Thymosin Alpha-1
Also known as: Tα1, Ta1, Thymalfasin, Zadaxin
Thymosin Alpha-1 is a naturally occurring 28-amino acid peptide originally isolated from thymic tissue. It is a potent immunomodulator approved in over 35 countries for treating hepatitis B, hepatitis C, and as an immune adjuvant. It enhances both innate and adaptive immunity without causing immune overstimulation.
Thymosin Alpha-1 is a 3,108.3 Da research peptide. Thymosin Alpha-1 is a naturally occurring 28-amino acid peptide originally isolated from thymic tissue. It is a potent immunomodulator approved in over 35 countries for treating hepatitis B, hepatitis C, and as an immune adjuvant. It enhances both innate and adaptive immunity without causing immune overstimulation.
Also called: Tα1, Ta1, Thymalfasin
3,108.3
Molecular Weight
Daltons
3
Strong Evidence
benefits
5
Studies Cited
peer-reviewed
1600-1600
Typical Dose
mcg
Overview
Thymosin Alpha-1 (Tα1) is an endogenous peptide first isolated from thymosin fraction 5, a preparation derived from calf thymus glands, by Allan Goldstein at the George Washington University in the 1970s. The thymus gland is the primary organ responsible for T-cell maturation and immune system education, and Thymosin Alpha-1 is one of its key signaling molecules. Tα1 is a 28-amino acid peptide that contributes to immune system regulation, promoting T-cell maturation, differentiation, and function. It has been developed as a pharmaceutical drug (Thymalfasin/Zadaxin) by SciClone Pharmaceuticals and is approved in over 35 countries; primarily in Asia, South America, and Eastern Europe, for the treatment of chronic hepatitis B, chronic hepatitis C (as an adjunct to interferon), and as a vaccine adjuvant for immunocompromised patients. Thymosin Alpha-1 has also been studied extensively for cancer immunotherapy (as an immune adjuvant with chemotherapy), sepsis, HIV/AIDS, and most recently as an immunomodulatory treatment during COVID-19. A key feature of Tα1 is its ability to enhance immune function without causing the dangerous overactivation or cytokine storms associated with some immunostimulatory agents — it is a true immunomodulator rather than a simple immunostimulant.
Key Takeaways: Thymosin Alpha-1
- Strongest evidence supports Thymosin Alpha-1 for chronic hepatitis b treatment and hepatitis c adjunct therapy
- Research doses typically range from 1600 to 1600 mcg via subcutaneous injection
- 3 benefits with strong evidence, 3 moderate, 0 preliminary
- Half-life: Approximately 2 hours
- 5 cited research studies in this guide
Mechanism of Action
Thymosin Alpha-1 exerts its immunomodulatory effects through multiple interconnected pathways targeting both innate and adaptive immunity. In the adaptive immune system, Tα1 promotes the maturation and differentiation of T-cell precursors (thymocytes) into functional CD4+ helper T-cells and CD8+ cytotoxic T-cells. It activates T-cells by stimulating the expression of IL-2 receptors (CD25) and enhancing IL-2 production, driving T-cell proliferation and effector function. Tα1 also promotes the differentiation of CD4+ T-cells toward a Th1 phenotype, favoring cell-mediated immunity critical for antiviral and antitumor defense. In innate immunity, Tα1 activates Toll-like receptors (particularly TLR2, TLR5, and TLR9) on dendritic cells, macrophages, and natural killer cells, enhancing pathogen recognition and antigen presentation. This TLR activation stimulates the production of interferon-alpha, IL-12, and other Th1-promoting cytokines. Tα1 enhances natural killer (NK) cell cytotoxicity and antibody-dependent cellular cytotoxicity (ADCC). Critically, Tα1 simultaneously upregulates regulatory T-cell (Treg) function through indoleamine 2,3-dioxygenase (IDO) induction in dendritic cells, preventing excessive inflammatory responses. This dual action, enhancing immune effector function while maintaining immune regulation; is what distinguishes Tα1 as an immunomodulator rather than a simple immunostimulant, and explains its safety in conditions like sepsis where immune overstimulation can be fatal.
Research Benefits
Thymosin Alpha-1 at a Glance
Thymosin Alpha-1 exerts its immunomodulatory effects through multiple interconnected pathways targeting both innate and adaptive immunity.
Chronic Hepatitis B Treatment
Strong EvidenceApproved in 35+ countries for chronic hepatitis B. Clinical trials demonstrate improved viral clearance, HBeAg seroconversion, and sustained virological response when used alone or combined with interferon.
Hepatitis C Adjunct Therapy
Strong EvidenceApproved as an adjunct to interferon-alpha for chronic hepatitis C. Combination therapy shows improved sustained virological response rates compared to interferon alone, particularly in difficult-to-treat genotypes.
Vaccine Adjuvant / Immunocompromised
Strong EvidenceEnhances vaccine efficacy in immunocompromised patients (elderly, dialysis, HIV+, cancer) who respond poorly to standard vaccination. Improves antibody responses and T-cell-mediated immunity to vaccines.
Cancer Immunotherapy Adjunct
Moderate EvidenceUsed as an immune adjuvant alongside chemotherapy in several cancer types (hepatocellular carcinoma, melanoma, NSCLC). Enhances anti-tumor immunity while potentially reducing chemotherapy-related immunosuppression.
Sepsis Immune Restoration
Moderate EvidenceClinical studies show Tα1 reduces mortality in severe sepsis by restoring immune function in the immunosuppressive phase of sepsis, improving T-cell counts and reducing secondary infections.
Balanced Immunomodulation (No Overstimulation)
Moderate EvidenceUniquely enhances immune effector function while simultaneously upregulating regulatory T-cells, preventing cytokine storm and immune overstimulation. This makes it safe in conditions where immune balance is critical.
Research Dosing Protocols
Research Purposes Only: All content is for informational and research purposes only. This site does not provide medical advice, diagnosis, or treatment. Consult a qualified healthcare professional before using any peptide or supplement.
| Research Protocol | Dose Range | Route |
|---|---|---|
| Standard therapeutic dose (Zadaxin labeling) | 1600–1600 mcg | Subcutaneous injection |
| Hepatitis B protocol | 1600–1600 mcg | Subcutaneous injection, twice weekly |
| Immune support / adjuvant protocol | 1600–3200 mcg | Subcutaneous injection |
Frequency
Twice weekly (standard); daily in acute/critical settings (sepsis)
Timing
No specific timing requirements; can be administered any time of day
Cycle Length
6-12 months for hepatitis treatment; variable for other indications
Research Notes
- 1The standard pharmaceutical dose (Zadaxin) is 1.6 mg (1,600 mcg) subcutaneous twice weekly.
- 2For hepatitis B, typical treatment courses are 6-12 months.
- 3In sepsis and critical care, daily dosing has been studied for 5-14 day courses.
- 4Tα1 does not cause immune overstimulation or cytokine storms — safe for use in sepsis.
- 5Can be used as a vaccine adjuvant administered alongside or before vaccination.
- 6Well-tolerated in immunocompromised patients including those with HIV/AIDS.
Reconstitution Guide
Standard Reconstitution
Vial Size
1.6 mg
Bacteriostatic Water
1 mL
Concentration
16 mcg
per 0.1 mL (10 units)
Step-by-Step Guide
Gather Materials
Thymosin Alpha-1 vial, bacteriostatic water, alcohol swabs, insulin syringes.
Equilibrate Temperature
Remove the vial from storage and allow it to reach room temperature (5-10 minutes).
Sanitize
Swab the rubber stopper of both the peptide vial and bacteriostatic water vial with alcohol.
Draw Water
Draw 1 mL of bacteriostatic water into a syringe.
Add Water to Vial
Insert the needle into the peptide vial and direct the water stream against the glass wall — not directly onto the powder.
Mix Gently
Swirl the vial gently until the powder is fully dissolved. Never shake. The solution should be clear and colorless.
Store Properly
Refrigerate at Room temperature (lyophilized); refrigerated after reconstitution. Zadaxin: stable at room temperature (lyophilized). Reconstituted: use within 24 hours..
Storage Temperature
Room temperature (lyophilized); refrigerated after reconstitution
Shelf Life
Zadaxin: stable at room temperature (lyophilized). Reconstituted: use within 24 hours.
Important Notes
- •Zadaxin is supplied as a lyophilized powder with pre-filled diluent syringe.
- •Reconstitute by adding diluent to the vial and gently swirling.
- •Research-grade Tα1 should be reconstituted with bacteriostatic water.
- •Solution should be clear and colorless after reconstitution.
- •Lyophilized Tα1 is particularly stable; can be stored at room temperature.
Thymosin Alpha-1 Dosing Calculator
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Thymosin Alpha-1 Reconstitution Calculator
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Safety & Side Effects
Reported Side Effects
- !Injection site reactions (mild redness, discomfort, most common)
- !Mild flu-like symptoms (infrequent, typically with initial doses)
- !Fatigue (rare)
- !Mild fever (rare, more common in sepsis/critical care settings)
- !No significant organ toxicity in clinical studies
- !No immune overstimulation or cytokine storm risk
- !Exceptionally well-tolerated — one of the safest immunomodulatory agents available
- !No significant hematological, hepatic, or renal adverse effects
Potential Interactions
- ⚡complementary with interferon-alpha for hepatitis treatment.
- ⚡Enhances immune response to vaccines, used intentionally as vaccine adjuvant.
- ⚡May enhance the efficacy of checkpoint inhibitor immunotherapy (theoretical, under investigation).
- ⚡Caution with immunosuppressive medications; Tα1 may counteract their effects.
- ⚡No significant adverse interactions reported in clinical use.
- ⚡Compatible with standard chemotherapy regimens (used as adjunct in oncology).
Important: Side effects and interactions listed here are compiled from published research and community reports. This is not a complete list. No formal drug interaction studies have been conducted for most research peptides. Always consult a qualified healthcare provider.
Research Studies
The following studies are referenced in this profile. PubMed IDs are provided where available for independent verification.
Thymalfasin (thymosin alpha 1) for treatment of chronic hepatitis B
thorough review of clinical data supporting Tα1 for chronic hepatitis B, demonstrating improved HBeAg seroconversion, viral suppression, and sustained response rates across multiple controlled trials.
Thymosin alpha-1 reduces mortality of severe sepsis: a meta-analysis
Meta-analysis of randomized controlled trials showing Tα1 significantly reduces 28-day mortality in severe sepsis through immune restoration, with improved T-cell counts and reduced secondary infection rates.
Thymosin alpha 1 activates dendritic cells through Toll-like receptors
Elucidated the molecular mechanism by which Tα1 activates innate immunity through TLR2/TLR9 on dendritic cells, enhancing antigen presentation and Th1 cytokine production while inducing tolerogenic pathways via IDO.
Thymosin alpha-1 as a cancer vaccine adjuvant
Reviewed clinical evidence for Tα1 as an immune adjuvant in cancer treatment, showing enhanced anti-tumor immunity and improved outcomes when combined with chemotherapy in hepatocellular carcinoma and melanoma.
Thymosin alpha 1 treatment of immunocompromised patients for vaccination enhancement
Demonstrated Tα1 enhances vaccine-induced antibody responses and T-cell immunity in immunocompromised populations including elderly, dialysis patients, and HIV-positive individuals.
Note: This is not an exhaustive list of all published research. Studies are selected for relevance and quality. Click PubMed IDs to verify sources independently. Inclusion does not imply endorsement of the peptide for any clinical use.
Frequently Asked Questions
Thymosin Alpha-1 is a 28-amino acid peptide naturally produced by the thymus gland. It is a potent immunomodulator approved in over 35 countries for hepatitis B, hepatitis C, and vaccine enhancement. It boosts immune function without causing dangerous overactivation.
Thymosin Alpha-1 (as Zadaxin/Thymalfasin) is approved in over 35 countries but is NOT FDA-approved in the United States. It has been granted FDA orphan drug status for certain indications. It is available in the US through compounding pharmacies.
Despite both being thymus-derived peptides, they have entirely different mechanisms. Thymosin Alpha-1 is an immunomodulator that enhances T-cell and dendritic cell function. Thymosin Beta-4 (TB-500) is involved in cell migration, wound healing, and tissue repair through actin regulation. They target different systems.
No. A unique property of Tα1 is that it enhances immune effector function while simultaneously activating regulatory T-cells and tolerogenic pathways. This dual action prevents the immune overactivation and cytokine storms that can occur with other immunostimulants. This is why it is safe for use even in sepsis.
Tα1 has been studied in people with chronic hepatitis B/C, immunocompromised patients who respond poorly to vaccines, cancer patients undergoing chemotherapy, and critically ill patients with sepsis. It is also researched for general immune support in aging (immunosenescence).
Immune parameter improvements (T-cell counts, NK cell activity) can be measured within 1-2 weeks. For hepatitis treatment, full clinical courses are typically 6-12 months. For vaccine adjuvant use, it is given around the time of vaccination for enhanced antibody response.
Research & Educational Use Only
All content is for informational and research purposes only. This site does not provide medical advice, diagnosis, or treatment. Consult a qualified healthcare professional before using any peptide or supplement.
The information presented here is compiled from published research studies and is intended for informational purposes only. Individual results may vary. Always consult with a licensed healthcare provider.