Thymalin vs Thymulin: Which Is Better for Immunity? BioHarmony head-to-head comparison
Head-to-Head Comparison

Thymalin vs Thymulin: Which Is Better for Immunity?

Should I use thymalin or thymulin?

Reviewed 09/08/2026

Thymulin scores 6.6, thymalin 5.9, and they are not interchangeable. Thymulin is a defined zinc-dependent peptide with receptor-level science, stronger inflammation data and a much cheaper course. Thymalin is an undefined calf-thymus extract whose headline elderly mortality result has never been replicated outside the group that produced it. Cost separates them further.

  • Thymulin 6.6, thymalin 5.9. The 0.7 gap is really an evidence-quality gap, not a size-of-effect gap.
  • Thymulin is one defined nine-amino-acid molecule with mapped receptors. Thymalin is a mixture of thymus peptides of varying length, so you cannot know what is in the vial.
  • Thymalin owns the only human longevity claim here, a 2 to 4 fold elderly mortality drop (Khavinson 2003), and it is single-source and unreplicated. That is why this page carries low confidence.
  • Thymulin is inactive without zinc. It binds zinc one to one, so checking zinc status is not optional, and correcting a deficiency has cleaner human evidence than injecting the peptide.
  • Cost is not close. A thymalin course estimates at $113 to $590 for the month it runs. Thymulin estimates at $22 to $65.
  • Both converge on T-cell differentiation, so running them together is redundant. Both are contraindicated in active or suspected cancer, pregnancy and lactation.

At a Glance

Thymalin
Option A

Thymalin

5.9 / 10 Worth trying
Upside
  • Efficacy 3.8
  • Breadth 3.4
  • Evidence 3.6
  • Speed 3.2
  • Durability 2.7
  • Bioindividuality 3.2
Downside
  • Safety Risk 2.4
  • Side Effects 2.3
  • Cost 2.8
  • Effort 3.2
  • Opportunity Cost 3.0
  • Dependency 2.3
  • Reversibility 1.8
Best at:
  • Immune Function 4.2
  • Longevity 4.0
  • Geriatric 2.6
  • Anti Inflammatory 2.5

Undefined calf-thymus peptide extract from the Khavinson bioregulator program. BioHarmony 5.9, worth trying.

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Thymulin (Zinc-Thymulin)
Option B

Thymulin (Zinc-Thymulin)

6.6 / 10 Worth trying
Upside
  • Efficacy 3.4
  • Breadth 3.6
  • Evidence 3.6
  • Speed 3.0
  • Durability 2.3
  • Bioindividuality 3.6
Downside
  • Safety Risk 1.6
  • Side Effects 1.7
  • Cost 2.8
  • Effort 2.9
  • Opportunity Cost 2.6
  • Dependency 1.8
  • Reversibility 1.6
Best at:
  • Immune Function 4.8
  • Anti Inflammatory 4.0
  • Geriatric 2.6
  • Chronic Pain 2.4

Defined zinc-dependent thymic nonapeptide, also called FTS. BioHarmony 6.6, worth trying.

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Head-to-Head Verdict

Use CaseWinnerRationale
Immune FunctionThymulin (Zinc-Thymulin)Thymulin 4.8 against thymalin 4.2, and the reason is resolution rather than size. Thymulin's action maps to saturable high-affinity receptors near 3 nanomolar on T cells, absent on B and null cells (Pleau 1980). Thymalin's immune case traces to one research lineage, headlined by a stem-cell culture study raising CD28 about 6.8 fold (Khavinson 2020).
Anti InflammatoryThymulin (Zinc-Thymulin)Thymulin 4.0 against thymalin 2.5, the second-widest gap on the page. Thymulin blocked LPS-induced IL-1beta and NF-kappaB nuclear translocation in an alveolar model (Haddad 2009) and matched a synthetic inhibitor in LPS-challenged mice (Novoselova 2014). Thymalin has one adjunct COVID study reporting faster decline in IL-6, CRP and D-dimer (Khavinson 2021).
LongevityThymalinThymalin 4.0 against thymulin 2.3, the widest gap in the matrix, and it is won by a single study. Khavinson 2003 reported mortality falling roughly 2 to 4 fold over 6 years in a 266-person elderly cohort, unreproduced in over twenty years. Thymulin has no lifespan outcome at all, only thymic plasticity in old animals (Mocchegiani 2006).
GeriatricTieDead even at 2.6 each, and for opposite reasons. The Khavinson program targets the immunosenescent older adult, but its data is single-source and non-blinded. Thymulin's older-adult case rests on a zinc-driven deficit that adding zinc restores (Fabris 1984), a biomarker finding rather than a clinical outcome.
HealthspanTieThymalin 2.4 against thymulin 2.3, a gap of 0.1 that means nothing. Thymalin's healthspan claim rides on the same elderly cohort that claimed fewer cardiovascular, endocrine and respiratory problems without isolating any of them. Thymulin's rests on biomarker normalization (Fabris 1984) with no human study measuring a healthspan outcome for the injected peptide.
HormonalTieCall this even and notice the subratings do not: thymulin 2.4 against thymalin 1.6. Thymulin's number comes from stimulating pituitary prolactin and TSH release in an age-related way (Brown 1998), which reads as a caution as readily as a benefit. Thymalin has no controlled hormonal endpoint. Neither is something to take for a hormonal reason.
Recovery RepairThymalinThymalin 2.2 against thymulin 1.8, and this is a weak win on a thin base. Thymalin injection altered T-lymphocyte, B-lymphocyte and macrophage expression in a rat mandible regenerate (Boiko 2024). Thymulin has no recovery or repair endpoint at all, human or animal, so any benefit there is inferred from anti-inflammatory mechanism. Neither belongs in a training recovery stack.
Wound HealingTieEven, at thymalin 1.9 against thymulin 1.6. Thymalin's number borrows from the same rat bone-regeneration model that carries its recovery score, and thymulin has no wound-healing data in people at all. A 0.3 subrating gap built out of one animal study on one side and nothing on the other is not a reason to pick either.
EnergyTieEven, at thymalin 1.9 against thymulin 1.7, and both numbers are anecdote. Subjective vitality after a thymalin course is a common community report and is unmeasured in any controlled study. Thymulin has no energy outcome published. If more energy is what you are buying, neither of these is the purchase.

Cost Comparison

InterventionMonthly CostNotes
Thymalin$113 to $590ESTIMATE, priced 2026-09-07 through the research-chemical channel. Gray-market 10 mg vials run about $45 to $59. A 5 to 10 day course at 5 to 10 mg a day is 25 to 100 mg of material, so the month a course runs costs between roughly 2.5 vials and 10 vials.The wide range is the dose range, not price uncertainty. Run the low end of the protocol and it is cheap. Run the high end and it is not. This is a channel estimate, not a measured price.
Thymulin$22 to $65ESTIMATE, priced 2026-09-08 through the research-peptide channel. BioLongevity Labs lists a 10 mg vial at $64.97, and because rational use sits in the low microgram range, one vial covers a multi-month observation course.That works out to about $22 a month spread over three months, or $65 for a single-month course plus supplies. Add the cost of zinc testing, cold storage and sterile injection supplies, which the vial price does not cover. This is a channel estimate, not a measured price.
The differenceThymulin is roughly 5 to 9 times cheaperThe ranges do not overlap. Thymalin's floor of $113 sits above thymulin's ceiling of $65, so on estimated pricing thymulin is the cheaper option at every point in both ranges. Both figures carry the ESTIMATE flag from their source reports.The reason is dose scale. Thymalin is dosed in milligrams by intramuscular injection over a short course. Thymulin is dosed in micrograms, so a single vial lasts. Cost is one of the few places on this page where the two separate cleanly.

When to Switch

These two run on different clocks, and that changes how you judge them. Thymalin is a short course: first noticeable change around day 5, full effect near day 10, and a 2-week assessment window. Thymulin is slower: first noticeable around week 2, full effect near week 6, and a 6-week window.

Both sets of onset figures are estimates rather than measured values, so treat the window as the decision point and ignore how you feel in the first few days.

Move from thymalin to thymulin when you want a defined molecule you can actually verify, when inflammation rather than immune restoration is the target, or when the cost of repeat milligram-dose courses stops making sense.

Before you do, check zinc status, because thymulin is inactive without it and correcting a deficiency has cleaner human evidence than injecting the peptide (Fabris 1984, Prasad 1998). Move the other way, from thymulin to thymalin, only if you are deliberately running the Khavinson bioregulator program and accept that its human case is single-source.

Do not overlap them. Both drive T-cell differentiation through thymic-hormone signaling, so running both stacks injection burden, sourcing risk and cost on top of each other with no second pathway to show for it. Finish one course, reassess at that side's own window, then decide.

Who Should Pick What?

Deliberately running the Khavinson peptide bioregulator program

Thymalin

Thymalin is the immune pillar of that program and nothing else substitutes for it inside that framework. Go in knowing the whole human case is single-source, and judge it on your own response rather than on the headline mortality number.

Chasing the elderly mortality result specifically

Tie

Neither, honestly. Khavinson 2003 is the most eye-catching number in this comparison and the weakest supported: one 266-person cohort, one research group, no independent replication in over twenty years. Thymulin has no lifespan endpoint to offer as an alternative.

Inflammation is the target and you want mapped mechanism

Thymulin (Zinc-Thymulin)

Anti-inflammatory subrating 4.0 against 2.5. Thymulin suppressed IL-1beta and blocked NF-kappaB translocation in an alveolar model (Haddad 2009) and reduced colitis severity in mice (Sun 2007). Those are animal and cell endpoints, not a human trial, so treat it as observation.

Older adult with a documented zinc deficit

Thymulin (Zinc-Thymulin)

Correct the zinc first. Zinc repletion restored serum thymulin activity in experimental human zinc deficiency (Prasad 1998) and four months of oral zinc decreased infections while normalizing thymulin (Licastro 1994). That is the cleanest human evidence anywhere in this comparison, and it does not require injecting anything.

You want a molecule you can actually verify before injecting it

Thymulin (Zinc-Thymulin)

Thymulin is a defined nonapeptide, so a certificate of analysis means something. Thymalin is an undefined extract, which is why batch testing is rarely available at all. If verifiable identity is your bar, only one of these clears it.

Treating chronic pain on your own

Tie

Neither, and thymulin in particular. Its pain effect runs in two directions, hyperalgesic at low doses and analgesic at higher ones (Dardenne 2006), so guessing your way along that curve at home can make pain worse. Thymalin has no pain endpoint at all.

Active or suspected cancer, pregnancy, or lactation

Tie

Neither. All three are listed contraindications on both reports. Deliberately pushing T-cell immunity and neuroendocrine signaling is the wrong direction in an active or suspected cancer setting, and there is no human safety data in pregnancy or breastfeeding for either.

Autoimmune disease, transplant recipient, or on immunosuppressive therapy

Tie

Neither. Thymalin lists autoimmune disease, transplant status and immunosuppressive therapy as contraindications. Thymulin lists autoimmune disease on immunomodulator therapy. Both work by stimulating the arm of the immune system those situations are trying to hold down.

Research Highlights

  1. Mechanism Difference

    Thymalin and thymulin are mechanistically redundant, not complementary. Thymalin is a low-molecular-weight peptide complex extracted from calf thymus, reported to stimulate T-cell immunity and push hematopoietic stem cells toward mature T-lymphocyte differentiation. Its active dipeptides KE and EW have been isolated, but the product itself is a mixture.Thymulin is a single nine-amino-acid hormone that binds zinc one to one to form the active metallopeptide, then drives T-cell differentiation through high-affinity receptors while suppressing IL-1beta and NF-kB signaling. Same destination, one defined route and one undefined one.

  2. Safety Comparison

    Neither peptide carries a documented fatal signal, and both risk profiles are dominated by sourcing rather than pharmacology. Thymalin scores 2.4 on safety risk against thymulin's 1.6, where lower is better, and 2.3 against 1.7 on side effects. It is a bovine biological bought gray market, so sterility, endotoxin and bovine-protein allergy are the real exposures.Thymulin's specific hazard is dose direction: its pain effect is hyperalgesic at low doses and analgesic at higher ones (Dardenne 2006), so self-treating pain by guessing is the practical risk. Both are contraindicated in active or suspected cancer, pregnancy and lactation. Thymulin also reverses faster, scoring 1.6 against 1.8 on reversibility.

  3. Cost Comparison

    The ranges do not overlap. A thymalin course estimates at $113 to $590 for the month it runs, priced 2026-09-07 through the research-chemical channel, because 10 mg vials at about $45 to $59 have to cover 25 to 100 mg of material. Thymulin estimates at $22 to $65, priced 2026-09-08, because low-microgram dosing stretches one $64.97 vial across months.Both figures are channel estimates rather than measured prices, and both carry the ESTIMATE flag from their source reports. The driver is dose scale: milligrams by intramuscular injection against micrograms subcutaneously. Thymulin's number also excludes zinc testing, cold storage and injection supplies.

  4. Evidence Quality

    Both sides score 3.6 on evidence strength, and the identical number hides two different problems. Thymalin has human data, including a 266-person elderly cohort (Khavinson 2003) and a severe-COVID mortality comparison (Kuznik 2022), but every study traces to one Russian program with no Western replication in four decades.Thymulin has the deeper basic science, from its 1977 isolation (Dardenne 1977) through receptor mapping (Pleau 1980) to zinc-binding chemistry (Dardenne 1994), and no modern human trial of the injected peptide at all. Its cleanest human signal comes from zinc-supplementation studies where thymulin was the measured marker (Fabris 1984), not the treatment.

  5. Editorial Verdict

    Thymulin scores 6.6 and thymalin 5.9, and the 0.7 gap understates how differently these two behave. Take thymulin if you want a defined molecule with mapped receptors, the better inflammation data, a course that estimates at a fraction of the price, and a certificate of analysis that actually means something. Check zinc status first, because the peptide is inactive without it.Take thymalin only if you are deliberately testing the Khavinson bioregulator program and accept that its entire human case, including the 2 to 4 fold elderly mortality claim, comes from one group and has never been reproduced. Neither is a proven therapy. This page carries low confidence because thymalin's own report does.

Frequently Asked Questions

Is thymalin the same thing as thymulin?
No, and the names are the only thing they share. Thymulin is a single zinc-dependent nine-amino-acid hormone that circulates in serum and was isolated in 1977 (Dardenne 1977). Thymalin is a mixture of calf-thymus peptides of varying length, produced by mild acid extraction (Morozov 1997). One is a molecule, the other is an extract.
Which one has better evidence, thymalin or thymulin?
Both score 3.6 on evidence strength, with different weaknesses. Thymalin has human data, but all of it traces to one Russian program with no Western replication. Thymulin has the deeper basic science and no modern human trial of the injected peptide, and its cleanest human signal comes from zinc studies where thymulin was measured rather than given (Fabris 1984).
Which is cheaper?
Thymulin, by a wide margin. A thymalin course estimates at $113 to $590 for the month it runs, because 10 mg vials at $45 to $59 have to cover 25 to 100 mg of material. Thymulin estimates at $22 to $65 because low-microgram dosing stretches a single $64.97 vial across months. Both are channel estimates, not measured prices.
Do I need to check my zinc level before using thymulin?
Yes. Thymulin binds zinc one to one and the unbound peptide is inactive (Dardenne 1994), so zinc status decides how much active hormone you have. In a documented deficiency, correcting zinc is the better-evidenced move on its own: zinc repletion restored serum thymulin activity in experimental human deficiency (Prasad 1998).
How long before I know if either one is working?
Different clocks. Thymalin is a short course with first noticeable change around day 5, full effect near day 10 and a 2-week assessment window. Thymulin is slower: first noticeable around week 2, full effect near week 6 and a 6-week window. Every one of those figures is an estimate rather than a measured value, so judge at the window.
Can I use thymalin and thymulin together?
There is no good reason to. Both push T-cell differentiation through thymic-hormone signaling, so the mechanisms are redundant rather than additive, and stacking them doubles injection burden, sourcing risk and cost with no second pathway behind it. Finish one course, reassess at that side's own window, then decide.
Is the elderly mortality result for thymalin real?
It is published and it is striking: mortality roughly 2 to 4 fold lower over 6 years in a 266-person elderly cohort (Khavinson 2003). It is also single-source. No independent group has reproduced it in over twenty years, and it comes from the same program that produced the compound. Treat it as an unconfirmed claim, not a result you can bank on.
Who should not use either of these?
Anyone with active or suspected cancer, anyone pregnant or breastfeeding, and anyone with autoimmune disease, since both work by stimulating the immune arm those conditions are trying to hold down.Thymalin adds transplant recipients, people on immunosuppressive therapy and anyone with a bovine-protein allergy. Thymulin adds unknown zinc status and self-treating chronic pain, because its dose-response runs in two directions.

Evidence Sources

Glossary

Quick reference for the medical and technical terms used in this comparison.

FTS Facteur Thymique Serique
The original French name for thymulin, the serum thymic factor. Also written as zinc-thymulin or ZnFTS when the active zinc-bound form is meant.
KE and EW Lys-Glu and Glu-Trp
The two active dipeptides isolated from thymalin. They are sold as separate products, which are different compounds rather than thymalin itself.
NF-kB Nuclear Factor kappa B
A master switch for inflammatory gene expression. Thymulin blocks its movement into the cell nucleus, which is the core of its anti-inflammatory case.
IL-1beta Interleukin 1 beta
A front-line inflammatory cytokine. Thymulin suppresses it selectively in the models where it has been tested.
CD28 Cluster of Differentiation 28
A surface marker of mature T cells. Thymalin raised it about 6.8 fold in human stem-cell culture, which is its main mechanistic evidence.
CD4/CD8 Helper to Cytotoxic T-Cell Ratio
A standard readout of immune balance. Normalizing it is the endpoint both of these peptides are sold against.
HSC Hematopoietic Stem Cell
The bone-marrow precursor that becomes every blood and immune cell. Thymalin is reported to push these toward mature T-lymphocytes.
COA Certificate of Analysis
A batch-level identity and purity test. It is meaningful for a defined molecule like thymulin and rarely obtainable for an undefined extract like thymalin.
ARDS Acute Respiratory Distress Syndrome
Severe inflammatory lung failure. One of the respiratory indications claimed for thymalin in the Russian literature.
Nick Urban

Health Optimization Researcher & CHEK Holistic Lifestyle Coach Level 2

Neither report carries a personal rating or review, so this comparison is driven by the live BioHarmony scoring data on both reports and the published evidence they cite

Reviewed Sep 8, 2026 · next review Dec 7, 2026

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