Thymulin

Facteur Thymique Serique (FTS), Serum Thymic Factor, Zinc-Thymulin

Checked Oct 28, 2026

The short answer

No human evidence yet for immune support and anti-aging in healthy adults (injected)

Grade D for immune support and anti-aging in healthy adults: no human trial has tested it for those uses.

Approved?: Not approved for any use.
Safety: C, thinly characterized: The human trials reported minimal or no significant side effects, but none was in healthy adults, the abstracts give little detail, and there is no long-term safety data.

The full answer: what it is for, the dose, the units

What people take it for: People take injected thymulin for immune support and anti-aging, and a topical form for hair loss. The human trials that exist are of a synthetic version, in rheumatoid arthritis and multiple sclerosis.

Does it work for immune support and anti-aging in healthy adults (injected)? D, no human evidence yet. Result: not tested in humans.

Grade D for immune support and anti-aging in healthy adults: no human trial has tested it for those uses. For rheumatoid arthritis the synthetic form is grade A, with two placebo-controlled trials that worked; in multiple sclerosis one trial found no benefit.

No approval for any use.

Highest evidence for any use: A for rheumatoid arthritis, synthetic thymulin (nonathymulin), two randomized placebo-controlled trials.

Safety: C, thinly characterized. The human trials reported minimal or no significant side effects, but none was in healthy adults, the abstracts give little detail, and there is no long-term safety data.

Do not use if: No established contraindications. Theoretical caution in active autoimmune disease, organ transplant recipients on immunosuppression, or active malignancy given T-cell stimulatory activity.

Could it be placebo? Two placebo-controlled trials of the synthetic form beat placebo in rheumatoid arthritis (56% v 17% improved) and one did not in multiple sclerosis, but for immune support or anti-aging in healthy adults there is no controlled trial, so a placebo effect cannot be ruled out.

The dose people use, and the units to draw

No verified dose statement found for how people use it. The rheumatoid arthritis trials tested 1, 5 and 10 mg per day of the synthetic form and 5 mg did best; the cycles quoted online have no named non-seller source, so none is printed here.

Source	Dose	How often and how	Who it was for	Link
Amor et al. 1987, Ann Rheum Dis (two randomized, double-blind, placebo-controlled trials of nonathymulin, a synthetic thymic peptide hormone)	1, 5 or 10 mg per day (5 mg did best)	Daily; route, duration and patient numbers are not stated in the abstract	People with rheumatoid arthritis	Abstract: 5 mg gave global improvement in 56% v 17% on placebo (p less than 0.02)
Nonathymulin multiple sclerosis trial, Acta Neurol Scand 1989 (randomized, double-blind, placebo-controlled pilot)	Dose not stated in the abstract	Subcutaneous for 6 months, followed 6 more months	40 matched patients with evolving multiple sclerosis and moderate disability	Abstract: no difference in disability scores; authors conclude not effective
Synthetic serum thymic factor (FTS) immunology study, 1983	10 mcg/kg	Intravenous every 3 days	4 cancer patients (an NK-cell immunology experiment, not a treatment trial)	Abstract, in vivo paragraph
Huberman Lab with Dr. Abud Bakri, Peptides: The Science, Uses & Safety (June 1, 2026)	No thymulin dose stated	Discusses thymulin as a zinc-dependent nine amino acid peptide with a very short half-life; the only thymic peptide dose given is for thymosin alpha-1	General audience	Chapter 01:38:13; transcript text read, no thymulin dose found

The online cycle and the zinc co-dose previously on the site had no named non-seller source and are removed. Huberman Lab with Dr. Abud Bakri discusses thymulin without a dose. No Examine or Attia page on thymulin turned up. The Vickers 2017 topical alopecia paper could not be opened, so no concentration is cited. The rheumatoid arthritis abstract does not state route, duration or patient numbers.

Reported by the named source, never prescribed by us.

How many units do I draw?

Use the calculator: units on the syringe equal the dose in mg divided by the mg per mL of your mixed vial, times 100 for a U-100 syringe. Open the dose calculator

Why it might work

Zinc binding activates the peptide
Thymulin is a 9-amino-acid nonapeptide
Thymocyte receptor binding and T-cell differentiation
The active zinc-thymulin complex binds
Spinal microglial suppression and p38 MAPK inhibition
In rodent pain models
Hair follicle anagen phase prolongation (hypothesized)
In hair follicle biology

Assumed pathway, not shown in people.

ASSUMED (established in animals, not confirmed in humans): Thymulin binds specific receptors on immature thymocytes and peripheral T-cells, driving differentiation of T-cell subsets and enhancing NK cell activity. Zinc is required for correct receptor-binding conformation. In the CNS, thymulin appears to modulate microglial activation and suppress pro-inflammatory cytokine production via p38 MAPK pathway inhibition. In hair follicles, thymulin is hypothesized to prolong the anagen (growth) phase by acting on follicular immune privilege. The zinc-thymulin complex declines with age as the thymus involutes, which may contribute to immune senescence.

The trials, claim by claim

Rheumatoid arthritis and multiple sclerosis claims describe nonathymulin, a synthetic version of the thymic hormone (serum thymic factor); the abstracts do not state route or patient numbers for the arthritis trials.

Used for immune support, hair loss, and anti-aging, with real animal data on T-cell maturation and anti-inflammatory pain relief via p38 MAPK.
Human trials are old and limited to the synthetic form: two placebo-controlled rheumatoid arthritis trials (positive, 1987) and one multiple sclerosis trial (negative, 1989). The only hair data is an unblinded, 18-person topical study in a journal flagged as a potential predatory publisher.
The catch: zinc alone probably accounts for a meaningful chunk of reported immune benefits, and nobody has run the trials needed to separate thymulin from the correction of ordinary zinc deficiency.

Synthetic thymulin (nonathymulin) improved rheumatoid arthritis in two randomized, placebo-controlled trials.

Result: worked

Amor 1987 reports two randomized, double-blind, placebo-controlled trials of nonathymulin, a synthetic thymic peptide hormone (serum thymic factor, the zinc-bound nonapeptide). Three schedules of 1, 5 and 10 mg per day were compared; 5 mg did best, with global improvement in 56% versus 17% on placebo (p less than 0.02) and gains on four objective measures. Adverse effects were minimal and immune lab markers did not clearly change. Limits: 1987, one research group, no replication found, and the abstract does not state the route, duration or number of patients.

PubMed: Amor B et al. Nonathymulin in rheumatoid arthritis: two double blind, placebo controlled trials. Ann Rheum Dis 1987 (PMID 3310925)

Synthetic thymulin (nonathymulin) did not help multiple sclerosis in a randomized, placebo-controlled pilot.

Result: did not work

A randomized, double-blind, placebo-controlled trial gave subcutaneous nonathymulin (synthetic serum thymic factor) or placebo to 40 matched patients with evolving multiple sclerosis and moderate disability for 6 months, with 6 more months of follow-up. Disability scores, ambulation index and functional scale did not differ between groups and no significant side effects were recorded. The authors concluded it is not effective in this group.

PubMed: Nonathymulin treatment of multiple sclerosis: double-blind pilot study. Acta Neurol Scand 1989 (PMID 2618585)

Thymulin reduces inflammatory cytokines and attenuates inflammatory pain

Result: not tested in humans

Multiple rat and mouse studies show thymulin reduces hyperalgesia and pro-inflammatory cytokines (TNF-a, IL-1b, IL-6) via p38 MAPK inhibition and spinal microglia suppression. No human pain trials.

PubMed: Thymulin treatment attenuates inflammatory pain by modulating spinal cellular and molecular signaling pathways (PMID 30851702)

Topical zinc-thymulin promotes hair growth in androgenetic alopecia

One open-label uncontrolled study (n=18, 17 male, 1 female, ages 35-90) found significant hair assessment improvement after 6+ months of topical spray. No placebo arm, no blinding. Published in Hair Therapy and Transplantation 2017. NOTE: OMICS Group, which the journal's publisher is associated with, appears on Beall's list of potential predatory publishers and was ordered by a federal court in March 2019 to pay $50.1 million over deceptive publishing practices. The Vickers study should be read with this context in mind and not treated as equivalent to peer review in a reputable journal.

Longdom/Hair Therapy (Beall's-listed publisher): Vickers et al. 2017 - Zinc-Thymulin Alopecia. Publisher credibility concerns noted above.

Thymulin activity declines with aging and can be partially restored by zinc supplementation

Result: worked

The cited paper (PMID 8582786) is a review of mouse thymic explants in which zinc addition restored the zinc-bound form of thymulin. In people, two small randomized trials of zinc raised the blood activity of thymulin: 27 Crohn's disease patients in remission on 200 mg/day zinc sulfate for 3 months (60 mg/day did not; PMID 8364132) and a pilot in very old adults given zinc-fortified milk for 2 months (PMID 24771015). The endpoint in both is a thymulin activity assay, a surrogate, not infections or other health outcomes.

Thymulin supports T-cell differentiation and immune reconstitution

Result: mixed

Strong mechanistic and animal data. Thymulin drives thymocyte maturation and T-cell subset function. Human data are three immunodeficient children given synthetic serum thymic factor intravenously (PMID 6124716, case reports) and four cancer patients (PMID 6195118, NK activity rose in two and fell in two). The rheumatoid arthritis trial found no clear immunological changes (PMID 3310925). No randomized trial shows thymulin improving T-cell outcomes.

PMC: Thymus-Neuroendocrine Axis review (PMC2688715)

A synthetic thymulin-related analogue peptide (PAT) has analgesic potency comparable to NSAIDs in animal pain models

Result: not tested in humans

Rat studies with PAT, a synthetic analogue of thymulin (not native thymulin itself), show dose-dependent reduction of mechanical and thermal hyperalgesia comparable to steroidal and non-steroidal drugs. This evidence is for an analogue compound, not for native thymulin directly. Species translation to humans is completely untested for either compound.

PubMed: Potent analgesic and anti-inflammatory actions of a novel thymulin-related peptide (PAT, a synthetic analogue, not native thymulin) in rats (PMID 12110619)

In aged mice, thymulin suppressed inflammatory myeloid cell activity through NF-kB, enhanced antitumor T-cell immunity and sensitized tumors to anti-PD-L1 therapy.

Result: not tested in humans

Heterochronic parabiosis, bone-marrow chimeras and a breast tumor model in mice; human data limited to blood cell frequencies. No thymulin was given to people.

Kanemaru et al., Nat Commun 2026 (PMID 42481458)

Risks and the label warnings

Adverse events

No serious adverse events are reported in the human studies we found: the rheumatoid arthritis trials reported minimal adverse effects (PMID 3310925), the multiple sclerosis trial no significant side effects (PMID 2618585), and the topical study (n=18) no systemic effects or local irritation over 4-10 months. That study was published in a journal from a publisher on Beall's list of potential predatory publishers, which limits confidence in the peer review quality of this safety finding. Subcutaneous use was studied in one 40-patient multiple sclerosis trial; there is no controlled safety data in healthy adults.

Contraindications

No established contraindications. Theoretical caution in active autoimmune disease, organ transplant recipients on immunosuppression, or active malignancy given T-cell stimulatory activity.

Theoretical concerns

Immune modulation carries theoretical risk of tipping autoimmune balance in susceptible individuals. Zinc co-dosing at high levels (above 40 mg/day chronically) risks copper depletion independently of thymulin.

What nobody knows yet

Long-term effects of exogenous thymulin in adults with a functional (non-involuted) thymus are completely unknown. No pharmacokinetic data for subcutaneous dosing in humans. No data on interaction with TRT, GLP-1 agonists, or other peptide protocols.

What else could explain the result

Users who report immune improvements are often simultaneously correcting zinc deficiency (which alone improves thymulin activity), running peptide stacks (BPC-157, TB-500, Thymosin alpha-1), or on TRT (which has independent immune-modulatory effects). Hair growth users frequently combine with minoxidil or finasteride. Attribution is nearly impossible.

Is the vial what it says?

Cross-checked against the cited sources below. The compound grade reflects the two rheumatoid arthritis trials of the synthetic form; the immune-support and anti-aging uses have no human trial. The analgesic evidence (PMID 12110619) concerns a thymulin analogue (PAT), not native thymulin. The Vickers 2017 citation comes from a publisher on Beall's list of predatory publishers (associated with OMICS Group, which a federal court ordered in March 2019 to pay $50.1 million over deceptive publishing practices), and is flagged as such.

Half-life and storage

Half-life: Not established in humans. Peptide is a 9-amino acid nonapeptide likely subject to rapid enzymatic degradation in serum. Animal models suggest lymphoid tissue targeting within 90 minutes of subcutaneous injection but half-life numbers are not published for human pharmacokinetics.

Once mixed: Unknown. Lyophilized thymulin is assumed to require refrigeration and bacteriostatic water reconstitution consistent with other research peptides, but stability data specific to thymulin is not published. Zinc-complexed form may have different stability than the free peptide.

What I noticed, and what people report

What people report

Volume of reports: faint. Little real-world record, or mostly noise.

Low. Thymulin appears in peptide forums and clinic blogs but generates far less community discussion than BPC-157, TB-500, or Thymosin alpha-1. Confounded heavily with Thymalin (a different crude thymic extract product widely used in Russian longevity protocols).

Inconsistent. Immune and energy reports mixed. Hair users report slow partial improvement. Many who report benefits are stacking with zinc correction, minoxidil, or TRT making isolation impossible.

Low. Community reports are overwhelmingly anecdotal with no separation from confounders. Clinic testimonials are not independent evidence.

Anecdote: Some users on injectable thymulin 20-day protocols report reduced frequency of minor illness over the following months, though baseline health, zinc status, and concurrent stack make attribution speculative.
Anecdote: Topical zinc-thymulin users targeting hair loss report very slow partial improvement (5-6 months before visible change), with high dropout before the 6-month threshold where the Vickers study showed effects.
Anecdote: A subset of longevity-protocol users pair thymulin with Thymosin alpha-1 and report synergistic immune improvement. No separation of effects is possible.
Anecdote: Energy and mood uplift reported by some users is almost certainly confounded by zinc repletion (a common deficiency) rather than thymulin-specific activity.

Reports are anecdote, not proof.

Can you tell if it is working?

Not trackable

No objective way to confirm thymulin is working, routine labs and every consumer/wearable modality miss its immune effect.

Bloodwork

No blood proxy

Nothing on a routine panel confirms this one. Anyone who says otherwise is guessing.

Thymulin (FTS-Zn) is a zinc-dependent thymic peptide whose action is inducing intrathymic T-cell differentiation. Any blood signal would therefore be a small rise in circulating T-lymphocyte populations, but only from a genuinely lymphopenic/immunosenescent baseline where thymic output is the rate-limiting step. In an immunocompetent adult that effect is buried in normal CBC variation, is abolished entirely in zinc-deficient patients, and cannot be attributed to thymulin rather than to infection, cortisol, CMV status, or regression to the mean. There is no routine blood proxy that tracks thymulin efficacy.

Read this before you spend on labs

Routine bloodwork cannot confirm thymulin efficacy. No human study has shown thymulin alone shifting any lab, and the writeup itself concedes zero verified human biomarker changes. The candidate markers are real and orderable but were removed on audit: absolute lymphocyte count and the lymphocyte-to-monocyte ratio are non-specific CBC indices moved far more by infection, stress, cortisol, corticosteroids, and diurnal timing than by thymulin; CD4:CD8 by flow cytometry is a specialty order (not a wellness lab) that is dominated by CMV status and infection. All three are mechanistic hope, not validated efficacy readouts, and any drift is interpretable only as a trend from a depressed baseline and is indistinguishable from regression to the mean. The effect is a subtle, thymic-dependent immunomodulation with no attributable blood signature, treat it as unmeasurable in routine labs.

Bottom line

Thymulin has essentially no verifiable efficacy readout outside a research immunology lab. Blood is graded 'none', absolute lymphocyte count, lymphocyte-to-monocyte ratio, and CD4:CD8 are dominated by infection, stress, diurnal variation, and CMV serostatus, not by thymulin. No non-blood modality applies: it is not a metabolic, body-composition, cardiorespiratory, or sleep/autonomic-active compound, so DEXA, CGM, VO2max, sleep/wearable, urine, stool, genetic, and body-composition all measure the wrong thing. The human trials that exist are of a synthetic form in rheumatoid arthritis and multiple sclerosis, plus one uncontrolled topical alopecia study, and local hair regrowth is not a validated systemic-efficacy proxy, and its other claimed effects (immune restoration, anti-inflammatory pain relief) are subjective or measurable only with research-only assays. Track subjective response and infection frequency if you use it, but understand that no accessible objective test can prove it is working.

Logging baseline vs retest is the whole game. The Truth Tracker is our free log for bloodwork, DEXA, genetics, and wearable data, bring your own numbers.

How to track it

History

First documented human use: Randomized trials of synthetic thymulin (nonathymulin) in rheumatoid arthritis (1987) and multiple sclerosis (1989).

1977Bach and Dardenne at Institut Necker (Paris) isolate and sequence Facteur Thymique Serique (FTS) from porcine and human serum. Amino acid sequence confirmed as a 9-residue peptide requiring equimolar zinc for biological activity.
1980sSurge of interest in thymulin and other thymic peptides for autoimmune disease, cancer, and immunodeficiency. Most clinical work used crude thymic extracts (Thymalin) rather than pure thymulin. Interest waned as results were inconsistent.
2000s-2010sRenewed animal research establishes thymulin as a neuroendocrine mediator with analgesic and anti-inflammatory properties beyond immune function. Thymulin-related synthetic analogues explored as pain targets (USPTO patent 7309690).
2017Vickers et al. publish a small open-label topical study in 18 alopecia patients showing hair density improvements with no adverse events. Published in a journal from a Beall's-listed publisher (see claim note on publisher credibility).
Jul 2026Nature Communications reports thymulin falls with age and, in aged mice, suppresses inflammatory myeloid cells and improves response to anti-PD-L1 therapy. Mouse data, no human trial.

All sources

PMC: The Thymus-Neuroendocrine Axis (PMC2688715) - Comprehensive review of thymulin biology(Best single academic source. Covers mechanism, neuroendocrine interactions, and therapeutic potential. Published Annals of the New York Academy of Sciences 2009.)
PubMed: Thymulin prevents pro-inflammatory cytokines in mice (PMID 18991101)(Animal anti-inflammatory data. Representative of the rodent evidence base that most marketed claims rest on.)
Longdom Open Access (Beall's-listed publisher): Vickers et al. Zinc-Thymulin androgenetic alopecia 2017(The only topical human data we found. Small, unblinded, no placebo arm. Published in a journal from a publisher associated with OMICS Group, which appears on Beall's list of potential predatory publishers and was ordered by a federal court in March 2019 to pay $50.1 million over deceptive publishing practices. Do not overweight. Do not treat as equivalent to peer review in a reputable journal.)
Kanemaru et al., Nat Commun 2026, thymulin restrains age-associated myeloid inflammation (PMID 42481458)(Newest primary paper. Mouse parabiosis, bone-marrow chimera and breast tumor-model data plus human blood cell frequencies; no administration to people.)
PubMed: Age-related thymic involution and zinc-thymulin (PMID 8582786)(Solid mechanistic basis for why zinc repletion improves thymulin activity in aging. Does not validate exogenous thymulin injection.)
Amor B, Dougados M, Mery C, Dardenne M, Bach JF. Nonathymulin in rheumatoid arthritis: two double blind, placebo controlled trials. Ann Rheum Dis 1987;46:549-54. PMID 3310925(dose table)
Nonathymulin treatment of multiple sclerosis: double-blind pilot study. Acta Neurol Scand 1989. PMID 2618585(dose table)
Effect of a synthetic thymic factor (facteur thymique serique) on natural killer cell activity in humans. 1983. PMID 6195118(dose table)
Huberman Lab, Dr. Abud Bakri, Peptides: The Science, Uses & Safety, chapter 01:38:13 Thymic Peptide Doses, Thymulin, Zinc (transcript on episode page is untimed)(dose table)

Not medical advice. Grades reflect the evidence as of the date above and will change as data arrives. Reports from users are anecdote, not proof. Talk to a licensed clinician before you act on anything here.