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Thymalin (thymus peptide bioregulator)
A polypeptide complex extracted from the thymus, registered as an immunomodulator medicine in Russia and several CIS countries — so unlike grey-market peptides it has real (if mostly Russian-language and low-quality) human studies. Thymalin is promoted to 'normalize' immune function by stimulating T-lymphocyte differentiation, with claimed uses in respiratory infections, COVID-19 adjuvant therapy, and even longevity. The headline evidence is striking but weak: an open-label Russian cohort reported a 2-fold drop in mortality in elderly people treated with thymalin (± a pineal peptide) over 6-8 years, and unblinded COVID-19 series reported lower hospital mortality when added to standard care. Almost none of this is double-blind, placebo-controlled, or replicated outside Russia/CIS; sample sizes are small; mechanism work is largely in-vitro. Western regulators have NOT approved it. Treat the longevity and mortality claims with strong skepticism.
Prescription medication — not a dietary supplement
Thymalin is a prescription (or investigational) drug, not a supplement. It is included here for reference because people research and discuss it (often used off-label) — not as a recommendation. Take it only under a qualified clinician's supervision and only as prescribed; do not source it from grey-market vendors, where identity, purity, and dosing are unverified. The evidence below reflects its clinical trials.
What the evidence says
Most Thymalin studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from mixed-quality randomised trials published 2003–2023.
Based on 6 studies · 1 RCT
Confidence
Low confidenceBy outcome
A registered Russian/CIS immunomodulator with a plausible mechanism and some human reports, but its evidence is small, unblinded, single-center and unreplicated, so it scores Emerging.
Thymalin is a polypeptide complex isolated from animal thymus tissue, developed by the St. Petersburg Institute of Bioregulation and Gerontology (the Khavinson group) and registered as an immunomodulatory medicine in Russia and several CIS states.
Its proposed action is immunoregulatory: it increases the functional activity and differentiation of T lymphocytes and is reported to normalize CD4/CD8 balance, and its 'active substances' have been characterized as the short peptides/dipeptides KE (Lys-Glu) and EW (Glu-Trp).
Because it is a registered drug in its home jurisdictions, thymalin has a genuine — if methodologically weak and largely Russian-language — clinical literature, which separates it from pure research peptides that have no human data at all.
The most provocative claim is geroprotective: a long-term observational study by Khavinson and Morozov reported that elderly patients treated with thymalin (often combined with the pineal peptide epithalamin) over 6-8 years showed normalized cardiovascular/endocrine/immune indices, fewer acute respiratory and cardiovascular events, and a roughly 2-fold reduction in mortality versus controls, with even larger reductions in those treated repeatedly.
This is a remarkable result on paper, but it is open-label, non-randomized, single-group, decades old, and has not been independently replicated outside the originating institutes — so it cannot be taken as established.
During the COVID-19 pandemic, the same research network reported unblinded clinical series in which adding thymalin to standard therapy in middle-aged and elderly severe-COVID patients lowered hospital mortality (e.g. ~20% vs ~41% with standard care in one comparison) and improved coagulation/lymphocyte indices and the decline of IL-6, CRP and D-dimer; mechanistic work attributes this to KE/EW dipeptides reducing IL-1β/IL-6/TNF-α release in vitro and to stimulation of hematopoietic stem-cell differentiation into mature CD28+ T lymphocytes.
Animal studies (e.g. bone-marrow precursor and thymic-serum-factor work in aged mice) support an immunorestorative effect, and a rat mandible study found thymalin stimulated local immune and reparative responses.
The honest assessment: thymalin is a real, registered immunomodulator with a plausible mechanism and a non-trivial body of human reports — but the evidence is dominated by small, unblinded, single-center, often Russian-language studies from a closely connected group, with little placebo control, scant Western replication, and headline longevity claims that vastly outrun the rigor of the underlying trials.
It is NOT an FDA-approved drug or a dietary supplement; its long-term safety outside the studied contexts is not well characterized; and the dramatic mortality/longevity figures should be read as hypothesis-generating, not proven.
Thymalin is a thymus-derived polypeptide complex reported to increase the functional activity and differentiation of T lymphocytes. In-vitro work suggests it stimulates hematopoietic stem cells toward mature CD28+ T cells and normalizes T-cell subsets — framed as restoring, not over-driving, immune function.
The active substances are characterized as short peptides KE (Lys-Glu) and EW (Glu-Trp). In-vitro, these are proposed to modulate gene expression and reduce pro-inflammatory cytokine release (IL-1β, IL-6, TNF-α), with EW also reported to interact with the ACE2 axis — but this is mechanistic/in-vitro, not clinical proof.
In LPS-stimulated human PBMCs, thymalin and its dipeptides reduced IL-1β/IL-6/TNF-α by 1.4-6-fold; unblinded COVID-19 series reported faster declines in IL-6, CRP and D-dimer. The proposed route from immunoregulation to reduced hyperinflammation — supported mostly by in-vitro and open-label data.
How Thymalin works — from molecular targets to health outcomes. Click an edge to see supporting research.This visualization is in beta — pathways are being refined and expanded.
Avoid — safety in pregnancy and lactation is not established.
Only under specialist supervision — thymalin modulates T-cell balance and its net effect in a given condition is unpredictable.
Avoid unregulated sources — identity, purity and sterility are not guaranteed; a registered pharmaceutical product under clinical care is the only defensible route.
As an immunoregulatory agent, thymalin could theoretically interact with immunosuppressants or other immunomodulators (in COVID series it was compared against tocilizumab). Combined use is not well studied and should be clinician-supervised.
COVID-19 reports describe thymalin altering coagulation markers (fibrinogen, D-dimer). Any concurrent use with anticoagulants should be clinician-monitored, though direct interaction data are lacking.
Tip: Administer per clinical protocol; thymalin is reported to be generally well tolerated in its studied uses.
Tip: Stop and seek care if an allergic reaction occurs.
Tip: Long-term safety outside studied contexts is poorly characterized; do not self-administer chronically.
The current evidence for Thymalin is insufficient to assign an evidence score, based on 6 indexed studies. A polypeptide complex extracted from the thymus, registered as an immunomodulator medicine in Russia and several CIS countries — so unlike grey-market peptides it has real (if mostly Russian-language and low-quality) human studies. Thymalin is promoted to 'normalize' immune function by stimulating T-lymphocyte differentiation, with claimed uses in respiratory infections, COVID-19 adjuvant therapy, and even longevity. The headline evidence is striking but weak: an open-label Russian cohort reported a 2-fold drop in mortality in elderly people treated with thymalin (± a pineal peptide) over 6-8 years, and unblinded COVID-19 series reported lower hospital mortality when added to standard care. Almost none of this is double-blind, placebo-controlled, or replicated outside Russia/CIS; sample sizes are small; mechanism work is largely in-vitro. Western regulators have NOT approved it. Treat the longevity and mortality claims with strong skepticism. Representative study: PMID 36169363.
The commonly studied dose of Thymalin is Thymalin is a registered prescription immunomodulator in Russia/CIS, NOT a dietary supplement — this library does not provide a self-administration protocol. Where it is a registered drug, it is given as an intramuscular injection (typically 10 mg/day for a short course of several days), but any use must be directed by a clinician in a jurisdiction where it is approved.. Individual needs vary — start at the lower end of the range and adjust based on how you respond.
Timing is flexible for Thymalin — consistent daily use matters more than the time of day. Thymalin is injected intramuscularly and dosed as a short course; timing follows the clinical protocol rather than food or circadian considerations.
Thymalin should be used with caution — talk to a healthcare provider before taking it. The most commonly reported side effects are injection-related reactions, hypersensitivity to thymus-derived material, unknown long-term effects. Use caution if any of these apply to you: Not an FDA-approved drug or a regulated dietary supplement — registered as a prescription immunomodulator only in Russia/CIS; use only under a clinician; Known hypersensitivity to thymus-derived peptide preparations; Pregnancy and breastfeeding (not established as safe).
Vitamin A
Mixed evidenceFat-soluble vitamin that maintains night vision, drives immune cell differentiation, and regulates skin turnover and cellular growth.
Selenium
Likely helpsRequired for selenoprotein production that regulates thyroid hormones, powers glutathione peroxidase, and strengthens immune defense.
Multivitamin
Probably helpsNutritional insurance that fills micronutrient gaps. In the large COSMOS trial, a daily multivitamin improved memory and slowed cognitive decline in older adults — but it did not reduce total cancer, cardiovascular disease, or mortality.
Quercetin
Likely helpsFlavonoid with senolytic and anti-inflammatory properties — supports immune defense, allergy relief, and exercise performance.
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Reviewed by Dr. Baher Al Hakim · Last reviewed June 2026 · evidence from 6 studies · how we score · editorial policy
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.
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