Skip to content
PeptideAI
Human trialsimmunelongevityinflammationrecovery

Thymalin (Cytomax)

Calf-thymus peptide extract used in ten-day courses to restore T-cell function in ageing or post-illness immune systems, and the compound with the strongest human survival signal in the entire bioregulator series.

Also known as Timalin, Thymalinum, thymus peptide extract, thymus extract bioregulator, Cytomax thymus, Thymalin, Vladonix

Human trials — Studied in people, typically early phase or small — promising rather than proven.

Thymalin has decades of Russian clinical use and appears in the same 266-person, six-to-eight-year mortality cohort as Epithalamin, where the combination arm showed the largest survival benefit. There are also Russian reports of improved immune markers in elderly and post-surgical patients. None of it has been replicated outside Khavinson's institute, and the trials predate modern registration and blinding standards.

How it works

Thymalin is an acid extract of calf thymus containing peptides broadly in the 1-10 kDa range, so it overlaps compositionally with the material that thymosin alpha-1 and thymopoietin were originally isolated from. Russian clinical work reports restoration of T-cell counts, improved CD4/CD8 ratio, increased lymphocyte proliferative response and normalisation of interleukin profiles in elderly and post-surgical patients. The synthetic dipeptide Vilon (Lys-Glu) was later isolated as a putative active core. As with all Cytomaxes, no single receptor interaction has been demonstrated and the composition is not standardised by any Western pharmacopoeia.

Targets: Thymus, T-lymphocyte maturation, CD4/CD8 ratio, Interleukin signalling

Dosing

ProtocolDoseFrequencyRoute
Standard Russian immune courseAny time of day; no chronobiology attached to this one.10 mgonce daily for 5 to 10 consecutive daysintramuscular
Subcutaneous longevity courseAny time of day.5 mg – 10 mgonce daily for 10 dayssubcutaneous
  • · 10 mg per day for 5-10 days is the dose used throughout the clinical literature. Repeat once or twice a year.
  • · Commonly run alongside Epithalamin in longevity protocols, mirroring the combination arm of the mortality cohort.

Cycling

Ten-day courses, one to two per year. The strongest human data came from repeating the course annually, not from continuous use.

Work out your exact syringe units →

Pharmacology

Half-life
Not measured; the constituent peptides are expected to clear from plasma within minutes to hours, with any immune effect long outlasting the exposure.
Onset
Immune markers in the Russian literature shift over the course of a 5-10 day run; subjective changes in infection frequency are framed over months.
Routes
intramuscular, subcutaneous
Molecule
Calf thymus-derived low-molecular-weight polypeptide complex

Handling

Diluent
Bacteriostatic water or sterile saline
Typical mix
1 or 2 mL
Vial sizes
10 mg
Lyophilised
Refrigerate at 2-8 C as the manufacturer specifies; do not treat this like a room-temperature-stable synthetic peptide.
Reconstituted
Refrigerated, used within about 7-10 days.
Light sensitive
Yes — keep it out of the light

Mixing

A 10 mg vial in 1 mL gives one full insulin syringe per daily dose, which keeps a short course simple.

Side effects

  • commonInjection-site soreness— Typical of intramuscular dosing.
  • uncommonTransient flu-like feeling or low-grade fatigue— Reported early in a course and generally self-limiting.
  • rareAllergic reaction to bovine protein— Real possibility with animal-tissue extract.
  • rareTheoretical flare of autoimmune disease— An immune-stimulating agent in someone with autoimmunity is a genuine risk, not a disclaimer.

Do not use if

  • Active autoimmune disease - this is an immune stimulant and can push the wrong direction.
  • Solid organ transplant or any deliberate immunosuppression - directly opposes the therapy.
  • Known bovine protein allergy.
  • Pregnancy and breastfeeding - no data.
  • Unverified-source product: animal-tissue extracts carry a theoretical prion risk that synthetics do not.

Combining it

  • synergyepithalamin — The Thymalin plus Epithalamin pairing produced the largest reported mortality reduction in the Khavinson cohort.
  • redundantthymosin-alpha-1 — Thymosin alpha-1 is a defined synthetic thymic peptide from the same source tissue; running both is redundant, and the synthetic has far better evidence.
  • redundantvilon — Vilon is the synthetic dipeptide isolated from this extract.
  • conflictimmunosuppressants — Directly opposed pharmacology - do not combine with ciclosporin, tacrolimus, or biologic immunosuppression.

What to monitor

  • · A CBC with differential before and a few weeks after a course is the one genuinely informative test here.
  • · If you have any autoimmune history, watch for symptom flare during the first course.

Legal status

A registered medicine in Russia; not approved in the US, UK or EU. Sold in the West as a research chemical or as a capsule supplement under the Vladonix name.

References

  • Khavinson & Morozov 2003, peptides of pineal gland and thymus prolong human life (Neuroendocrinology Letters) (trial)
  • Khavinson & Malinin, Gerontological Aspects of Genome Peptide Regulation (Karger monograph) (review)
  • Anisimov & Khavinson, peptide bioregulation of aging: results and prospects (Biogerontology) (review)

Mechanism in depth

The most concrete mechanistic result Thymalin has is a flow cytometry experiment, not a receptor study. Khavinson's group exposed human haematopoietic stem cells to Thymalin and reported that CD44 and CD117 - the stem and intermediate-progenitor markers - fell two- to threefold while CD28, the mature T-lymphocyte costimulatory marker, rose 6.8-fold. The interpretation is that Thymalin pushes CD117-positive progenitors down the maturation path to CD28-positive T cells rather than stimulating existing lymphocytes. That is a coherent story for why the clinical claims are about immunosenescence and post-illness recovery rather than about acute immune stimulation: it takes weeks, it works on the supply line rather than the effector pool, and it should do more in someone whose thymic output has collapsed than in a healthy 30-year-old. The second strand is signal transduction. Thymic short peptides were reported to drive thymocyte blast transformation through the sphingomyelin pathway - sphingomyelinase, ceramide, downstream kinase activation - rather than through a classical receptor-ligand event, and to raise interleukin-2 transcription in splenocytes and in rat hypothalamic tissue. The IL-2 finding is the mechanistic link between the immune claims and the neuroendocrine ones. A 2022 Italian collaboration in THP-1 monocytes found that Thymalin, along with the rest of the Khavinson set, increased tyrosine phosphorylation of mitogen-activated cytoplasmic kinases and suppressed LPS-driven TNF and IL-6 release. Note the direction of that last result: in a monocyte model these peptides are anti-inflammatory and induce TNF tolerance, which sits awkwardly beside the popular framing of Thymalin as a pure immune stimulant. The compound looks more like an immune modulator that can move you either way depending on where you started.

What usually goes wrong

The realistic harm here is autoimmune. This is the one bioregulator with a plausible mechanism for making a person meaningfully worse, and it is the one where 'no reported side effects' should be read as 'thin exposure data in unblinded Russian studies' rather than as safety. Hashimoto's, psoriasis, rheumatoid disease and inflammatory bowel disease are all conditions where deliberately pushing T-cell maturation is a bad idea, and a flare four weeks after a course will not look obviously drug-related. The second failure mode is expecting an acute effect. The mechanism is progenitor differentiation, which is measured in weeks; anyone reporting that Thymalin cleared their cold in two days is describing a cold clearing. Third, the compound is bovine tissue from a grey supply chain, with the same unresolved prion question as every Cytomax. Fourth, and most specific to Thymalin: the COVID mortality result is being quoted as though it were a randomised controlled trial. It is a three-arm comparative study whose own English and Russian abstracts disagree on the headline number. That is not a reason to dismiss it and it is absolutely a reason not to quote 20.6 percent as a fact.

Bloodwork worth running

MarkerWhenWhy it matters
CBC with differential, specifically absolute lymphocyte countBaseline before the course, then two to four weeks after the last injection. Testing during the course tells you less than testing after it.This is the cheapest test that maps directly onto the claim. The COVID work reported roughly a doubling of lymphocytes and monocytes and a 1.3-fold rise in total leukocytes in severely ill patients. If Thymalin does anything measurable in you, the lymphocyte line is where to look.Act if: In a healthy adult with a normal baseline, expect no meaningful change - the reported effects came from people who were lymphopenic to start with. A falling lymphocyte count during a course is not a Thymalin effect and needs its own explanation.
CD4/CD8 ratio by flow cytometryBaseline and six to eight weeks after the course, since T-cell maturation is slow.The specific claim across the entire Russian literature is normalisation of this ratio in immunosenescence. It is the claim, so it is the test. It is also the one that will tell an older user whether they are in the population the data came from.Act if: An inverted ratio below 1.0 at baseline is the profile that the literature claims to correct. If yours is already 1.5-2.5, there is nothing here to normalise and you are dosing on faith.
hs-CRPBaseline, then two weeks after the course.The monocyte work suggests suppression of TNF and IL-6, and CRP is the cheap downstream readout of IL-6. It is also the marker that would catch the opposite outcome - an inflammatory flare in someone with quiescent autoimmunity.Act if: A rise in hs-CRP above 3 mg/L during or after a course in someone previously below 1 mg/L is a stop signal, particularly with any autoimmune history.
ANA and any disease-specific autoantibody you already carryBaseline before a first course only, and again if symptoms change.The single most plausible harm from this compound is pushing a subclinical autoimmune process into a clinical one. If you already know you have a positive ANA, thyroid antibodies or a rheumatological diagnosis, you need a before-and-after number rather than an impression.Act if: Any new or rising autoantibody titre with symptoms means stop and do not repeat courses.
D-dimer, fibrinogen and LDHNot indicated for healthy users. Relevant only if this is being used adjunctively during an acute inflammatory illness.Only relevant in the acute-illness setting the COVID work came from, where Thymalin was reported to lower fibrinogen 1.2-fold, LDH 1.8-fold and D-dimer 1.7-fold. In a healthy user these are not routine monitoring - they are listed here so you can see what the trial actually measured rather than what the vendor says it does.Act if: No self-directed threshold; anyone unwell enough for these to matter should be under clinical care.

Pharmacokinetics

Metabolism
Proteolysis by serum and tissue peptidases to smaller fragments and free amino acids. Khavinson's own later work argues that the active moieties are the dipeptides Lys-Glu and Glu-Trp liberated from or present within the complex, which if true means the extract is a prodrug for two dipeptides.
Elimination
Renal filtration of fragments; amino acids re-enter the general pool. Unmeasured.

Receptor targets

  • No identified receptor — None published

    Half a century of work has not produced a receptor, a binding constant or a saturable site for this preparation. Treat any receptor claim about Thymalin as fabricated.

  • CD117-positive haematopoietic progenitors

    Reported 2-3 fold reduction in CD44 and CD117 expression with a 6.8-fold rise in CD28, interpreted as driving progenitor differentiation into mature T lymphocytes. This is the best-characterised cellular effect the compound has.

  • Sphingomyelin signalling pathway in thymocytes

    Short thymic peptides were reported to trigger thymocyte blast transformation via sphingomyelinase-ceramide signalling rather than a surface receptor, which is the proposed route from an extracellular peptide to a proliferative response.

  • Interleukin-2 gene transcription

    Increased IL-2 mRNA in splenocytes in vitro and in rat hypothalamic structures in vivo. IL-2 is the cytokine that would plausibly underwrite the claimed lymphocyte proliferative recovery.

  • TNF-alpha and IL-6 release from LPS-stimulated monocytes

    Suppressed, with induction of TNF tolerance, in the THP-1 monocyte model. This is an anti-inflammatory effect and cuts against the simple immune-stimulant framing.

Trials

  • Khavinson & Morozov geroprotection cohort, St Petersburg (Thymalin and combination arms) Not a registered trial - open, controlled long-term cohort · n=266 · 2003

    All-cause mortality over six to eight years in people over 60. The Thymalin plus Epithalamin arm with repeated annual courses reported 4.1-fold lower mortality than control - the largest effect described anywhere in the bioregulator literature and the reason this pairing dominates longevity protocols. Unblinded, unregistered, unreplicated outside the originating institute.

  • Kuznik comparative study of Thymalin versus tocilizumab in severe COVID-19, Chita State Medical Academy Comparative clinical study, three arms, not registered as far as I can establish · 2022

    Hospital mortality and haematological/coagulation parameters in severe COVID-19 in middle-aged and elderly patients. Reported hospital mortality of 40.9 percent on standard therapy, 28.4 percent with tocilizumab and 20.6 percent with Thymalin in the English abstract. Group sizes are not given in the abstract, and - importantly - the Russian-language abstract of the same paper reports 16.2 percent for Thymalin and 28.8 percent for tocilizumab rather than 20.6 and 28.4. The two abstracts of one paper do not agree with each other.

  • Thymalin haematopoietic stem cell differentiation study In vitro, human cells · 2020

    Expression of CD44, CD117 and CD28 in cultured human haematopoietic stem cells. CD44 and CD117 fell 2-3 fold, CD28 rose 6.8-fold, interpreted as Thymalin driving progenitor differentiation into mature T lymphocytes.

What to expect, and when

Days one to ten, during the course: nothing you can feel reliably. A minority report a transient flu-like heaviness or fatigue in the first two or three days, which is self-limiting and is what you would expect from a cytokine nudge. Weeks two to four after the course: this is where the CBC and lymphocyte changes described in the literature appear. If you are going to test, test here. Weeks four to eight: CD4/CD8 changes, if any, since T-cell maturation is the rate-limiting step. Months three to twelve: the only outcome that ever mattered in the human data - frequency and severity of infection across a season. That is the endpoint to judge it on, and it takes a year and a written log to judge honestly. Years: the mortality claims, which no individual can observe.

Stacking and comparisons

Thymalin plus Epithalamin is the one combination in this class with an outcome dataset attached, run as ten-day courses once or twice a year. Everything else is convention. Do not run Thymalin alongside Vilon or Thymogen: Khavinson's own 2023 paper argues those two dipeptides are the active constituents of Thymalin, so stacking them is taking the same drug twice. Thymosin alpha-1 is the serious alternative rather than a partner - it is a defined 28-amino-acid synthetic with regulatory approvals in dozens of countries and real trial data, and if you want thymic immune support with evidence behind it, that is the compound. Running both is redundant and makes attribution impossible. The genuinely dangerous combination is with immunosuppression: ciclosporin, tacrolimus, methotrexate, TNF inhibitors, or any transplant regimen. Thymalin's stated purpose is to expand mature T-cell populations, which is precisely what those drugs exist to prevent.

Against thymosin alpha-1: not close. Thymosin alpha-1 is a defined 28-residue synthetic peptide, approved in more than thirty countries, with randomised data in hepatitis B, sepsis and vaccine adjuvancy. Thymalin is an undefined calf-thymus extract whose evidence is an unreplicated Russian cohort. Thymalin's only advantage is that it is the compound in the mortality study; on every scientific axis thymosin alpha-1 is the better-evidenced choice for thymic immune support. Against Vilon and Thymogen: those are the dipeptides Khavinson's group now says are the active fraction, so they are simplified versions of the same idea with cleaner chemistry and weaker clinical data. Against Vladonix: the same material in a capsule, with an unproven extra step. The injection has whatever evidence exists. Against no intervention: for a healthy adult under 50 with a normal CD4/CD8 ratio and normal lymphocyte count, the mechanistic case for benefit is close to zero, because there is no immunosenescence to reverse.

Rough cost

$70–$220/month. A ten-day course is ten 10 mg vials. Because the protocol is one or two courses annually rather than continuous use, annual spend is roughly one to two course prices. Indicative grey-market figures, not verified against vendor listings in this session.

Genuinely uncertain

  • No pharmacokinetic parameter has been measured for Thymalin by any route.
  • The composition of the extract is not standardised by any Western pharmacopoeia and no lot-by-lot profile is published.
  • Whether the activity resides in Lys-Glu and Glu-Trp specifically, as Khavinson's 2023 paper argues, or in something else in the complex, is asserted rather than demonstrated.
  • The COVID-19 comparative study does not state group sizes in its abstract, and its English and Russian abstracts report different mortality figures for the Thymalin arm (20.6 percent versus 16.2 percent) and for tocilizumab (28.4 versus 28.8). I could not resolve which is correct.
  • The direction of effect is genuinely ambiguous: the cell-culture work shows anti-inflammatory TNF and IL-6 suppression while the clinical framing is immune stimulation. Both cannot be the whole story.
  • No dose-ranging study exists. The 10 mg per day figure is inherited from Soviet-era practice.
  • Autoimmune risk is mechanistically plausible and completely uncharacterised - there is no cohort large enough to have detected it.
  • Cost figures are indicative grey-market estimates and were not verified against live vendor listings in this session.

Papers