--- title: "Thymalin" canonical_url: https://bestpeptidecalculator.app/library/thymalin description: "Thymus-derived polypeptide preparation used in some countries as an immunomodulator. Not FDA-approved; composition is an extract, not a single sequence." updated: 2026-11-07 publisher: Peptide Library notice: "Research and educational use only. Not medical advice." --- # Thymalin Thymalin (also called Thymic extract peptide or Thymalinum) is a thymic polypeptide extract. Thymalin is a preparation of low-molecular-weight peptides extracted from calf thymus rather than a single defined molecule, which is the central fact for interpreting it: no specific sequence, receptor or signalling pathway can be assigned, and batch composition is not standardised as a single-entity drug would be. Thymus-derived polypeptide preparation used in some countries as an immunomodulator. Not FDA-approved; composition is an extract, not a single sequence. Also known as: Thymic extract peptide, Thymalinum. Categories: Experimental. ## Classification - Type: Thymic polypeptide extract / research - Mechanism class: Thymic Peptide - Development stage: Research only - Regulatory class: Research compound, not FDA-approved ## Mechanism Thymalin is a preparation of low-molecular-weight peptides extracted from calf thymus rather than a single defined molecule, which is the central fact for interpreting it: no specific sequence, receptor or signalling pathway can be assigned, and batch composition is not standardised as a single-entity drug would be. It is described as restoring T-cell differentiation in a manner analogous to endogenous thymic hormones, with reported effects on lymphocyte subsets in ageing and immunodeficient states. It is used clinically in several post-Soviet countries. The supporting evidence is regional and largely uncontrolled, and it is not a monographed active ingredient in the United States. Targets: T-cell maturation (proposed). Origin: Bovine thymic polypeptide preparation. ## Properties - Molecular formula: Peptide mixture (2–10 kDa fraction) - Molecular weight: Mixture - Half-life: Not established (polypeptide complex) ## Evidence - Evidence level: Limited Human Evidence - Highest documented: Controlled human trials - Human trials: 2 - Controlled human trials: 1 - Preclinical sources: 0 - Latest source: 2003 No human dose is established for this compound. Each step shows whether the sources Peptide Library has reviewed include that kind of research. Counts are reviewed sources, not every study ever published. Reviews and programme summaries that describe human use are shown as "reported", not as trials, and registered trials without published results are listed but not counted. A higher step means research has progressed further; it does not mean a compound works better or is safer. Compounds whose evidence has not been reviewed yet show "Not reviewed" instead of a guess. ### Studies 1. Peptides of pineal gland and thymus prolong human life. Neuro Endocrinol Lett. 2003. 2003. Controlled human trial. Population: Elderly and older adults (n=266, including epithalamin and combined groups). The authors report lower respiratory illness and mortality than controls [Source](https://pubmed.ncbi.nlm.nih.gov/14523363/) 2. [Effectiveness of administration of thymalin in the complex treatment of pulmonary tuberculosis]. Probl Tuberk. 1990. 1990. Human study (early or uncontrolled). Population: Patients with pulmonary tuberculosis. Not available in the indexed record (Russian-language article) [Source](https://pubmed.ncbi.nlm.nih.gov/2080155/) ## Safety Side effects: Allergic reactions to animal protein. Risks: Extract variability. Human safety basis: Limited human reports Key limitations: No established human dosage.; Not approved by the FDA for any use.. ## Regulatory status Thymalin is not an FDA-approved product. It is sold for laboratory research and has no approved medical use. - FDA status: Not Approved - Availability: Research-Only ## Frequently asked questions ### What is Thymalin? Thymus-derived polypeptide preparation used in some countries as an immunomodulator. Not FDA-approved; composition is an extract, not a single sequence. ### How does Thymalin work? Thymalin is a preparation of low-molecular-weight peptides extracted from calf thymus rather than a single defined molecule, which is the central fact for interpreting it: no specific sequence, receptor or signalling pathway can be assigned, and batch composition is not standardised as a single-entity drug would be. It is described as restoring T-cell differentiation in a manner analogous to endogenous thymic hormones, with reported effects on lymphocyte subsets in ageing and immunodeficient states. ### Is Thymalin FDA approved? No. Thymalin is not approved by the FDA for any indication and is categorised as research-only. It has not been reviewed for safety or efficacy as a medicine, and published research should be read as investigation rather than established use. ### What is the half-life of Thymalin? Reported half-life for Thymalin is Not established (polypeptide complex). Half-life describes how long the compound persists in circulation, not how long any effect lasts, and published figures vary with route of administration, formulation and the population studied. ### What peptides are similar to Thymalin? Compounds most often compared with Thymalin include Thymosin Alpha-1, Thymogen (Oglufanide), Thymopentin and Thymulin. They are grouped by shared mechanism or research area rather than by equivalence, and their regulatory status and evidence base differ. ## References - [\[Use of thymic peptide thymalin in the complex treatment of therapy-resistant schizophrenia\] — Zh Nevropatol Psikhiatr Im S S Korsakova, 1990](https://pubmed.ncbi.nlm.nih.gov/2163147/) - [Expression features of T-lymphocytes, B-lymphocytes and macrophages in the post-traumatic regenerate of the mandible rats under conditions of filling a bone defect with hydroxyapatite-containing osteotropic material and thymalin injecting the surrounding soft tissues — Pol Merkur Lekarski, 2024](https://pubmed.ncbi.nlm.nih.gov/38642352/) - [Reparative osteogenesis in mandible in cases of filling a bone defect with hydroxyapatite-containing osteotropic material and injecting the surrounding soft tissues with thymalin: experimental and morphological study — Wiad Lek, 2024](https://pubmed.ncbi.nlm.nih.gov/38431810/) - [The Influence of KE and EW Dipeptides in the Composition of the Thymalin Drug on Gene Expression and Protein Synthesis Involved in the Pathogenesis of COVID-19 — Int J Mol Sci, 2023](https://pubmed.ncbi.nlm.nih.gov/37686182/) - [\[Geroprotective effect of thymalin and epithalamin\] — Adv Gerontol, 2002](https://pubmed.ncbi.nlm.nih.gov/12577695/)