Pinc PeptideThe girly peptide research blog

Thymalin · Dose evidence · updated 8 October 2026

Thymalin dosage: what studies actually used

The short answer

As of 7 October 2026, thymalin, an extract of calf thymus, is a prescription drug in Russia, and there is no US label dose because FDA has approved no thymalin product12. Vidal, a Russian drug reference, lists it as 10 mg vials for injection into muscle and gives adults with weakened immunity 5 to 20 mg a day for 3 to 10 days, with smaller doses for children from 6 months1. Two small COVID-19 trials in Russian hospitals gave 10 mg into muscle once a day, for 5 days in one and 10 days in the other34. The 2003 report behind anti-aging claims gives no doses in its abstract5, and we found no human study of injection under the skin. This page reports those doses and is not dosing advice.

Not dosing advice. This page reports doses that studies and approved labels used, with their sources. It does not recommend a dose, and we do not give mixing, injection or unit-conversion instructions. Gray-market vials often do not contain what their label says. How we report doses.

Every dose studied in people

StudyWhoPeopleDose and routeWhat happened
Khavinson 2021, open-label randomized trial at one hospital Adults in a Saint Petersburg hospital with moderate or severe COVID-19, April to July 2020; 42 given thymalin with standard care, 50 standard care alone 92 10 mg once a day
Injection into muscle · 5 days		 No one died in either group3. IL-6, an inflammation signal, fell from 20.35 to 3.69 pg/ml with thymalin and from 23.71 to 16.80 pg/ml with standard care alone, and lung scans worsened in 2 versus 5 patients3. The groups differed in other drugs, such as hydroxychloroquine (19% versus 10%), and the paper reports no count of side effects3.
Kuznik 2021, single-blind randomized trial with a salt-water placebo Adults with severe COVID-19 who needed oxygen, at Chita State Medical Academy Hospital; 36 given thymalin and 44 placebo, both with standard care 80 10 mg once a day
Injection into muscle · 10 days		 Clinical improvement 80.5% versus 59% and in-hospital deaths 19.4% versus 40.9% (p = 0.039 for both)4. Time to improvement (8.63 versus 7.61 days, p = 0.41) and lung scans on day 14 did not differ significantly, and the paper reports no count of side effects4.
Bushmelev 1994, controlled study as tagged by PubMed (in Russian) Children having surgery for widespread pus-forming peritonitis (infection of the abdominal lining); 21 treated, compared with a control group of unstated size – A 0.01% thymalin solution infiltrated into the wound edges; the amount is not given
Injection into wound edges · Not given in the abstract		 Complications were ‘much less’ common than in the control group, but thymalin was one part of a package with surgery, cleansing of the abdomen and other measures, so its own effect cannot be separated6.

Studies, animals and users: kept apart

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 days3 or 10 days4. The abstract of the 2003 aging report gives no doses5, 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 age8. 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 months9. 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’7.

Half-life and how it is taken

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)

What the Russian drug reference says

We could not open thymalin’s record in Russia’s official State Register of Medicines (GRLS) on 7 October 2026, so this section rests on Vidal, a Russian drug reference1. Vidal lists Thymalin as a prescription-only powder for injection into muscle, 10 mg of thymus extract per vial, under registration ЛП-№(005867)-(РГ-RU), dated 21 June 2024 with no expiry date1. Samson-Med of Saint Petersburg makes it, and its developers say Russia has approved it for medical use since 198231011.

Vidal’s text, last updated on 25 March 2025, lists thymalin for weakened immunity in adults and in children aged 6 months to 14 years who have1:

  • pus-forming or septic infections1;
  • lasting thymus problems, such as after radiation sickness, thymus tumors or removal of the thymus1;
  • acute or chronic viral and bacterial infections1;
  • poor healing and tissue repair1;
  • weakened immunity and blood-cell production after chemotherapy or radiotherapy for cancer1.

Vidal gives daily doses into muscle by age, for 3 to 10 days depending on how badly immunity is impaired; it presents them as a general description of the active substance and says the doctor decides the best regimen1.

It rules out thymalin in hypersensitivity, pregnancy and breastfeeding, urges caution in people with a history of allergies, and lists allergic reactions as the only side effect1. It also names the days around a period, pituitary adenoma (a noncancerous pituitary tumor) and acromegaly (excess growth hormone) as relative reasons not to use thymus-derived peptide drugs1.

Studies that did not report a dose

Five other human reports give no thymalin dose in their abstracts, the only part we could read512131415:

  • Khavinson and Morozov 2003: 266 older people followed for 6 to 8 years, given thymalin, epithalamin (a pineal gland extract) or both during the first 2 to 3 years; death rates were reported 2.0 to 2.1 times lower with thymalin than in a control group, but the abstract does not say how groups were formed or how many people were in each5.
  • Kuznik 2022: patients with severe COVID-19 in Chita given standard care alone, with tocilizumab or with thymalin; hospital deaths were 40.9%, 28.4% and 20.6%, and the abstract gives neither group sizes nor how patients were assigned12.
  • Kogosova 1990: 60 hospital patients with destructive lung tuberculosis; the authors report that thymalin, given by criteria based on immune tests alongside tuberculosis drugs, greatly shortened hospital stays, but the abstract gives no figures13.
  • Tkach 1992: 50 patients with ulcerative colitis; steroids worked better in active inflammation, and the authors preferred thymalin in mild inflammation14.
  • Kopchak 2004: 18 patients with acute necrotizing pancreatitis given immune drugs, thymalin in particular, with no control group described; the disease regressed in 12, 4 needed surgery and all survived15.

Thymulin, Thymogen and vials sold online

Thymalin is a mix of calf thymus peptides, not one molecule3. Thymulin, also called nonathymulin, is a single 9-amino-acid peptide, and Thymogen is a drug built on Glu-Trp, a dipeptide first isolated from thymalin and then made in the lab91617. They are different molecules, so their doses do not carry over to thymalin.

Online sellers offer ‘thymalin’ in vials labeled for research use, including a 25 mg vial whose listing gives the chemical formula of thymulin1618. As of 7 October 2026, Finnrick, an independent testing service, had published no thymalin tests, so what such vials contain is unknown19.

Questions people ask

How much thymalin should I take?

No dose is established for slowing aging or for immune support in healthy people, and the 2003 aging report gives no doses in its abstract5. In Russia, Vidal lists 5 to 20 mg a day into muscle for 3 to 10 days for adults with weakened immunity, with the regimen set by a doctor, and the COVID-19 trials used 10 mg a day134. Thymalin is not approved in the US, and by our reading US pharmacies may not compound it22021.

How long is a thymalin course?

Vidal gives daily injections for 3 to 10 days, depending on how badly immunity is impaired, with a repeat course after 1 to 6 months if needed1. The COVID-19 trials gave it for 5 days and for 10 days34. The 2003 aging report gave courses during the first 2 to 3 years, or every year for 6 years in one group, without stating doses in its abstract5.

What dose of thymalin was used for COVID-19?

Two Russian hospital trials published in 2021 gave 10 mg into muscle once a day, for 5 days in a 92-patient trial in Saint Petersburg and for 10 days in an 80-patient trial in Chita34. Both were small, and one of thymalin’s developers co-wrote both3410.

Can thymalin be injected subcutaneously?

The Russian product is a powder for injection into muscle, and both COVID-19 trials used that route134. We found no human study of thymalin injected under the skin.

Is thymalin given to children?

In Russia, Vidal lists it for weakened immunity in children aged 6 months to 14 years, with daily doses set by age group1. The only study in children we found injected a 0.01% solution into surgical wound edges as part of a package of measures, so it gives no usable dose6.

Go deeper

Sources

  1. 1Тималин (Thymalin), lyophilizate for intramuscular injection 10 mg: instructions for use Vidal Russia drug reference, 25 Mar 2025. vidal.ru
  2. 2Drugs@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
  3. 3Results 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
  4. 4Peptide Drug Thymalin Regulates Immune Status in Severe COVID-19 Older Patients Advances in Gerontology, 2021. link.springer.com
  5. 5Peptides of pineal gland and thymus prolong human life Neuroendocrinology Letters, 2003. pubmed.ncbi.nlm.nih.gov
  6. 6Prevention of postoperative complications in diffuse purulent peritonitis in children (in Russian) Khirurgiia, Aug 1994. pubmed.ncbi.nlm.nih.gov
  7. 7Thymalin: How It Works, Mechanism & Evidence (2026) The Peptide Catalog, 11 Jul 2026. thepeptidecatalog.com
  8. 8Effect 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
  9. 9Immunomodulatory synthetic dipeptide L-Glu-L-Trp slows down aging and inhibits spontaneous carcinogenesis in rats Biogerontology, 2000. pubmed.ncbi.nlm.nih.gov
  10. 10The Use of Thymalin for Immunocorrection and Molecular Aspects of Biological Activity Biology Bulletin Reviews, 2021. link.springer.com
  11. 11Тималин (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
  12. 12Morphological 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
  13. 13Effectiveness of administration of thymalin in the complex treatment of pulmonary tuberculosis (in Russian) Problemy tuberkuleza, 1990. pubmed.ncbi.nlm.nih.gov
  14. 14Differentiated immunocorrective therapy in nonspecific ulcerative colitis (in Russian) Likars’ka sprava, Apr 1992. pubmed.ncbi.nlm.nih.gov
  15. 15The application efficacy of immunomodulators in complex of treatment of an acute necrotic pancreatitis (in Ukrainian) Klinichna khirurhiia, Sep 2004. pubmed.ncbi.nlm.nih.gov
  16. 16Nonathymulin (PubChem CID 3085284) PubChem, National Center for Biotechnology Information, accessed 7 Oct 2026. pubchem.ncbi.nlm.nih.gov
  17. 17Natural and synthetic thymic peptides as therapeutics for immune dysfunction International Journal of Immunopharmacology, 1997. pubmed.ncbi.nlm.nih.gov
  18. 18Thymalin Peptide for Sale (25mg) Core Peptides (vendor), accessed 7 Oct 2026. corepeptides.com (seller page, deliberately not linked)
  19. 19Thymalin Safety Testing Results & Vendor Ratings Finnrick, accessed 7 Oct 2026. finnrick.com
  20. 20Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act U.S. Food and Drug Administration, 14 May 2026. fda.gov
  21. 21Bulk 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

Not medical advice. Talk to a licensed clinician before using any drug. Report an error.