVID-19 trials saw; neither reported a count.
  • Whether the Russian registration is current in the official State Register of Medicines (GRLS), which could not be opened; Vidal lists it as valid with no expiry date.
  • Whether thymalin is approved in other former Soviet countries, and its status in the UK and EU.
  • How long thymalin’s peptides last in the body; no study of this was found.
  • What gray-market ‘thymalin’ vials contain; no independent test has been published.
  • Whether the thymus peptide extract in the developers’ 1989 mouse study was thymalin; the abstract does not name it.

Sources

  1. 1Тималин (Thymalin), lyophilizate for intramuscular injection 10 mg: instructions for use Vidal Russia drug reference, 25 Mar 2025. vidal.ru
  2. 2Results and Prospects of Using Activator of Hematopoietic Stem Cell Differentiation in Complex Therapy for Patients with COVID-19 Stem Cell Reviews and Reports, Feb 2021. pubmed.ncbi.nlm.nih.gov
  3. 3Peptide Drug Thymalin Regulates Immune Status in Severe COVID-19 Older Patients Advances in Gerontology, 2021. link.springer.com
  4. 4Peptides of pineal gland and thymus prolong human life Neuroendocrinology Letters, 2003. pubmed.ncbi.nlm.nih.gov
  5. 5Drugs@FDA via openFDA: search for active ingredient thymalin (no matches) U.S. Food and Drug Administration (openFDA), accessed 7 Oct 2026. api.fda.gov · data query
  6. 6The Use of Thymalin for Immunocorrection and Molecular Aspects of Biological Activity Biology Bulletin Reviews, 2021. link.springer.com
  7. 7Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act U.S. Food and Drug Administration, 14 May 2026. fda.gov
  8. 8Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act (categories list) U.S. Food and Drug Administration, 14 May 2026. fda.gov
  9. 9World Anti-Doping Code International Standard: Prohibited List 2026 World Anti-Doping Agency, 24 Sep 2025. wada-ama.org
  10. 10World Anti-Doping Code International Standard: Prohibited List 2027 World Anti-Doping Agency, 21 Sep 2026. wada-ama.org
  11. 11Thymalin Safety Testing Results & Vendor Ratings Finnrick, accessed 7 Oct 2026. finnrick.com
  12. 12Thymalin Peptide for Sale (25mg) Core Peptides (vendor), accessed 7 Oct 2026. corepeptides.com (seller page, deliberately not linked)
  13. 13Nonathymulin (PubChem CID 3085284) PubChem, National Center for Biotechnology Information, accessed 7 Oct 2026. pubchem.ncbi.nlm.nih.gov
  14. 14The 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 International Journal of Molecular Sciences, 29 Aug 2023. pubmed.ncbi.nlm.nih.gov
  15. 15Experimental and clinical study of a new immunoregulator preparation thymalin (in Russian) Voenno-meditsinskii zhurnal, May 1982. pubmed.ncbi.nlm.nih.gov
  16. 16Natural and synthetic thymic peptides as therapeutics for immune dysfunction International Journal of Immunopharmacology, 1997. pubmed.ncbi.nlm.nih.gov
  17. 17Immunomodulatory synthetic dipeptide L-Glu-L-Trp slows down aging and inhibits spontaneous carcinogenesis in rats Biogerontology, 2000. pubmed.ncbi.nlm.nih.gov
  18. 18Тималин (Thymalin), lyophilizate for intramuscular injection 10 mg: active substance, ATC code, analogs and price RLS (Register of Medicinal Products of Russia), 22 Sep 2026. rlsnet.ru
  19. 19Morphological compound and indicators of the blood clotting system in severe COVID-19 patients of middle aged and elderly during treatment of Tocilizumab and Thymalin (in Russian) Uspekhi Gerontologii (Advances in Gerontology), 2022. pubmed.ncbi.nlm.nih.gov
  20. 20Effectiveness of administration of thymalin in the complex treatment of pulmonary tuberculosis (in Russian) Problemy tuberkuleza, 1990. pubmed.ncbi.nlm.nih.gov
  21. 21Differentiated immunocorrective therapy in nonspecific ulcerative colitis (in Russian) Likars’ka sprava, Apr 1992. pubmed.ncbi.nlm.nih.gov
  22. 22The application efficacy of immunomodulators in complex of treatment of an acute necrotic pancreatitis (in Ukrainian) Klinichna khirurhiia, Sep 2004. pubmed.ncbi.nlm.nih.gov
  23. 23Prevention of postoperative complications in diffuse purulent peritonitis in children (in Russian) Khirurgiia, Aug 1994. pubmed.ncbi.nlm.nih.gov
  24. 24ClinicalTrials.gov search for ‘thymalin’ or ‘timalin’ (no registered studies) ClinicalTrials.gov, accessed 7 Oct 2026. clinicaltrials.gov
  25. 25Effect of low-molecular-weight factors of thymus and pineal gland on life span and spontaneous tumour development in female mice of different age Mechanisms of Ageing and Development, Sep 1989. pubmed.ncbi.nlm.nih.gov
  26. 26Therapeutic Goods (Poisons Standard—October 2026) Instrument 2026 (F2026L01327) Federal Register of Legislation, Australian Government, 28 Sep 2026. legislation.gov.au
  27. 27FDA Adverse Event Reporting System (FAERS) reports naming thymalin, retrieved via the openFDA drug/event API (3 reports) U.S. Food and Drug Administration (openFDA), 30 Jul 2026. api.fda.gov · data query
  28. 28Drug recall (enforcement) records via openFDA: search for thymalin (no matches) U.S. Food and Drug Administration (openFDA), accessed 7 Oct 2026. api.fda.gov · data query
  29. 29Bulk Drug Substances Nominated for Use in Compounding Under Section 503B of the Federal Food, Drug, and Cosmetic Act (categories list) U.S. Food and Drug Administration, 21 Mar 2025. fda.gov
  30. 30Think twice before injecting peptides bought online: unauthorized products can seriously harm you (RA-81874) Health Canada, 9 Apr 2026. recalls-rappels.canada.ca
  31. 31Summary of Major Modifications and Explanatory Notes: 2027 Prohibited List World Anti-Doping Agency, 21 Sep 2026. wada-ama.org
  32. 32Thymalin: How It Works, Mechanism & Evidence (2026) The Peptide Catalog, 11 Jul 2026. thepeptidecatalog.com
  33. 33Thymalin 10 mg Peptide Complex | Research Grade | AminoVault AminoVault (vendor), accessed 7 Oct 2026. aminovault.com (seller page, deliberately not linked)
  34. 34r/thymalin (official subreddit embed page; weekly visitors) Reddit, accessed 7 Oct 2026. embed.reddit.com
  35. 35Contemporary Views on the Nature and Clinical Application of Thymus Preparations Russian Journal of Immunology, Dec 1997. pubmed.ncbi.nlm.nih.gov

Not medical advice. This page reports what studies and regulators say; it does not recommend using any product. How we grade evidence · Report an error.