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ThymalinSmall moleculeNo amino acid sequence. Icon reflects category theme only.Also known as: Timalin, Thymaline, THYMALIN®
A 4.1-fold mortality reduction over six to eight years. That's the headline number from Khavinson's geroprotective trials in elderly patients given biannual courses of Thymalin plus Epithalamin, a bovine thymic peptide extract containing the active dipeptides EW (L-Glu-L-Trp) and KE. The catch: all published data comes from a single Russian research group, with zero independent Western replication. Still, over 40 years of clinical use and 293 PubMed-indexed publications make Thymalin one of the most studied bioregulators in the longevity space. Adults over 60 seeking immune restoration use it in short 10-day courses, twice yearly.
Four amino acids changed the survival curve. In Khavinson's 6 to 8 year follow-up of elderly patients (n approximately 100)[1], biannual courses of Thymalin plus Epithalamin reduced mortality by 4.1 times compared to controls. Thymalin (also written as Timalin) is a peptide complex isolated from calf thymus gland, first registered in Russia in 1982 under Samson-Med (reg. cert. LS-000267). Its primary bioactive component, the dipeptide L-Glu-L-Trp, was later synthesized as the standalone drug Thymogen. The mechanism is epigenetic rather than pharmacological in the traditional sense. Short peptides (EW, KE, EDP) bind to double-stranded DNA and histone proteins, triggering gene expression changes in thymic progenitor cells. T-cell precursor differentiation accelerates; CD28 expression increased roughly 6.8 times in one published study (PMC7686446). The biological effect persists for months after a single 10-day course. Real-world use centers on adults over 60 with measurable immunosenescence. A 2021 randomized controlled trial in 80 elderly COVID-19 patients (PMC8654498) found 10 mg intramuscular daily for 10 days cut hospital mortality roughly in half (19.4% vs 40.9%). All of this originates from one research group at the St. Petersburg Institute of Bioregulation and Gerontology. No independent Western trial has attempted to replicate the findings. The data is promising and internally consistent, but the single-source limitation is real.
Thymalin works at the gene expression level rather than through classical receptor binding. Its short dipeptides, primarily L-Glu-L-Trp (EW) and L-Lys-L-Glu (KE), interact directly with double-stranded DNA and histone proteins. This triggers epigenetic changes in thymic progenitor cell populations within 24 to 48 hours of the first dose. The downstream effects cascade through multiple immune pathways. T-cell precursor differentiation accelerates from bone marrow-derived progenitors into mature T-lymphocytes. CD4/CD8 ratios normalize toward the healthy adult range of 1.5 to 2.5. Natural killer cell cytotoxicity increases measurably. Intracellular cyclic nucleotide levels shift, modulating immune cell signaling. Neutrophil chemotaxis and phagocytosis both improve. Cytokine regulation is part of the picture too. Thymalin modulates IL-2 and interferon production to restore balanced immune responses rather than simply driving stimulation in one direction. This distinguishes it from single-target immunostimulants; the effect is restorative rather than purely activating. The biological timeline matters. Because the peptide's action is epigenetic, its effects outlast plasma clearance by weeks to months. The half-life of the peptide complex itself is estimated at 2 to 4 hours. The gene expression changes it initiates persist through cell division cycles. This is why 10 days of dosing produces months of measurable immune improvement, and why continuous dosing adds nothing once the epigenetic program is running.
Short-course IM dosing (5–10 mg/day × 10 days, biannual) restores T-cell counts, CD4/CD8 ratios, and NK activity in elderly and immunocompromised patients. Long-term geroprotective data shows 4.1× mortality reduction (Khavinson, n=~100, 6–8 yr follow-up). COVID-19 RCT: 10 mg × 10 days reduced hospital mortality ~50% in elderly patients (19.4% vs 40.9%). All data originates from one Russian research group with no independent replication.
PMC8654498 (2021 COVID-19 RCT, n=80) + PMID 14523363 (6–8 yr mortality, n=~100)
Single research group (Khavinson Institute). No independent Western RCT. All studies elderly population. No formal PK characterization.
Widely trusted for immune restoration and longevity. Valued for short course requirement and clean safety record. Low enthusiasm for subjective effects: benefits are lab-measurable, not acutely felt.
Clinical protocols (5–10 mg × 10 days, biannual) and community protocols are nearly identical. Community added SC as a route option not sanctioned by the Russian label. Dose range, cycling pattern, and goals are consistent.
| Level | Dose / Injection | Frequency |
|---|---|---|
| Beginner | 5mg | Daily |
| Moderate | 10mg | Daily |
| Aggressive | 20mg | Daily |
Standard protocol: 5 to 10 mg intramuscular or subcutaneous, once daily for 10 days. Repeat every 6 months if you're over 60, or every 12 months if younger. Reconstitution math for a 10 mg vial: add 1 mL bacteriostatic water. Each 0.1 mL (10 units on a U-100 insulin syringe) then equals 1 mg. For the beginner 5 mg dose, draw 50 units. For the standard 10 mg dose, you'll use the entire vial in one shot at 100 units; that means one vial per day for a 10-day course (10 vials total). The thing most beginners miss: you won't feel anything. Thymalin's benefits are lab-measurable, not subjectively perceptible. Get a CBC with differential and CD4/CD8 ratio before your course and again 4 to 6 weeks after. That's how you confirm it's working. The Russian label specifies intramuscular only. Community widely uses subcutaneous without issue, but no published bioavailability comparison exists for the extract form. If you want to match the clinical evidence exactly, go IM in the gluteal or deltoid.
Bioregulator protocol: 5-10 day course repeated every 6 months. Effects persist well beyond the treatment window. Some protocols call for annual courses in younger adults and biannual courses in those over 60.
Thymalin acts through epigenetic regulation: its short dipeptides (EW, KE) trigger lasting changes in gene expression in thymic progenitor and T-lymphocyte populations. The biological effect outlasts plasma presence by weeks. Continuous daily dosing adds no incremental benefit once gene expression changes are initiated and may interfere with consolidation during the maturation window. The 6-month off period allows full expression of the stimulated immune program before the next course. This is the foundational principle of all Khavinson bioregulators.
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Expected: Improved T-cell counts and CD4/CD8 ratio within 2–4 weeks post-course. Reduced infection frequency over the following 6-month window.
Monitor: CBC with differential and CD4/CD8 ratio at baseline and 4–6 weeks post-course.
Gather supplies: Thymalin 10 mg lyophilized vial, bacteriostatic water, a mixing syringe (25G 1 inch), and an injection syringe (27G or 29G, 0.5 inch for SC or 1 inch for IM). Alcohol swabs for vial tops and injection site.
Reconstitute by adding 1 mL (100 units) of bacteriostatic water to the vial. Aim the stream against the glass wall, not directly onto the powder. Swirl gently until dissolved. Do not shake.
At 1 mL per 10 mg vial: 50 units on a U-100 insulin syringe equals 5 mg (beginner). 100 units equals 10 mg (standard). For 20 mg, you'll need two vials.
For intramuscular (label-approved route): gluteal or deltoid, 1 inch needle, slow steady push. For subcutaneous (community route): abdomen or thigh, pinch skin, 45-degree angle.
Rotate injection sites each day across the 10-day course.
After reconstitution, store the vial at 2 to 8 degrees C (refrigerator). Use within 10 days. Lyophilized powder stores at room temperature for up to 6 months or refrigerated for up to 3 years.
Do not extend beyond 10 days; the epigenetic effects continue developing after you stop.
Standard doses apply: 5–10 mg per injection
Russian label explicitly states IM route. IV explicitly prohibited per Russian prescribing information. Gluteal or deltoid site preferred.
Community uses same doses (5–10 mg); no published bioavailability comparison to IM for the extract form
Russian label does not sanction SC for Thymalin. Widely used by community for convenience. No published bioavailability or efficacy equivalence data for SC route with the bovine extract form. Cannot confirm equivalent clinical outcome.
Khavinson flagship longevity stack. Thymalin addresses immunosenescence (thymus); Epitalon addresses pineal aging and telomerase activation. The combination produced 4.1× mortality reduction in the 6–8 yr Khavinson study.
10 mg Thymalin + 5–10 mg Epitalon daily × 10 days, biannual
Complementary immune targets. Thymalin acts upstream at thymic progenitor/stem cell level; TA1 acts downstream on mature immune cells via TLR signaling. Sequential (Thymalin course → TA1 maintenance) is the logical use pattern.
Community-only pairing for combined immune restoration and tissue repair; no formal combination study.
Thymalin directly counteracts immunosuppression. In transplant recipients this risks organ rejection. Explicitly listed in Russian prescribing information as a contraindicated combination.
Do not combineHigh-dose steroid protocols blunt Thymalin's immunostimulatory mechanism, reducing or eliminating efficacy.
Pricing updated 2026-04-09
The most important safety concern with Thymalin isn't a side effect from the peptide itself. It's the risk of using it when you shouldn't. In anyone with an active autoimmune condition (rheumatoid arthritis, lupus, Hashimoto's thyroiditis, multiple sclerosis), Thymalin's broad T-cell stimulation can worsen flares. The Russian clinical literature studied healthy elderly patients and post-surgical recovery cases. Not established autoimmune disease. Organ transplant recipients on immunosuppressants face a specific danger. Thymalin directly counteracts tacrolimus, cyclosporine, and mycophenolate. Using it risks organ rejection. This combination is explicitly listed in Russian prescribing information as contraindicated. For people without autoimmune conditions or transplant history, the safety profile is remarkably clean. Across decades of clinical use and published studies, serious adverse events are absent from the literature. Injection site soreness is the most common complaint; it's mild and resolves on its own. Rare low-grade fever has been reported in a small number of patients, typically during the first few days of a course. One community-reported issue deserves attention. Some users stacking Thymalin with Epitalon concurrently have reported restlessness or akathisia. This isn't documented in clinical studies, but the reports are consistent enough to note. Separating the two courses by 1 to 2 weeks resolves it. Sourcing adds a layer of risk that traditional side effect profiles don't capture. Authentic Thymalin is a complex bovine extract containing multiple short peptides. US-synthesized products labeled "Thymalin" may contain only a single synthetic peptide. No published comparative analysis of US versus Russian product equivalence exists. Request a certificate of analysis confirming L-Glu-L-Trp content from any US supplier. Pregnancy and breastfeeding are absolute contraindications. Known hypersensitivity to bovine-derived products or thymic peptides is another. Stop immediately and consult a physician if you develop signs of allergic reaction, unexpected immune activation, or symptoms suggesting autoimmune flare.
Verify Thymalin dosing and safety with a second opinion
Authentic Thymalin is a natural bovine thymic extract (not a single synthetic peptide). The original Samson-Med THYMALIN® (registered Russia 1982, reg. cert. LS-000267) contains a complex mixture of short peptides (EW, KE, EDP). US-synthesized "Thymalin" products may be single synthetic peptides that differ in composition and efficacy from the original extract. No published comparative analysis of US vs. Russian product equivalence exists.
| Test | When | Target |
|---|---|---|
| CBC with differential | Baseline before course; 4–6 weeks post-course | Lymphocyte count increase; normalization of pre-course lymphopenia if present |
| CD4/CD8 T-cell ratio | Baseline; 4–6 weeks post-course | Normal adult range 1.5–2.5; improvement from depressed baseline expected |
| NK cell activity | Optional: baseline and 4–8 weeks post-course | — |
| CRP and IL-6 | If course is for acute immune recovery; baseline and post-course | — |
Quantifies lymphocyte counts and overall immune cell populations; primary measure of Thymalin response in clinical studies
Direct marker of T-cell differentiation response; used as primary endpoint in Khavinson clinical studies
Thymalin specifically enhances NK cell cytotoxicity in clinical studies; measurable via NK cytotoxicity assay
Khavinson COVID-19 studies showed faster normalization of inflammatory markers with Thymalin vs. standard care
Treatment initiation. No noticeable changes yet. Peptide begins modulating gene expression in immune cells and thymic tissue.
Early immune markers begin shifting. Some patients report improved energy or reduced frequency of minor symptoms. T-cell precursor differentiation accelerates.
Course completion. Measurable improvements in T-cell counts and CD4/CD8 ratios in clinical studies. NK cell activity increases.
Immune improvements continue to develop after the course ends. Reduced incidence of acute respiratory infections observed in clinical cohorts. Immune markers stabilize at improved levels.
Sustained immune benefits from a single course. Khavinson studies showed reduced infection rates and improved survival persisting for 6+ months. Next course typically administered at the 6-month mark.
Days 1 through 3, Course Initiation: The dipeptides EW and KE start binding to DNA and histone proteins almost immediately. Epigenetic changes in thymic progenitor cell gene expression begin within 24 to 48 hours. You won't notice anything. Some users report slight fatigue or a mild energy shift around day 2 or 3. Injection site soreness is possible; rare low-grade fever has been reported. Days 4 through 10, Active Course: T-cell precursor differentiation picks up speed. CD28 expression increases roughly 6.8 times based on published data (PMC7686446). NK cell activity starts climbing. Most people still report zero perceptible change, which is normal. A minority notice improved energy or fewer minor symptoms. Injection site reactions may continue; no systemic adverse effects have been documented in clinical studies. Weeks 2 through 4 Post-Course, Immune Consolidation: This is when labs start telling the story. T-cell counts and CD4/CD8 ratios show measurable improvement in clinical study data. NK cell activity peaks. The biological effect outlasts the peptide's plasma presence by weeks. Some users note fewer minor infections. There's still no acute subjective "feel" to this peptide. Months 2 through 6, Sustained Benefit Window: Khavinson's studies showed reduced infection rates and improved immune markers persisting for a full 6 months after a single 10-day course. The mortality reduction data (4.1 times) came from biannual courses sustained over 6 to 8 years. Community consensus aligns: fewer colds, faster recovery from illness. The value proposition is lab numbers and longevity rationale, not day-to-day perceptible changes. Next course is typically scheduled at the 6-month mark for adults over 60.
Dipeptides (EW, KE) bind to DNA/histone proteins; epigenetic changes in thymic progenitor cell gene expression begin within 24–48 hours.
No noticeable changes. Some users report slight fatigue or a mild energy shift on days 2–3.
T-cell precursor differentiation accelerates; CD28 expression increases ~6.8× (PMC7686446). NK cell activity begins rising.
Majority report no perceptible change. A minority note improved energy or slight reduction in minor symptoms.
T-cell counts and CD4/CD8 ratio measurably improved in clinical studies. NK activity peaks. Biological effect outlasts peptide plasma presence by weeks.
Labs begin showing improvement. Some users note reduced incidence of minor infections. No acute subjective "feel."
Khavinson studies show reduced infection rates and improved immune markers persisting for 6 months post-single-course. Mortality reduction data based on biannual courses over 6–8 years.
Community consensus: fewer colds, faster recovery from illness. Valued primarily for labs and longevity rationale rather than acute subjective experience.
Source: Estimated from dipeptide/short peptide pharmacokinetics; no formal PK study published for Thymalin complex
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Thymalin is classified as a research chemical in the United States. It does not have FDA approval for any indication. It cannot be legally marketed as a drug or dietary supplement for human use in the US. In Russia, Thymalin has been a registered pharmaceutical since 1982 (Samson-Med, registration certificate LS-000267). It is prescribed clinically for immune restoration in elderly patients, post-surgical immune recovery, and as a geroprotective agent. The drug is available over the counter in some Eastern European countries. For US-based purchasers, Thymalin is available through research peptide suppliers as a lyophilized powder sold "for research purposes only." Authentic Samson-Med product can also be sourced through EU pharmacies that ship internationally. WADA status is not specifically listed, but athletes subject to anti-doping testing should verify with their governing body before use. This content is for educational and informational purposes only. It does not constitute medical advice. Consult a qualified healthcare provider before using any peptide. Peptide Schedule does not sell peptides or endorse specific suppliers.
Peptide Schedule Research TeamReviewed Apr 20268 Citations
