Thymalin dosage and evidence

What is Thymalin?

How does Thymalin work?

Thymalin gives the body a mix of thymus signalling peptides. The idea is to make up for the thymus shrinking with age. In human blood stem cells in a dish, it lowered two stem cell markers (CD44 and CD117) 2 to 3 times. It raised CD28, a marker of mature T cells, 6.8 times. The authors read this as a push toward mature T cells. Two tiny peptides are thought to be its active parts. Lys-Glu is reported to switch on several kinds of immune cells. Glu-Trp was pulled out of Thymalin in the 1990s and later made on its own as the drug Thymogen. Because Thymalin is an extract, not one defined molecule, each batch can differ. No single weight or strength unit describes it.

What have studies in people found about Thymalin?

Thymalin has more human use behind it than almost any compound on this site that no Western regulator has ever reviewed. It has been used in normal hospital care in the Soviet Union and Russia since the 1980s. PubMed lists 195 records for it in people. Almost all are short Russian reports. The two with usable numbers both come from the group that made it.

• 266 older people in Russia and Ukraine were followed for 6 to 8 years. They were treated in the first 2 to 3 years. In the Thymalin group, colds and chest infections fell 2.0 to 2.4 times, and deaths were 2.0 to 2.1 times lower than in the untreated group. With Epithalamin added, deaths were reported 2.5 times lower. In a smaller group that took both every year for 6 years, they were 4.1 times lower. Khavinson and Morozov, Neuro Endocrinology Letters, 2003.
• COVID, the clearest study on this compound. It ran at one hospital from April to July 2020, and everyone knew who got what. 42 patients got thymalin 10 mg as a shot into the muscle every day for 5 days, plus normal care. 50 got normal care alone. Nobody died in either group. Lung scans got worse in 2 of 42 treated patients and 5 of 50 others. Blood markers of inflammation and clotting (IL-6, C-reactive protein and D-dimer) fell faster on thymalin. Khavinson and colleagues, Stem Cell Reviews and Reports, 2021.
• Another study in severe COVID reported hospital deaths of 40.9% on normal care, 28.4% with tocilizumab and 20.6% with thymalin. It does not give group sizes. The paper's own Russian summary gives different numbers for two of the three groups than its English summary does. Kuznik and colleagues, Advances in Gerontology, 2022.
• Behind these sits a long list of small Russian studies from the 1980s on. They cover tuberculosis, burns, infections after surgery, pancreatitis, ulcerative colitis, chronic bronchitis and inflammation of women's reproductive organs. One is a 2015 study from Novosibirsk. It timed thymalin doses to each patient's own immune cell activity in long-running inflammation of the tubes and ovaries. These reports are short. Patients almost always knew what they got. Thymalin was usually one part of a mix of treatments. Most cannot be read in English beyond the summary.
• This one is human cells in a dish, not people. In human blood stem cells, thymalin cut two stem cell markers (CD44 and CD117) 2 to 3 times. It raised CD28, a marker of mature T cells, 6.8 times. Khavinson and colleagues, Bulletin of Experimental Biology and Medicine, 2020.
• No study of thymalin is registered on ClinicalTrials.gov as of September 2026. Thymalin was not one of the seven peptides the FDA advisory panel reviewed on July 23 to 24, 2026.

What this does not tell you: That thymalin lowers deaths or infections. The COVID study is the only one here with a clear design, clear group sizes and a comparison group. But everyone knew who got what, it ran at one hospital, and nobody died in either group. So it cannot tell us anything about deaths. The 266-person study gave ratios, not actual counts of deaths or how sure the numbers are. Its Thymalin and Epithalamin groups also overlapped. Under all of it is the mix problem. Thymalin is a thymus extract, not one defined molecule. A result from one batch may not carry over to another, and a dose in milligrams has no fixed meaning. There is no study with a hidden dummy treatment, no registered plan, no outside group repeating any result, and no long-term safety data outside the Russian record.

What do people who took Thymalin report?

This is what real people say happened to them, good and bad. Nobody measured it. A report cannot tell a real effect from the lift people get just from expecting it to work, from a diet or training change made at the same time, or from what was really in the vial. We still put it near the top. It is the next best thing to a study in people: what happens when real people use it, including what goes wrong.

• Thymalin is a niche product in Western peptide circles. People talk about it far less than Thymosin Alpha-1. Most find it while reading about Khavinson's peptides, not while looking for an immune peptide.
• The plan people copy is a short course, not steady use. It is roughly 5 to 10 mg a day for 5 to 10 days in a row, repeated after about six months. That comes from the Russian studies, where the shots went into the muscle.
• Online use differs from the studies in one way people rarely mention. The Russian studies used shots into the muscle. Most online plans use shots under the skin. No study supports that switch, and the guides that suggest it say so.
• Reported effects are vague and slow, and people usually admit that. They talk about fewer infections and faster recovery over a season, not anything felt during the course. That makes it close to impossible for one person to judge against how they were before.
• Sourcing is the biggest practical complaint. Thymalin is a tissue extract, not a lab-made peptide, so a buyer cannot check it against a known sequence. A lab report showing purity means nothing for a mix. Outside Russia, there is no practical way to know a vial holds what the Russian studies used.
• Mixing up products is common. Some seller and guide pages call Thymalin the dipeptide Glu-Trp. It is not. Glu-Trp was pulled out of Thymalin and made separately as Thymogen. Others treat Thymalin and Thymosin Alpha-1 as the same thing. Anyone comparing dose advice across sources is probably reading about three different products.

Sources: Peptide community protocol and dosing guides (thepeptidecatalog.com, pathtopeptides.com, peptidewiki.co), which state that their protocols are research-chemical community practice without controlled-trial support; general Khavinson bioregulator discussion in longevity forums. Reddit's r/Peptides and r/Biohackers are the most cited venues for this compound but were not directly readable when this section was compiled, so nothing here is drawn from them.

The state of the research

The evidence, in charts

The studies we cite

• Study in people2003
  Peptides of pineal gland and thymus prolong human life

  This is the study the thymalin story rests on, and it is not built to carry it. 266 older people in Russia and Ukraine were followed for six to eight years, dosed only in the first two or three. In the thymalin group, chest and airway infections were reported at roughly half the usual rate, and deaths at about half as well. Adding the pineal peptide was reported to lower deaths further still. Everybody knew who got what, and every figure comes from one research group.

  266 elderly people in Russia and Ukraine followed 6 to 8 years, treated during the first 2 to 3 years: in the Thymalin arm acute respiratory illness fell 2.0 to 2.4-fold and mortality was 2.0 to 2.1-fold lower than control; combined with Epithalamin the reported reduction was 2.5-fold, and 4.1-fold in a subgroup dosed annually for 6 years. Open-label, single research lineage.

  PMID 14523363 Neuro Endocrinology Letters
• Study in people2021
  Results and prospects of using activator of hematopoietic stem cell differentiation in complex therapy for patients with COVID-19

  A small early-pandemic trial reported faster recovery, and nobody died in either group. 42 patients got thymalin injections into the muscle for five days on top of standard care, and 50 got standard care alone, at one hospital in mid 2020. Lung scans worsened in 2 of the 42 treated against 5 of the 50 controls. Markers of inflammation fell faster on the drug. Everybody knew who was getting it. With no deaths at all, the trial cannot say whether thymalin saves lives.

  Single-centre, open-label, prospective randomized controlled trial, April to July 2020: 42 patients received thymalin 10 mg intramuscularly daily for 5 days plus standard care, 50 received standard care. No deaths in either group. Radiological progression in 2 of 42 treated against 5 of 50 controls, with faster falls in IL-6, C-reactive protein and D-dimer.

  PMID 33575961 Stem Cell Reviews and Reports
• Study in people2022
  Morphological composition and blood clotting indicators in severe COVID-19 patients treated with tocilizumab or thymalin

  The reported death rates favour thymalin, and the paper contradicts itself. Severely ill COVID patients were split three ways: standard care, tocilizumab, or thymalin. The English abstract puts hospital deaths at 40.9% on standard care, 28.4% with tocilizumab and 20.6% with thymalin. The Russian abstract of the same paper gives different figures for two of those groups. Group sizes are never reported anywhere. A death rate with no group size behind it, in a paper that disagrees with itself, cannot be relied on.

  Three-arm comparison in severe COVID-19 in middle-aged and elderly patients: hospital mortality 40.9% on standard therapy, 28.4% with tocilizumab and 20.6% with thymalin, per the English abstract. Group sizes are not reported, and the paper's own Russian abstract gives different figures for two arms (28.8% and 16.2%).

  PMID 36169363 Advances in Gerontology
• Study in people2015
  Chrono- and immunocorrection of inflammatory disorders of internal reproductive organs in women of reproductive age

  A small Russian trial about timing the dose, not about whether the drug works. Women of reproductive age with long-running inflammation of the tubes and ovaries were given thymalin, timed to their own immune cells' activity. Improvement in symptoms, blood tests and immune measures was more common when the drug was given while that activity was present. The study was small, nobody was kept in the dark, and it was never designed to separate thymalin from the rest of the treatment.

  Novosibirsk clinical trial in chronic salpingitis and oophoritis timing thymalin to each patient's own lymphocyte succinate dehydrogenase response. Clinical, laboratory and immunological improvement was more frequent when the drug was given while that response was present. An example of the broader Russian clinical literature; small, unblinded, and not designed to isolate thymalin's effect.

  PMID 26033592 Bulletin of Experimental Biology and Medicine
• Review of studies1997
  Natural and synthetic thymic peptides as therapeutics for immune dysfunction

  The makers' own account of what Thymalin is. It is natural peptides pulled from calf thymus with a mild acid, then used to correct the immune system. The dipeptide Glu-Trp was later pulled out of it and made separately as Thymogen.

  The originators' own account of what Thymalin is: natural peptides extracted from calf thymus by mild acid extraction and put into practice as an immunocorrector, from which the dipeptide Glu-Trp was isolated by reversed-phase HPLC and developed separately as Thymogen.

  PMID 9637345 International Journal of Immunopharmacology
• Review of studies2026
  July 23-24, 2026: Meeting of the Pharmacy Compounding Advisory Committee

  The official FDA meeting agenda. The panel looked at BPC-157, KPV, TB-500, MOTS-c, Emideltide, Epitalon and Semax. Thymalin was not on the list, so nothing about its US status changed in July 2026.

  The official agenda lists the substances considered: BPC-157, KPV, TB-500, MOTS-c, Emideltide, Epitalon and Semax. Thymalin was not among them, so nothing about its US status changed in July 2026.

  Source U.S. Food and Drug Administration
• Lab (cells in a dish)2020
  Thymalin: activation of differentiation of human hematopoietic stem cells

  In a dish. In human blood stem cells, thymalin cut two stem cell markers 2 to 3 times and raised a mature T cell marker 6.8 times. The authors read this as a push toward mature T cells.

  In cultured human hematopoietic stem cells, Thymalin reduced CD44 and CD117 expression 2 to 3-fold and raised the mature T-cell marker CD28 6.8-fold, which the authors read as differentiation toward mature T lymphocytes.

  PMID 33237528 Bulletin of Experimental Biology and Medicine
• Lab (cells in a dish)2023
  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

  In a dish and on a computer. The authors modelled how two tiny peptides in Thymalin, Lys-Glu and Glu-Trp, might act on genes. They tested them on human blood immune cells. They propose these two are the active parts behind Thymalin's immune effects.

  Molecular docking, promoter and pathway analysis plus an LPS-stimulated human peripheral blood mononuclear cell model, proposing Lys-Glu and Glu-Trp as the active components behind Thymalin's reported immunomodulatory effect.

  PMID 37686182 International Journal of Molecular Sciences