ImmuneТималинThymus polypeptide extract

Thymalin

Thymus-gland polypeptide EXTRACT (a mixture, not one molecule) · Khavinson/Morozov immunomodulator

Thymalin is the flagship 'peptide bioregulator' of the Soviet/Russian gerontology school founded by Vladimir Khavinson and Vladimir Morozov — and the single most important thing to understand about it is that it is not a molecule. It is an extract: a complex of low-molecular-weight polypeptides pulled out of calf or cattle thymus glands and freeze-dried, much like how brain-derived mixtures such as Cerebrolysin are made. That means it has no single chemical formula, no one molecular weight, and no single amino-acid sequence — a point worth stressing because chemical databases will hand you a tidy formula for the name 'Thymalin' that actually belongs to a completely different peptide (thymulin), a misattribution that should be ignored. What's genuinely real about Thymalin is the program behind it: a decades-long Soviet and Russian clinical-immunology effort, a large Russian-language literature, and a sizeable PubMed footprint (nearly 300 records), including recent mechanistic work attributing activity to short dipeptides (Lys-Glu and Glu-Trp) found within the extract. What's thin is independent verification. The most eye-catching claim — a landmark geroprotector trial reporting two- to four-fold lower mortality in elderly people given Thymalin over six to eight years — comes from the originators' own group, was largely open-label by modern standards, and has never been independently replicated in the West. There is no FDA approval. The fair framing: a real, historically significant Russian immunomodulator extract with a striking but single-source, largely unreplicated efficacy record — and an identity that must be described as a tissue-derived mixture, never as a defined small molecule.

The short version

The first thing to get right about Thymalin is that it is not a single substance — it is an extract. It's made by taking thymus glands from calves or cattle, pulling out a mixture of small proteins (polypeptides) with acid, and freeze-drying the result. So 'Thymalin' is really a name for a batch of mixed thymic peptides, the same way a soup is named for its ingredients rather than for one molecule. This is exactly how other organ-derived products, like the brain extract Cerebrolysin, work.

Because it is a mixture, Thymalin has no single chemical formula, no one molecular weight, and no single sequence. This matters in practice: if you look up 'Thymalin' in a chemical database you may get a clean formula and structure back, but that record actually belongs to a different peptide called thymulin — a name collision, not the real thing. Any product page that assigns Thymalin a single molecular structure is getting it wrong.

What is real is the history. Thymalin came out of a serious, decades-long Soviet and then Russian research program in clinical immunology, led by Vladimir Khavinson and Vladimir Morozov, and it has been used in Russia as an immune-modulating injection in settings like cancer support, infections, surgery and burns. There's a large Russian-language literature and even recent papers pointing to two small dipeptides inside the extract as the active pieces. The honest limitation is that the most dramatic claims — including a long-term study reporting that elderly people given Thymalin had two to four times lower mortality — come from the originators' own group, weren't run to modern blinded-trial standards, and have never been reproduced by independent Western researchers. It's a historically important, genuinely-used extract with a striking but unconfirmed track record.

Molecular identity

Specs

Molecular formula: Not applicable (mixture)

Composition: Standardized complex of low-molecular-weight polypeptides extracted from calf/cattle thymus gland (a mixture, not one molecule)NCBI MeSH C032805; PMID 37686182
Defined single molecule?: No — it is an extract / mixture with no single structureNCBI MeSH C017757 ('unknown MF')
Molecular weight: Not applicable (mixture of low-MW polypeptides)NCBI MeSH C032805
Characterized constituents: Short dipeptides incl. KE (Lys-Glu) and EW (Glu-Trp) identified as bioactive componentsPMID 37686182 (Int J Mol Sci 2023)
CAS (preparation): 79621-14-0 (NCBI MeSH registry; refers to a compound of unknown MF)NCBI MeSH UID 67032805
Misattribution warning: The name 'Thymalin' wrongly resolves in PubChem to CID 3085284 — that record is Thymulin/Nonathymulin (C33H54N12O15, MW 858.9, pGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn), a DIFFERENT defined molecule. Do not treat as Thymalin's formula.PubChem CID 3085284 (verified)
Molecular target: No single defined receptor; proposed thymic-hormone-like restoration of T-cell differentiation and immune balance (originator-school claim, not independently established)PMID 37686182; Russian clinical literature (CITED)
Half-life: Not established (no published pharmacokinetics; it is a multi-component extract, not a single molecule)Not established
Origin / developer: V.G. Morozov & V.Kh. Khavinson (USSR Military Medical Academy; St. Petersburg Institute of Bioregulation and Gerontology)PMID 14523363
Regulatory status: Registered & used in USSR/Russia (IM immunomodulator); NOT FDA-approved; Western grey-market 'research chemical' onlyRussian clinical literature (CITED); absence of FDA record

Plain English

Mechanism

The classic rationale for Thymalin is 'thymic hormone replacement.' The thymus is the organ where T-lymphocytes (a core part of the immune system) mature, and its function declines with age. Thymalin, as a thymus-derived peptide mixture, is claimed to restore T-cell differentiation, rebalance T-helper and T-suppressor populations, and normalize both cellular and humoral immunity. This is a plausible framing, but it rests largely on the originators' own body of work rather than on an independent Western mechanistic consensus.

More recent work from the same lineage tries to pin the activity on specific small peptides within the extract. A 2023 study attributes effects to two dipeptides found in Thymalin — KE (Lys-Glu) and EW (Glu-Trp) — proposing that they influence gene expression and protein synthesis, and modelling their relevance to immune-related gene pathways. Other recent papers claim Thymalin activates differentiation of human hematopoietic (blood-forming) stem cells and modulates inflammation and proliferation in monocyte/macrophage cell lines.

The status of all this should be stated plainly: the mechanism is biologically plausible and there is recent in-vitro and modelling work, but there is no independent Western mechanistic consensus, and the strongest mechanistic claims come from the program that created the compound. The dipeptide-component hypothesis is interesting precisely because it would tie a messy extract to defined molecules — but it remains a hypothesis from one school.

Sources:PMID 37686182 PMID 33237528

Why people reach for it

Potential benefits

Thymalin is the flagship thymic immunomodulator of the Soviet/Russian bioregulator school — here is what draws people to it, kept honest about a striking but single-source, largely unreplicated record.

A decades-used thymic immune restorer — Thymalin is the program's headline 'thymic hormone replacement' extract, claimed to restore T-cell differentiation and rebalance immunity in aging — the main reason people reach for it, framed as the originating school's thesis rather than proven outcome.
A genuine clinical history, not just a research chemical — It was registered and used in the USSR/Russia for decades as an immune adjunct in oncology support, infection, surgery, and burns — a real-world track record that sets it apart, even though it sits outside modern Western validation.
The peptide behind the longevity headline — Its most-cited draw is a long-term geroprotector study reporting markedly lower mortality in elderly people — a striking figure people point to, but one from the originators' own open-label work, never independently replicated.
A sizeable literature with a component hypothesis — Unlike a black-box extract, recent work pins activity on two defined dipeptides inside it (Lys-Glu and Glu-Trp) — appealing to people who want at least a mechanistic handle, framed as a single-school hypothesis.
Pairs across immune arms — Because it works at the thymus/T-cell-maturation stage, it slots alongside peptides that act downstream like Thymosin Alpha-1 — a complementary immune-axis pairing rather than the same lever twice.

Sources:PMID 14523363 PMID 37686182 PMID 33237528

What people reach for Thymalin for, drawn from its positioning and the single-school (largely Russian, mostly open-label) research — not proven Western outcomes or medical claims. Its striking efficacy figures are originator-reported and unreplicated, and it is not a treatment for any condition.

Implied timing

Best time to dose

Implied best time

Evening (or consistent)

A gentle evening lean is reasonable for Thymalin, lining the immune signal up with the body's overnight repair window — but a consistent daily time matters more than the exact hour.

Much of the body's immune consolidation and repair runs overnight, so giving a thymic/immune signal in the evening is a sensible habit — read this as reasoned from immune rhythm, not as a Thymalin finding.
Thymalin has no published pharmacokinetics and no half-life on record (it is a multi-component extract, not a single molecule), so there is no clearance curve to time against — consistency day-to-day outweighs the precise hour.
It is an intramuscular injection given as a short defined course; locking the dose to the same daily slot across the course is the practical priority, with evening the gentle preference where it fits.

No study establishes an ideal time of day for Thymalin — the evening lean is reasoned from the overnight immune-repair window and how it's used, not proven. As a rule of thumb most peptide dosing lands in the midday-to-evening window; for Thymalin the soft preference is evening, but any consistent time is defensible.

Sources:PMID 14523363

How to run it

Dosing & protocol

Thymalin is dosed here as an intramuscular injection — the route used in all Russian clinical literature and the only validated form. It is a lyophilized (freeze-dried) extract reconstituted with bacteriostatic water or saline before injection. There is no FDA-approved dose and no Western-validated regimen; the ranges and course structure below come directly from the cited Russian clinical literature. Read them as a map of how Thymalin is actually used — not a Western-sanctioned prescription.

Russian-source clinical convention, never independently replicated in a Western controlled trial: Thymalin has no FDA approval and no Western-validated dose. The originator-reported figures are real data, but from a single research school, largely open-label by modern standards. Every number here is reported usage from that literature — the dosing table below is the evidence backbone.

Dose ranges

Russian clinical convention is a short, defined course — not open-ended daily use.

Clinical course dose:: ~5–10 mg intramuscularly per day for ~5–10 days (the range reported across the Russian clinical literature for immune-adjunct use in oncology support, infectious disease, and post-surgical recovery). Reported usage from cited sources — exact per-product monograph values were not independently verifiable.
Geroprotector course:: Annual repeated courses in the landmark trial — applied during the first 2–3 years of a 6–8-year observation period, with one subgroup receiving Thymalin (plus the pineal peptide epithalamin) annually for 6 years. These schedules were not validated in a modern controlled Western trial.
Frequency:: Course-based, not continuous daily maintenance: a short injection course, then a rest period of weeks to months before the next course — reflecting Russian clinical convention for short-acting thymic immunomodulators.

Administration (intramuscular)

Thymalin is injected intramuscularly after reconstitution — the gluteal muscle (upper outer quadrant), the vastus lateralis (outer thigh), or the deltoid are standard IM sites.

Injection site:: Gluteal muscle (upper outer quadrant) is the most common site in Russian clinical practice for IM immunomodulators of this type. The outer thigh (vastus lateralis) or deltoid can substitute for lower-volume injections. Rotate sites across a multi-day course to avoid local soreness at one spot.
Reconstitution vehicle:: The lyophilized extract is dissolved in bacteriostatic water or isotonic saline (0.9% NaCl) immediately before injection. A small volume — 1–2 mL per dose — is consistent with standard IM injection volume limits for these muscle groups.
Time of day:: No published circadian data for Thymalin — see Best time to dose above. A gentle evening lean is reasonable (aligning the immune signal with the overnight repair window), but during a short course a consistent daily time matters more than the exact hour.

Cycle / course

Thymalin is given in discrete, time-limited courses — the defining structural feature of the Russian bioregulator protocol model.

Standard course:: 5–10 consecutive daily IM injections (~5–10 mg each). Russian immune-adjunct use in clinical settings typically describes 1–2 such courses per year, not continuous use.
Rest between courses:: Rest intervals of several weeks to months separate courses — no back-to-back cycling. The geroprotector studies used annual courses, which is the most data-supported interval.
Historical context — epithalamin co-use:: In the landmark geroprotector trial, the combined arm (Thymalin + epithalamin, a Khavinson-school pineal peptide bioregulator) produced the largest claimed mortality reduction (~4.1× vs control). Their co-administration is cited historical fact — not independently verified evidence for the combination, and not a protocol endorsement.

Reconstitution at a glance

Mixing math for a 10 mg vial; the on-page calculator handles custom vial sizes.

Mixing:: 10 mg vial + 2 mL bacteriostatic water or saline = 5 mg per mL. On a 100-unit (1 mL) insulin syringe: 5 mg = 100 IU (full syringe) · 2.5 mg = 50 IU. A single 1 mL IM draw delivers 5 mg — the midpoint of the cited clinical dose range.
Volume note:: IM injections typically use 1–2 mL per site. Dissolving a 10 mg vial in 2 mL gives two full 1 mL injections at 5 mg each, which fits the standard course dose without awkward partial measures.

Sources:PMID 14523363

Substrate the signal needs

Nutritional cofactor precision

Thymalin's claimed job is to restore thymic function and T-cell immune activity. The useful cofactors are the nutrients that the thymus and T-cells actually run on — zinc anchors the list because it is textbook-essential for thymic hormone activity and T-cell development, a fact of standard immunology that applies regardless of Thymalin's own evidence status.

Reasoned from standard thymic/T-cell immune nutrition applied to Thymalin's claimed mechanism — not a Thymalin cofactor study. Supplement doses are established general ranges, not Thymalin-specific findings. Thymalin's own evidence base is single-school and largely unreplicated; these cofactors are the substrate its effect would require.

Amplify — Zinc + Vitamin D + Selenium

The three nutrients most directly linked to thymic hormone activity and T-cell function.

Zinc (anchor):: 15–30 mg zinc picolinate or bisglycinate daily. Zinc is required for thymic hormone activity (thymulin is a zinc-dependent metallopeptide) and for T-cell differentiation and function — severe zinc deficiency literally shrinks the thymus and blunts T-cell immunity. This is the single most defensible nutritional pairing for anything aimed at the thymus.
Vitamin D:: Dose to blood level — most adults need 2,000–5,000 IU daily to reach the sufficient range (25-OH-D ≥ 30 ng/mL). Vitamin D receptors are present on immune cells and it is a key regulator of both innate and adaptive immune tone — deficiency damps T-cell function, sufficiency supports it.
Selenium:: 100–200 mcg selenomethionine daily. Selenium is essential for selenoprotein-based antioxidant defense in immune cells; inadequate selenium blunts immune-cell activation and proliferation. Keep within range — selenium is toxic at high doses.

Supply — Protein + Vitamin C

Raw materials the immune response and any peptide synthesis consume.

Dietary protein:: ≥ 1.2–1.6 g per kg body weight daily from whole-food sources. Immune cells, antibodies, and thymic peptides are all built from amino acids — insufficient protein directly impairs immune response and limits what any immunomodulatory input can do.
Vitamin C:: 500–1,000 mg daily (split dose, with meals). Vitamin C accumulates in immune cells at concentrations far above plasma levels and supports lymphocyte function and antioxidant defense during immune activation. Not a thymic-specific pairing — general immune substrate.

Mitigate — minimal cost on a short course

Thymalin is a 5–10 day IM course, not a long continuous protocol — no known depletion cost.

No cofactor mitigation needed for the course itself:: Unlike anabolic peptides or GH secretagogues that alter metabolic substrate demand, a short thymic course has no established depletion profile. The only meaningful mitigation is ensuring the copper-to-zinc ratio stays balanced if zinc is supplemented long-term beyond the course window: 2 mg copper bisglycinate per 30–50 mg sustained zinc use.

Combinations + timing

Stacking notes + timing windows

Thymalin targets the thymic/T-cell arm of immunity. The honest stack landscape is narrow: meaningful complementary partners either work on a different immune arm (adaptive vs innate), or are other Khavinson-lineage bioregulators where at least historical co-administration data exists. Stacking two thymic preparations is pushing the same lever twice — redundant, not synergistic.

User combinations reasoned from complementary mechanism or historical originator co-use — none studied head-to-head in a Western trial. Thymalin itself carries single-school, largely unreplicated evidence. Stacking single-school thymic preparations multiplies speculation, not evidence. Doses for partner peptides are community convention; 'reached for' describes where users go, not a proven indication.

Thymalin + Thymosin Alpha-1

Two immune levers — thymic restoration plus adaptive-immune amplification — on different arms of the same system.

Why it works:: Thymosin Alpha-1 is a defined single peptide (28 AA, thymosin fraction 5 origin) that directly enhances T-helper cell activity, NK-cell function, and cytokine signaling — the downstream outputs Thymalin is claimed to support by restoring the thymic environment upstream. Different mechanism level: Thymalin works at the thymus-maturation stage; Thymosin Alpha-1 works at the activated-T-cell signaling stage. Complementary levers, not the same one twice.
The protocol:: Thymalin: ~5–10 mg IM daily for a 5–10 day course. Thymosin Alpha-1: 1.5 mg subcutaneously twice weekly, run on its own schedule alongside or following the Thymalin course. Two separate injection routes (IM vs SC) — they are not co-injected.
Outcome:: Reached for in community use for broad immune-competence goals and chronic-infection contexts. Honesty note: Thymosin Alpha-1's most rigorous standalone Western trial was null; its evidence is also primarily from an originator lineage. Stacking two single-school immune peptides compounds the uncertainty.

Thymalin + Thymogen (Glu-Trp)

Thymogen is the synthetic version of one of Thymalin's own characterized active dipeptides — a defined small molecule where the extract has a mixture.

Why it works:: Thymogen is the synthetic Glu-Trp (EW) dipeptide, one of the two bioactive constituents identified inside Thymalin (per PMID 37686182). The logic: Thymalin delivers the full extract; Thymogen delivers one identified active component in a defined, reproducible dose. Some users run Thymogen between Thymalin courses to maintain the same thymic signaling with a single defined molecule. Same mechanism family — use with awareness that you are pushing the same lever, not adding a complementary one.
The protocol:: Thymalin: ~5–10 mg IM daily ×5–10 days (the course). Thymogen: nasal drops or IM (per its preparation), commonly in the inter-course maintenance window. The combination during an active Thymalin course is likely redundant — the main rationale is for the off-course period.
Outcome:: Reached for when continuity of thymic peptide signaling between Thymalin courses is a goal. Honest caveat: Thymogen shares Thymalin's Khavinson-school evidence base — independent replication is similarly thin.

Thymalin + Epithalamin (Epitalon)

The exact pairing from the landmark geroprotector trial — thymic bioregulator + pineal bioregulator — where the combined arm claimed the largest mortality effect.

Why it works:: Epithalamin (and its synthetic analogue Epitalon) is the Khavinson-school pineal peptide bioregulator, claimed to normalize pineal melatonin output and circadian signaling. The rationale: immune function declines with age in part via thymic involution (Thymalin's target) and in part via disrupted pineal/circadian regulation (Epithalamin's target) — two different upstream causes of age-related immune decline. In the cited trial (PMID 14523363), the combined Thymalin + Epithalamin arm (annually dosed, 6 years) produced a claimed ~4.1× lower mortality versus control — the most dramatic figure in the dataset.
The protocol:: Thymalin: ~5–10 mg IM daily ×5–10 days (standard course). Epitalon: 10 mg IM daily ×10 days (the Khavinson-school course dose), run as a separate or co-timed course. In the trial both were given in repeated annual courses — not simultaneous daily injections of both, but overlapping course windows.
Outcome:: Reached for in community geroprotection and longevity contexts, directly modeled on the landmark trial. Critical honesty: the trial's claimed ~4.1× mortality reduction is an originator-reported figure from a single open-label study, never independently replicated. The pairing is historically documented, not independently validated.

Reconstitution math

Reconstitution calculator

Calculated for a 1 mL U-100 insulin syringe (100 units/mL).

Peptide per vial

BAC water added

Desired dose

Units per dose

Draw to this mark on a U-100 syringe

Volume per dose: 0.2 mL
Doses per vial: 10
Concentration: 5 mg/mL

One vial lasts

Daily: 10 days
Every other day: 20 days
5×/week: 14 days

Research use only. Not for human consumption. Outputs are reference values based on research literature — verify all measurements independently.

From the studies

Side effects from research

Thymalin has a long claimed safety record in Russian clinical use across decades, and the source literature generally presents it as well tolerated as a short-course intramuscular immunomodulator. No major safety signal is highlighted in that literature.

The reassurance is heavily qualified. As an animal-tissue-derived peptide mixture, it carries the general theoretical considerations of biological extracts (immune reactions to foreign protein material, batch variability), and the safety claims come from older, often uncontrolled Russian reports rather than modern, independent pharmacovigilance. Rare or long-term effects would not necessarily have been captured.

Gray-market sourcing of an extract adds substantial purity and identity risk on top of the molecule-level uncertainty. The honest summary: a long history of reported tolerability, but no modern, rigorous, independent safety database — and the extra uncertainty inherent to a tissue-derived mixture.

As reported in literature

Research dosing ranges

These are Russian-source clinical reports for a thymus EXTRACT, shown for reference only — there is no FDA-approved or Western-validated regimen, and the dose figures are reported usage, not registry-confirmed. The striking mortality numbers below come from the originators' own group, are open-label by modern standards, and have never been independently replicated. Read them as claimed, not established.

Dose	Route	Model	Outcome	Sources:
~5–10 mg daily ×5–10 d	IM (reconstituted)	Russian clinical practice — immune adjunct (oncology, infection, surgery, burns) (CITED)	Reported immunomodulation / immune normalization; reported usage from clinical literature, exact per-product mg/day not registry-verified	PMID 14523363
Annual courses ×6 yr	IM	Human geroprotector trial — 266 elderly, 6–8 yr observation (Khavinson & Morozov 2003)	CLAIMED ~2.0–2.1× lower mortality vs control (Thymalin alone), ~1.6–1.8× (epithalamin alone), up to ~4.1× for the combined, annually-dosed subgroup; open-label, single-program, never independently replicated	PMID 14523363
Course-based	IM	Russian oncology use — disseminated cervical cancer combined treatment (Vishnevskaia 1991)	Reported as an immunological adjunct in combined cancer treatment; older Russian-language report, lower-tier evidence	PMID 2014686
In vitro	Cell culture	Hematopoietic stem-cell differentiation (Khavinson 2020)	CLAIMED activation of human hematopoietic stem-cell differentiation; mechanistic in-vitro work from the originating lineage	PMID 33237528

Quick answers

Frequently asked

Is Thymalin a single peptide?

No — this is the key point. Thymalin is an extract: a mixture of low-molecular-weight polypeptides pulled from calf/cattle thymus glands. It has no single chemical formula, molecular weight, or sequence. It's handled like other organ-derived mixtures (e.g., the brain extract Cerebrolysin), described by its source and composition rather than a defined structure.

Why do some databases show a formula for Thymalin?

Because of a name collision. A naive lookup of 'Thymalin' can return PubChem CID 3085284 with formula C₃₃H₅₄N₁₂O₁₅ (MW 858.9) — but that record actually belongs to thymulin (Nonathymulin), a completely different, defined peptide. It's a misattributed synonym and should be ignored for Thymalin.

Are the mortality-reduction claims real?

They come from a real study (Khavinson & Morozov 2003, 266 elderly over 6–8 years) that reported roughly two- to four-fold lower mortality with Thymalin. But it was conducted by the originators' own group, was largely open-label by modern standards, and has never been independently replicated in the West. Report the numbers as claimed by the originators, not as established fact.

Is Thymalin the same as thymulin or thymosin alpha-1?

No. Thymulin and thymosin alpha-1 are each single, structurally-defined peptides. Thymalin is a multi-peptide extract with no single structure. The similar names cause frequent confusion, but they are different things.

Is Thymalin approved or banned in sport?

It is registered and used in Russia but is NOT FDA-approved; in the West it exists only as a grey-market 'research chemical.' Its WADA status wasn't verifiable by name, but as a thymus-derived immunomodulatory peptide preparation it could plausibly fall under WADA's peptide-hormone/growth-factor category or the non-approved-substance catch-all. Treat it as high-risk and check the current WADA list directly.

Primary sources

References

PMID 14523363Khavinson & Morozov, Neuro Endocrinol Lett 2003 — landmark geroprotector trial (266 elderly, 6–8 yr; Thymalin ± epithalamin; claimed mortality reduction)
PMID 37686182Linkova et al., Int J Mol Sci 2023 — KE & EW dipeptides 'in the composition of the Thymalin drug' and gene expression
PMID 33237528Khavinson et al., Bull Exp Biol Med 2020 — Thymalin activates differentiation of human hematopoietic stem cells
PMID 2014686Vishnevskaia et al., Vopr Onkol 1991 — Thymalin in combined treatment of disseminated cervical cancer (Russian-language)
NCBI MeSH C032805NCBI MeSH Supplementary Concept — 'thymalin' (extract; registry compound of unknown molecular formula)

Research use only · Not medical advice · Updated 2026-06-01