the questions, answered from the record
Thymulin: Frequently Asked Questions
Direct answers on identity, the zinc requirement, safety, dosing, and regulatory standing — each drawn from the cited literature, none offered as medical advice.
What is thymulin?
Thymulin is a zinc-dependent thymic nonapeptide hormone with the sequence pyroGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn, produced by thymic epithelial cells and biologically active only when bound to zinc in a 1:1 ratio [1][2]. It was named in 1982 for the zinc-bound active form of serum thymic factor. It is studied as a research peptide and is not approved for human use.
What is thymulin peptide?
Thymulin peptide is the nine-amino-acid thymic hormone formerly called serum thymic factor (FTS) [1]. It is studied as a research peptide and is active only as the zinc-bound form; the zinc-free apopeptide is inactive [2]. Its molecular weight is near 858.86 Da and its CAS number is 63958-90-7.
Is thymulin the same as serum thymic factor (FTS)?
Yes. FTS — facteur thymique sérique — is the original name, and the term "thymulin" was coined for the zinc-bound, biologically active form of the same peptide once the zinc requirement was established [1]. In the literature, FTS, Zn-FTS, and thymulin all refer to the same nonapeptide.
Why does thymulin need zinc to work?
Zinc binding gives thymulin its active three-dimensional conformation; the zinc-free apopeptide is inactive [1][2]. Chelating the zinc abolishes activity in the rosette assay, and adding zinc back restores it, optimally at a 1:1 metal-to-peptide ratio [1]. Zinc is effectively the molecule's on-switch, not an optional cofactor.
What is the amino acid sequence of thymulin?
Thymulin is the linear nonapeptide pyroGlu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn (written <Glu-Ala-Lys-Ser-Gln-Gly-Gly-Ser-Asn), active only when bound to one zinc ion in a 1:1 molar ratio [2]. The zinc-bound form adopts a specific conformation detectable by NMR, which the apopeptide does not.
What does thymulin do in the body?
Endogenously, thymulin drives T-lymphocyte differentiation and acts as a hypophysiotropic peptide within a two-way thymus-neuroendocrine axis [4]. In research models it also shows anti-inflammatory activity, including suppression of NF-kB signalling [6]. These are described findings, not demonstrated human treatments.
Does thymulin boost the immune system?
In research models thymulin promotes T-cell maturation and modulates immune-cell function, and its activity falls with zinc deficiency and with age [3][11]. In vitro it corrected T-cell immaturity in malnourished children's lymphocytes [8]. This is preclinical and ex-vivo evidence, not a demonstrated human immune treatment.
Does thymulin reduce inflammation?
In animal models thymulin lowered pro-inflammatory cytokines and suppressed NF-kB and SAPK/JNK signalling — for example in LPS-treated mice given thymulin before the challenge [6]. These are research findings in study species, not a demonstrated anti-inflammatory therapy for people.
What are the benefits of thymulin?
In study models thymulin has been associated with T-cell differentiation, reduced inflammatory signalling (including NF-kB suppression), and pituitary and neuroendocrine effects [4][6]. Human benefit is not established. These are research findings, not outcomes demonstrated in adequate human trials.
What are the benefits of thymulin peptide?
Research describes immune-modulating, anti-inflammatory, and neuroendocrine effects of the thymulin peptide in animal and in-vitro models [4][6][8]. These are study findings, not established human benefits, and thymulin is not approved for any indication.
Can thymulin help with autoimmune disease?
Thymulin reduced disease severity in rodent autoimmune-neuroinflammation work and, in vitro, normalized abnormal T-cell subset markers on lymphocytes from rheumatoid-arthritis and lupus patients [4][12]. An open FTS-Zn trial in rheumatoid arthritis reported immunological modulation [9]. These are research findings, not a human autoimmune treatment.
How is thymulin different from thymosin alpha-1?
They are distinct molecules. Thymulin is a zinc-dependent nonapeptide; thymosin alpha-1 is a different, longer thymic peptide with its own sequence, mechanism, and literature [1]. Their data do not transfer between them, and consumer sources that treat them as one are mistaken.
Is there a thymulin supplement?
No. Thymulin is not a dietary supplement and there is no recognized thymulin supplement product. It is handled as a research peptide for laboratory use. Note that serum thymulin activity tracks zinc status, but that is a property of the body's own thymulin, not a supplement claim [3].
Is thymulin FDA approved?
No. Thymulin is not approved by the FDA for any indication and is not a dietary supplement; it is handled as a research peptide for laboratory use only. There is no approved human thymulin product of any kind.
Is thymulin legal to buy?
Thymulin is not a US controlled substance, but it is not approved for human use; research suppliers offer it for laboratory research only. It is not a dietary supplement. Athletes should note that peptide hormones and immunomodulators are scrutinized in sport and should consult current WADA guidance.
What are the side effects of thymulin?
There is no characterized human side-effect profile for thymulin. Early human trials used synthetic analogs (nonathymulin), and a topical pilot was preliminary; thymulin is not approved for human use. See thymulin side effects for the full reading of the safety record.
What are the side effects of thymulin peptide?
The thymulin peptide's human safety data are sparse and dated, and there is no rigorous adverse-event profile. A topical zinc-thymulin pilot reported its preparation as well tolerated, but it was small, single-line in its safety reporting, and low-tier. The accurate position is that thymulin peptide side effects are uncharacterized.
Is thymulin safe?
Thymulin's human safety is not established. Most evidence is preclinical, the human data are limited and dated, and it is handled as a research chemical for laboratory use only. Neither "safe" nor "dangerous" is supported; the question is simply unanswered by adequate human study.
Does thymulin help with hair loss?
A single small open-label pilot studied a topical zinc-thymulin spray in androgenetic alopecia, reported as preliminary and well tolerated. Specific regrowth figures were not independently grounded and should be treated as preliminary. See thymulin and hair loss for the full reading.
What is the dosage of thymulin peptide?
There is no established human dosage of thymulin peptide; it is a research peptide. Reported doses are study findings in animal models — for example 50 µg per mouse intraperitoneally, or 10-50 ng per 100 g in chickens — not protocols for people [13][15]. See thymulin dosage in research for the full register.
How is thymulin administered in research?
In published studies, routes include intraperitoneal, subcutaneous, intracerebroventricular, intratracheal (for gene therapy), and direct in-vitro incubation [4][7][13][14]. In humans, only limited and dated work used analogs or FTS-Zn, plus one topical pilot. There is no approved human injectable thymulin product.
Is thymulin taken as an injection?
Most research used parenteral routes — subcutaneous and intraperitoneal — in animals [13][14]. There is no approved human injectable thymulin product; it is handled as a research peptide for laboratory use. This site does not provide administration guidance for people.
Are there reviews or experiences of thymulin?
Public discussion is thin; thymulin is a niche research peptide with limited human study. This site summarizes the published literature rather than user experiences or product reviews. Where a human-facing claim exists — such as the topical hair-loss pilot — it is read as preliminary against its source.