Thymalin: what the studies show, status and safety
Summary
Thymalin is not a single molecule but a mixture of peptides extracted from the thymus glands of calves. It is approved and prescription-only in Russia, and in no other market checked for this page. It has no defined structure, and therefore no formula, no registry number and no database entry of its own. The identifier circulating under its name in peptide lists belongs to a different substance. The claims made for it rest on a small, unregistered body of work, published mostly in Russian before 2000 by the group that developed it.
Key findings at a glance
- It is an extract, not a defined peptide. The raw material is the thymus gland of calves and cattle under one year old, processed so that large proteins break down and fragments below 10 kDa survive [1], [2].
- The identifier found in peptide directories belongs to another substance. Asking PubChem for the name returns record 3085284, titled Nonathymulin, which describes thymulin: a defined nine-unit peptide with the formula C33H54N12O15, a mass of 858.9 and the registry number 63958-90-7 [3].
- No international code was ever assigned. The Russian label gives only the group code L03AX, under which the WHO index lists 23 substances, none of them this one [4], [5].
- One country has approved it. Russia registered it by Soviet ministerial order on 10 November 1982 and renewed the authorisation on 21 June 2024, prescription-only. Five register checks elsewhere on 17 September 2026 returned nothing, each alongside a control substance that was found [4], [2], [6], [7], [8].
- The longevity claim rests on one paper, published twice, in Russian in 2002 and in English in 2003. Its larger arm spread 94 people across four groups, so 22 to 24 each [2], [9].
- The one trial in hospital patients missed its primary endpoints, p = 0.41 and p = 0.43, in 80 patients at one centre [10].
What it is
Thymalin is an organ extract. Thymus glands from calves and young cattle are processed so that large proteins are broken down and short peptides survive; the developers describe the cut-off as 10 kDa. What remains is a mixture, and the mixture is the product [2], [1].
This makes it a different kind of thing from the peptides it is usually listed beside, which are single molecules with a sequence. Thymalin has no sequence to give, because it is not one substance but many, in proportions that depend on the batch [2].
Three short peptides were later isolated from it and developed as their own preparations: the dipeptides Glu-Trp and Lys-Glu and the tripeptide Glu-Asp-Pro. Those are defined molecules; the extract they came from is not [13].
It was developed by Vyacheslav Morozov and Vladimir Khavinson at the Military Medical Academy in Leningrad, later at the St Petersburg Institute of Bioregulation and Gerontology — an institution that appears as sponsor, author and advocate throughout the literature [2].
Quick facts
| Field | Value | Ref |
|---|---|---|
| Name | Thymalin, Russian Тималин; no international non-proprietary name was ever assigned | [4] |
| Other names | Timalin, Thymalinum, thymus extract as the Russian drug-group term | [1] |
| Class | Immunostimulant of animal origin; an organ extract, not a synthetic or recombinant peptide | [1] |
| Structure | None. A mixture of thymus polypeptides, manufacture retaining fragments below 10 kDa | [2] |
| Formula and mass | None exist. A mixture has neither | [2] |
| Half-life | Never published. The label carries no pharmacokinetics section at all | [1] |
| Route in studies | Intramuscular injection | [1] |
| Status | Approved and prescription-only in Russia; not approved in the seven reference markets | [4], [6] |
| Developed by | Vyacheslav Morozov and Vladimir Khavinson, Military Medical Academy, Leningrad | [2] |
| Marketing authorisation holder | Samson-Med, St Petersburg | [4] |
| CAS, PubChem, UNII, InChIKey | None. Values circulating under this name describe thymulin | [3] |
| WHO code | None assigned. The label states the group code L03AX only | [4], [5] |
| Storage per label | Dry, protected from light, not above 20 degrees Celsius; shelf life three years | [1] |
How it works
No mechanism has been established, and for a mixture the usual tools do not apply: there is no receptor binding profile, because there is no single molecule to bind [1].
- The label describes an effect, not a mechanism. It states that the preparation restores disturbed immunological reactivity and regulates the number and ratio of T and B lymphocytes — a summary of claimed activity [1].
- No pharmacokinetics exist. Three independent reproductions of the Russian label were checked, and none has a section on absorption, distribution, metabolism or elimination [1].
- The modern hypothesis is epigenetic. Since around 2017 the developing group has proposed that the short peptides in the extract bind to double-stranded DNA and to histones inside the cell nucleus, and so influence which genes are read [14].
- That hypothesis was tested on the isolated peptides, not on the extract. The 2023 work models and measures Glu-Trp and Lys-Glu. Whether those peptides reach any cell nucleus after the extract is injected into a person has not been shown [14].
- A laboratory study reports a shift in cell markers. In cultured human blood stem cells, two markers of immaturity (CD44 and CD117) fell two- to threefold while a marker of mature T cells (CD28) rose 6.8-fold. The authors read this as a push towards differentiation [15].
What the studies found
Most of what exists is old, small and Russian, and the volume of publication is easy to mistake for a volume of evidence [11].
All 293 PubMed records for the term, retrieved and classified on 17 September 2026 by decade of publication. Roughly four fifths appeared before the year 2000. Source [11].
Of the 293 records, 254 are in Russian, 30 in English, 8 in Ukrainian and one in German, and 100 name Khavinson or Morozov as an author [11].
Publication types as tagged in PubMed on 17 September 2026, against the number of studies found in ClinicalTrials.gov on the same day. The control query for thymus extract returned 426 register entries, so the empty result is a real absence. Sources [11], [12].
The study behind the longevity claim
Controlled clinical study One publication carries almost the whole claim, in two arms: 94 women aged 66 to 94 in a veterans' home in St Petersburg from 1996 to 2001, and 152 men and women in Kyiv treated between 1992 and 1994 and followed to 1999 [2].
The same data had appeared in Russian a year earlier. The English version does not identify itself as a second publication, and citation lists sometimes count the two as separate evidence [9].
The design is thin where it matters most. The St Petersburg arm divides 94 people into four groups of 22 to 24: placebo, this substance, the pineal preparation epithalamin, and both together. Only one arm therefore tests the substance on its own. The paper calls the trial double blind, but describes no blinding procedure and no check on whether blinding held [2].
Controlled clinical study Statistical reporting is weaker still. The paper gives percentages and fold-ratios against blanket thresholds (P less than 0.03 and P less than 0.001), with no confidence intervals, no survival curves and no time-to-event analysis. Six statistical tests are listed without saying which was used where, and nothing is reported about people who dropped out or were lost over six to eight years in a group aged 66 to 94 [2].
Forty-four parameters were measured in four groups: 17 immune, 8 endocrine and 19 metabolic. No correction for multiple testing is reported. With that many comparisons, some will separate by chance alone [2].
No primary endpoint was set in advance, and a register query on 17 September 2026 returned no record against a control query returning 426 [12], [2].
The paper carries no ethics approval statement, no funding statement and no declaration of competing interests. The authors developed the substance and led the institution behind it [2].
Why the most-quoted figure does not hold
Not randomised The single most repeated result does not come from the randomised part of the study at all. It comes from a separate group of 20 people, ten women and ten men, who received this substance together with epithalamin every year across the whole six-year period. The number quoted for the substance is therefore not a number for the substance alone [2].
That group sits outside the four-group allocation, starts at a lower average age of 79.4 against 80.2 years, and includes men, while the randomised groups are women only. It is nonetheless compared against the same control group [2].
There is a deeper problem than group matching. Anyone still being treated in the sixth year has necessarily survived those six years, so long survival is a condition of that exposure rather than only a possible consequence of it. This pattern, called immortal time bias, reliably makes a treatment look protective, and it is why such a group cannot be read against a randomised control group [2].
A second endpoint that compares a group with itself
Controlled clinical study A frequently quoted result on respiratory illness is a within-group comparison. The footnote to the table states that the marker denotes significance against the group's own baseline value, not against the control group [2].
The treated group also started with the highest baseline value of the three. When a group happens to start at an extreme value, later measurements tend to drift back towards the average on their own, with no treatment involved; statisticians call that regression to the mean. No direct comparison between the groups is reported here, yet secondary literature circulates the change as an effect of the substance [2].
The trial in hospital patients
Randomised, single-blind In 2020 a group in Chita ran a single-centre trial in 80 patients hospitalised with severe COVID-19, average age about 62. An independent statistician handled allocation; the comparator was saline [10].
It missed the endpoints it had named as primary. Time to clinical improvement gave p = 0.41, and the imaging endpoint at day 14 gave p = 0.43. The results that made the study widely quoted were secondary ones [10].
The groups did not start level. Invasive ventilation was in place for 45.4 per cent of the control group against 25 per cent of the treated group, p = 0.06, and baseline lymphocyte counts also favoured the control group, at 0.89 ± 0.12 against 0.61 ± 0.09 times ten to the ninth per litre. Neither difference is formally significant, but in a trial of 80 people a gap of that size in the strongest predictor of outcome is a serious confounder, and no adjustment for it is reported [10].
The trial was never preregistered and reports no sample size calculation. Its authors declare no competing interests, although one of them directs the institute that developed the substance [10], [12].
Reporting inconsistency A follow-up paper from the same group gives two different hospital mortality figures for the same treated group in its English and its Russian abstract, and both differ from the figure in the 2021 report [17], [10].
Laboratory and animal work
Animal data, independent A Ukrainian group unconnected to the developers studied jaw defect healing in 48 adult rats, in four groups of twelve, reporting changes in local immune cell populations over 28 days without numerical values in the abstract [18], [19].
Laboratory data A group in Vladivostok used the preparation as the reference against which another peptide product was measured; both raised cytokine production in cultured blood cells, so here the substance is the yardstick rather than the thing tested. Separately, the isolated dipeptides have been modelled against DNA and tested in an inflammation model — mechanism work on components, not evidence for the extract [20], [14].
What is still unknown about Thymalin
- What the body does with it. No absorption, distribution, half-life or elimination data exist in any species, and the label has no such section [1].
- What is actually in a given batch. Composition is set by the process rather than by a specification; no independent analysis of batch-to-batch variability exists, and none of a vial sold online [2], [21].
- Whether the immune system reacts to it. No immunogenicity data exist, despite repeated injection of a foreign protein mixture [13].
- Whether any human finding replicates. No group outside the post-Soviet research space has ever studied it: no work from western Europe, North America, Australia, Japan or China [11].
- What the modern hypothesis would predict. Nobody has shown that the short peptides reach a cell nucleus after the extract is injected [14].
Side effects and safety
The safety record is thin rather than reassuring: the Russian label names one adverse effect, in one word [1].
- Allergic reactions are the only adverse effect listed, with no frequency category and no tabulated summary of the kind expected today [1].
- Three contraindications are stated: individual hypersensitivity, pregnancy and breastfeeding. There is no section on interactions with other medicines [1].
- The source material carries a theoretical transmission risk. The developers name it themselves: material of animal origin may carry prions, infectious agents or nucleic acids. Their reassurance that testing found none comes from the manufacturing side [2].
- A frequently quoted phrase is not a safety finding. The statement that the preparation has practically no side effects comes from a review by the developing group, and summarises impressions rather than collected safety data [13].
- The American regulator raised paediatric marketing specifically. Its 2024 letter to a seller states that it is particularly concerned that the product was marketed for use in children. [21].
- Grey-market material is not the registered product. What is sold online sits outside any pharmaceutical quality system, which matters more for an undefined mixture than for a synthetic molecule [21].
Why this page lists no doses
This page gives no amounts for Thymalin, in any unit, and no course lengths, injection intervals or repetition schedules. It is a prescription-only medicine where it is approved, and its label reserves the decision to a prescriber [1].
Where a preparation is authorised in one market and unauthorised everywhere else, a figure on a reference page would function as an instruction rather than a citation, whether it comes from a label or from a study table. The same reasoning covers reconstitution and injection. Nothing here is written to be carried out [4].
Development and approval status
Thymalin has been an approved medicine in one country since 1982 and has never been assessed anywhere else. There was no western phase 1, 2 or 3 programme, because there was never a western application [2], [4].
Four decades in one country
- 1982Soviet approvalApproved for medical use as an immunomodulator by ministerial order number 1008 of 10 November, registration 82.1008.8
- 1992-1999The Kyiv arm152 participants treated between 1992 and 1994 and followed to 1999; results published later
- 1996-2001The St Petersburg arm94 participants in a veterans home, observed over six years; the basis of the longevity claim
- 2002-2003Published twiceThe same data appear in Russian in 2002 and in English in 2003, without the second being marked as such
- 2010Russian registrationRegistration LS-000267 of 26 February, named in the primary literature
- 2020-2021The hospital trialSingle-centre trial in 80 patients, never entered in a trial register; primary endpoints missed
- 2024Renewed, and rebukedRussian registration renewed on 21 June; in February the American regulator names the product in a warning letter
The dates behind the timeline are the Soviet order number 1008 of 10 November 1982 with registration 82.1008.8, the Russian registration LS-000267 of 26 February 2010, the warning letter of 7 February 2024, and the current registration of 21 June 2024, granted without expiry to Samson-Med of St Petersburg [2], [10], [21], [4].
| Market | Status | Since or note |
|---|---|---|
| Russia | Approved | Prescription-only; current registration June 2024 |
| United States | Unapproved | Named in a 2024 warning letter |
| European Union | Unapproved | No assessment report |
| Germany | Unapproved | Not marketable |
| United Kingdom | Unverified | Register unreadable |
| Australia | Unverified | Not scheduled |
| Canada | Unapproved | No product record |
| Switzerland | Unapproved | None found |
Five of these entries rest on register queries run on 17 September 2026 alongside a control substance in the same database, so a blank result means absence rather than a broken query. Two are weaker and are marked as such: the British register returns results only through scripts that could not be read, and the Australian product database was unreachable that day, leaving only the Australian scheduling instrument fully searchable [6], [7], [8], [22], [23], [24], [25].
The registered Russian indication is stated on the label as immunodeficiency states — a statement about what the authorisation covers, not about what the substance achieves [1].
In the United States it appears on no list of bulk substances nominated for pharmacy compounding, so there is no lawful route to make it for people. In Germany, importing an unauthorised medicine is limited to single-patient supply on prescription through a pharmacy, which does not cover a private import. See are peptides legal and FDA-approved peptides [26], [6], [23].
Anti-doping
Thymalin is not named on the 2026 prohibited list. A full-text search on 17 September 2026 found only two near matches, both concerning thymosin beta-4 and its derivatives under class S2.3 [27].
The annex to the German anti-doping statute and the Australian poisons standard gave the same result: thymosin beta-4 and somatropin are listed there, this substance is not, and control searches in both documents returned matches, so the absence is real [28], [25].
Absence from a list is not a clearance. An athlete injecting a preparation that no regulator has assessed still carries the contamination risk, and strict liability makes it their own. See peptides banned in sport [27].
Compared with related peptides
| Substance | What it is | Defined structure | Status | Ref |
|---|---|---|---|---|
| Thymalin | Calf thymus extract, a mixture | No | Approved in Russia only | [4] |
| Thymosin Alpha-1 | Synthetic 28-unit peptide, international name thymalfasin | Yes, C129H215N33O55, 3108.3 | Approved medicine in some markets; WHO code L03AX25 | [16], [5] |
| Thymopentin | Synthetic five-unit peptide, a fragment of thymopoietin | Yes, C30H49N9O9, 679.8 | WHO code L03AX09 | [16], [5] |
| Thymulin | Defined nine-unit thymic peptide, also called FTS | Yes, C33H54N12O15, 858.9 | Not a marketed medicine | [3] |
| TB-500 | Fragment related to thymosin beta-4 | Yes, see its own page | Prohibited in sport | [27] |
The table shows what the shared syllable hides. Four of these five are single molecules with a formula, a mass and a registry number; one is a mixture with none of those things, and two of the comparators hold WHO codes of their own where Thymalin holds only a group code on a label [3], [16], [5].
That difference is not cosmetic: evidence attaches to a defined molecule and travels with it, while evidence about a mixture is tied to the process that made it, so results for thymosin alpha-1 or thymopentin say nothing about this preparation. TB-500 is the only entry here named on the prohibited list, through its parent molecule, which has led to this substance being assumed prohibited by association [5], [27].
Common misconceptions
- "Thymalin has the formula C33H54N12O15 and a mass of 858.9." Those values belong to thymulin, a defined nine-unit peptide. The name sits in that record only among more than thirty depositor synonyms [3].
- "Thymalin is a peptide like the others in the register." It is an extract from bovine tissue, with no sequence and no single mass [2], [1].
- "Thymalin and Thymosin Alpha-1 are two names for the same thing." They are unrelated products: Thymosin Alpha-1 is synthetic and defined, carries the international name thymalfasin and has its own WHO code [16], [5].
- "Thymogen, Vilon and Crystagen are other names for Thymalin." They are the single peptides isolated from the extract and then made synthetically, each its own preparation. Findings for them are not findings for the mixture [13].
- "The famous 15-year follow-up proves what Thymalin does." That study examined epithalamin, a pineal gland preparation, in 39 against 40 patients. This substance does not appear in it [29].
- "It has been registered in Russia since 1992." That date circulates widely but could not be traced to a primary source. Documented are the Soviet approval of 1982 and the Russian registrations of 2010 and 2024 [2], [10], [4].
- "Thymi extractum on European medicine lists is the same thing." That term means extract of the culinary herb thyme and appears in cough preparations. The overlap is in the name only [22].
- "It appears in every peptide warning letter." A 2026 letter to a different seller names other peptides and not this one; the 2024 finding was specific [30].
Frequently asked questions
What is Thymalin?
It is an extract, not a defined peptide: a mixture of polypeptides taken from the thymus glands of calves and young cattle, made so that fragments below 10 kDa survive. A mixture has no single structure, so Thymalin has no sequence, no formula and no molecular mass. That is a fact about the substance, not a gap in the record.
Does Thymalin have a CAS number or a PubChem entry?
No. Searching PubChem returns compound 3085284, but that record is titled Nonathymulin and describes thymulin, a defined nine-unit peptide with the CAS number 63958-90-7. The name Thymalin sits there only among more than thirty depositor synonyms. No record exists for the extract itself, and a mixture could not be represented in a structure database anyway.
Is Thymalin approved anywhere?
In Russia only, as a prescription-only medicine. Soviet approval dates from an order of 10 November 1982, and the current registration was granted on 21 June 2024. Checks on 17 September 2026 found no authorisation in the United States, the European Union, Germany, Canada or Switzerland; the British and Australian registers could not be read.
How strong is the longevity claim made for Thymalin?
It rests on a single paper, published twice: in Russian in 2002 and in English in 2003. Its larger arm spread 94 participants across four groups, gave no confidence intervals, measured 44 parameters without correcting for multiple testing, and carried no ethics or conflict-of-interest statement. The authors were the developers.
Why is the most-quoted Thymalin result unreliable?
Because it comes from a group that was not randomised, and did not receive the substance alone. Twenty people, ten women and ten men, had it together with the pineal preparation epithalamin every year for six years, and were then compared against the randomised control group, which held women only. Anyone still being treated in the sixth year has by definition survived six years — a circularity known as immortal time bias.
What happened in the Thymalin trial in COVID-19 patients?
It missed the endpoints it had named as primary: time to clinical improvement returned p = 0.41 and the imaging endpoint at day 14 returned p = 0.43. The results that made it popular were secondary. The trial was single-blind, ran at one centre with 80 participants, was never preregistered and reported no sample size calculation. One of its authors directs the institute that developed the substance.
Is Thymalin the same as Thymosin Alpha-1 or Thymopentin?
No. Thymosin Alpha-1 is a synthetic 28-unit peptide with the international name thymalfasin and the WHO code L03AX25; thymopentin is a synthetic five-unit peptide with the code L03AX09. Both have a formula, a mass and a registry number. Thymalin has none of these, so evidence for those two says nothing about it.
Is Thymalin banned in sport?
It is not named on the 2026 prohibited list, in the annex to the German anti-doping statute, or in the Australian poisons standard; all three were searched in full on 17 September 2026, and the only near matches concern thymosin beta-4. Absence from a list is not a clearance: an athlete injecting an unapproved preparation still carries the contamination risk under strict liability.
Sources
- MEDI RU. Тималин — official Russian package insert, reproduced in full (state of the printed leaflet 1 October 2011). Composition, pharmacological description, indications, contraindications, adverse effects, storage, shelf life and the dispensing status "По рецепту" (on prescription). Retrieved 17 September 2026. https://medi.ru/instrukciya/timalin_738/
- Khavinson VKh, Morozov VG (2003). Peptides of pineal gland and thymus prolong human life. Neuro Endocrinology Letters 24(3-4):233-240. PMID 14523363. The title states the authors' claim; this page does not adopt it. Full text read page by page from a scanned copy: manufacturing and the 10 kDa cut-off and the Soviet registration on p. 234, design on p. 236, the tables on p. 238, the statistics paragraph and the absence of an ethics, funding or competing-interest statement on p. 239. https://khavinson.info/downloads/2003-Khavinson_Morozov.pdf
- PubChem PUG-REST, queried 17 September 2026. The name query for "thymalin" resolves to compound 3085284, whose record is titled Nonathymulin, with formula C33H54N12O15, mass 858.9, InChIKey LIFNDDBLJFPEAN-BPSSIEEOSA-N, CAS 63958-90-7 and UNII 9H198D04WL — that is thymulin. The name appears there only among more than thirty depositor synonyms. The stereochemically defined thymulin record is compound 71300623. https://pubchem.ncbi.nlm.nih.gov/rest/pug/compound/cid/3085284/synonyms/JSON
- Vidal Rossija. Тималин, product information sheet 23838, held as a mirror of the Russian state register. Registration ЛП-№(005867)-(РГ-RU) granted 21 June 2024 without expiry; marketing authorisation holder Samson-Med, St Petersburg; group code L03AX. Retrieved 17 September 2026. https://www.vidal.ru/drugs/thymalin__23838
- WHO Collaborating Centre for Drug Statistics Methodology. ATC/DDD Index, group L03AX (other immunostimulants), state of 20 January 2026. The group holds 23 substances, among them L03AX09 thymopentin and L03AX25 thymalfasin. Neither thymalin nor thymus extract is among them, so the group code on the Russian label is not an assigned code. https://atcddd.fhi.no/atc_ddd_index/?code=L03AX
- US Food and Drug Administration, openFDA. Four queries on 17 September 2026 — approvals, the national drug code directory, product labelling and enforcement reports — each returned no record for the name. The identical control query for tesamorelin returned one approval record the same day, so the method works and the empty result is real. https://api.fda.gov/drug/drugsfda.json
- European Medicines Agency. Complete medicines report and orphan designations report, both downloaded and searched in full on 17 September 2026: no match for thymalin, timalin, thymosin or thymopentin, against one match each for the control substances tesamorelin and tirzepatide. https://www.ema.europa.eu/en/medicines/download-medicine-data
- Health Canada. Drug Product Database, active ingredient endpoint, queried 17 September 2026: empty result. The control query for tesamorelin returned two records the same day. A query for "thymus" returns only three homeopathic tissue preparations. https://health-products.canada.ca/api/drug/activeingredient/?ingredientname=thymalin
- Khavinson VKh, Morozov VG (2002). Geroprotective effect of thymalin and epithalamin. Advances in Gerontology 10:74-84, in Russian. PMID 12577695. The Russian first publication of the same data that appeared in English a year later.
- Kuznik B, Khavinson V, Shapovalov K, Linkova N, Lukyanov S, Smolyakov Yu, et al. (2021). Peptide drug thymalin regulates immune status in severe COVID-19 older patients. Advances in Gerontology 11(4):368-376. DOI 10.1134/S2079057021040068. PMC8654498. Full text read: 80 participants at one centre, single-blind with saline control, ethics approval number 102 of 15 May 2020, the named primary endpoints and their results (p = 0.41 for time to clinical improvement, p = 0.43 for imaging at day 14), the baseline imbalance in invasive ventilation (45.4 against 25 per cent, p = 0.06) and in lymphocyte count, the citation of the Russian registration LS-000267 of 26 February 2010, and the authors' statement that they declare no conflict of interests.
- NCBI PubMed E-utilities, queried 17 September 2026 for the term "thymalin": 293 records, all of them retrieved and classified. By language 254 Russian, 30 English, 8 Ukrainian and 1 German; by decade 125 in the 1980s, 108 in the 1990s, 42 in the 2000s, 10 in the 2010s and 8 in the 2020s; 100 records list Khavinson or Morozov as an author. By publication type: 12 tagged clinical trial, 9 review, 5 case reports, 2 controlled clinical trial and 2 randomised controlled trial. https://eutils.ncbi.nlm.nih.gov/entrez/eutils/esearch.fcgi?db=pubmed&term=thymalin
- ClinicalTrials.gov API v2, queried 17 September 2026 by term and by intervention: zero studies in both cases. The control query for "thymus extract" returned 426 studies, so the interface was working. https://clinicaltrials.gov/api/v2/studies?query.term=thymalin
- Khavinson VKh, Linkova NS, Chalisova NI, Ivko OM (2021). The use of thymalin for immunocorrection and molecular aspects of biological activity. Biology Bulletin Reviews 11(4):377-382. DOI 10.1134/S2079086421040046. PMC8365293. Full text read: origin of the raw material, identification of the short peptides Glu-Trp, Lys-Glu and Glu-Asp-Pro by chromatography and mass spectrometry, and the summary phrase about side effects quoted on this page.
- Linkova N, Khavinson V, Diatlova A, Petukhov M (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. International Journal of Molecular Sciences 24(17):13377. PMID 37686182. PMC10488166. Evidence that the epigenetic hypothesis was tested on the isolated dipeptides rather than on the extract.
- Khavinson VK, Linkova NS, Kvetnoy IM, Polyakova VO (2020). Thymalin: activation of differentiation of human hematopoietic stem cells. Bulletin of Experimental Biology and Medicine 170(1):118-122. PMID 33237528. PMC7686446. Cell culture work: CD44 and CD117 expression lowered two- to threefold, CD28 expression raised 6.8-fold.
- PubChem PUG-REST, identifiers of the neighbouring substances, queried 17 September 2026: thymopentin compound 451417, C30H49N9O9, mass 679.8; thymosin alpha-1 compound 16130571, C129H215N33O55, mass 3108.3. https://pubchem.ncbi.nlm.nih.gov/rest/pug/compound/name/thymopentin/property/MolecularFormula,MolecularWeight,InChIKey/JSON
- Kuznik BI, Shapovalov KG, Smolyakov YN, Lukyanov SA (2022). Morphological compound and indicators of the blood clotting system in severe COVID-19 patients of middle aged and elderly during treatment with tocilizumab and thymalin. Advances in Gerontology 35(3):368-374, in Russian. PMID 36169363. Used here only as evidence of inconsistent reporting: the English and Russian abstracts of the same paper state different hospital mortality figures for the treated group, and both differ from the figure in the 2021 report.
- Boiko AA, Malanchuk VA, Myroshnychenko MS (2024). Reparative osteogenesis in mandible in cases of filling a bone defect with hydroxyapatite-containing osteotropic material and injecting the surrounding soft tissues with thymalin. Wiadomości Lekarskie 77(1):68-76. DOI 10.36740/WLek202401110. PMID 38431810. Independent Ukrainian group, 48 rats in four groups of twelve.
- Boiko AA, Malanchuk VA, Myroshnychenko MS, Markovska OV (2024). Expression features of T-lymphocytes, B-lymphocytes and macrophages in the post-traumatic regenerate of the mandible in rats. Polski Merkuriusz Lekarski 52(2):171-177. DOI 10.36740/Merkur202402105. PMID 38642352. Companion publication from the same independent group.
- Kuznetsova TA, Besednova NN, Zaporozhets TS, Smolina TP, Kazha AK (2013). Comparative study of immunomodulatory activity of the peptides tinrostim and thymalin. Antibiotiki i Khimioterapiya 58(11-12):8-12, in Russian. PMID 24734422. Independent group in Vladivostok; thymalin serves as the reference preparation, not as the substance under test.
- US Food and Drug Administration. Warning letter to US Chem Labs, Miami, Florida, 7 February 2024, reference MARCS-CMS 669074. Names the product by name alongside two prescription medicines, quotes the seller's own website claims, states that the agency is particularly concerned that the product is marketed for use in children, and rejects the research-use-only labelling. Violations cited under sections 505(a), 301(d), 502 and 301(a) of the Federal Food, Drug, and Cosmetic Act. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/us-chem-labs-669074-02072024
- Swissmedic. Register of authorised human medicines and the extended medicines list, both downloaded and searched in full on 17 September 2026: no match for thymalin, timalin, thymopentin or thymosin, against control matches for Genotropin, Mounjaro, Ozempic, somatropinum and tirzepatidum. The only near match, thymi extractum, is extract of the herb thyme. https://www.swissmedic.ch/
- Germany. Annex 1 to the medicines prescription ordinance, full text checked 17 September 2026: no entry for the name, against a control match for somatropin. Absence from that annex does not make an unauthorised medicine marketable; placing one on the market falls under section 21 of the medicines act, and import is limited to single-patient supply on prescription through a pharmacy under section 73(3). https://www.gesetze-im-internet.de/amvv/anlage_1.html
- United Kingdom. The medicines regulator's product search was queried on 17 September 2026 and returned a page whose result list loads only through scripts; the underlying search interface answered with an access error. The status given here is inferred from the worldwide picture, not from a register match. https://products.mhra.gov.uk/search/?search=thymalin
- Australia. Therapeutic Goods (Poisons Standard — June 2026) Instrument 2026, register number F2026L00633, full text searched 17 September 2026: no match for thymalin, thymus or thymopentin, against control matches for somatropin and thymosin beta-4. The separate product register was unreachable that day, so a registration could be neither confirmed nor excluded. https://www.legislation.gov.au/F2026L00633
- US Food and Drug Administration. Bulk drug substances used in compounding under section 503A of the Federal Food, Drug, and Cosmetic Act, overview page retrieved 17 September 2026. The strings thymalin, thymus and thymosin do not appear in it. https://www.fda.gov/drugs/human-drug-compounding/bulk-drug-substances-used-compounding-under-section-503a-fdc-act
- World Anti-Doping Agency. The 2026 Prohibited List, in force 1 January 2026, searched in full on 17 September 2026. Two matches for the string "thym", both concerning thymosin beta-4 and its derivatives under class S2.3. Neither the name nor thymus extract nor thymic peptide appears anywhere in the document. https://www.wada-ama.org/en/prohibited-list
- Germany. Annex to section 2(3) of the anti-doping act, official citation Federal Law Gazette 2023 I no. 67, full text searched 17 September 2026. The only match for "Thym" is thymosin beta-4 and its derivatives under section II number 3. https://www.gesetze-im-internet.de/antidopg/anlage.html
- Korkushko OV, Khavinson VKh, Shatilo VB, Antonyk-Sheglova IA (2011). Peptide geroprotector from the pituitary gland inhibits rapid aging of elderly people: results of a 15-year follow-up. Bulletin of Experimental Biology and Medicine 151(3):366-369. PMID 22451889. The study concerns epithalamin in 39 against 40 patients; thymalin does not appear in it.
- US Food and Drug Administration. Warning letter to Wholesale Peptide, Brooksville, Florida, 17 June 2026, reference MARCS-CMS 729447. Used as a negative control: it names other peptides and not this one. https://www.fda.gov/inspections-compliance-enforcement-and-criminal-investigations/warning-letters/wholesale-peptide-729447-06172026
Cite this page
The facts on this page were checked on 17 September 2026, and every register behind the status table was queried on that day. Two entries could still move: the British and Australian product registers could not be read, and the Russian state register itself is behind a captcha, so its details rest on two independent reproductions of the label.
myPeptides Research & Editing. (2026). Thymalin: what the studies show, status and safety. Version 1.0, 17 September 2026. myPeptides Peptide Register. Retrieved from https://mypep.app/peptides/thymalin
How pages in this register are compiled and graded is described under methodology; the full register is at peptides.
| Version | Date | Change |
|---|---|---|
| 1.0 | 2026-09-17 | Initial publication |
Last verified: 17 September 2026. Next review: on any registered trial, on any independent replication, on any change to the Russian authorisation, or on any change to the anti-doping classification.