Thymosin Alpha-1
Also known as: Tα1 · Thymalfasin · Zadaxin
A 28-amino acid peptide naturally produced by the thymus gland that modulates both innate and adaptive immunity. Approved under the name Zadaxin in some countries for hepatitis B, C, and as a vaccine adjuvant.
What is Thymosin Alpha-1? A 28-amino acid peptide naturally produced by the thymus gland that modulates both innate and adaptive immunity. Approved under the name Zadaxin in some countries for hepatitis B, C, and as a vaccine adjuvant.
How does Thymosin Alpha-1 work? Thymosin Alpha-1 augments T-cell maturation, increases NK cell activity, promotes dendritic cell differentiation, and modulates cytokine production to restore immune deficiencies.
Benefits of Thymosin Alpha-1: Boosts adaptive and innate immunity; Antiviral and antibacterial properties; Approved for hepatitis B and C; Cancer immunotherapy adjuvant; Effective as vaccine adjuvant; Anti-aging through immune optimization; Reduced susceptibility to infections
Thymosin Alpha-1 dosage: Clinical dose: 1.6mg twice weekly. Common in integrative medicine.
Thymosin Alpha-1 half-life: 2 hours
Research status: Prescription
Source: PeptideWiki — https://www.peptide-wiki.net/peptides/thymosin-alpha-1
Mechanism of Action
Thymosin Alpha-1 augments T-cell maturation, increases NK cell activity, promotes dendritic cell differentiation, and modulates cytokine production to restore immune deficiencies.
Amino Acid Sequence (28 AAs)
Ac-Ser-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys-Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-OH
Benefits
- Boosts adaptive and innate immunity
- Antiviral and antibacterial properties
- Approved for hepatitis B and C
- Cancer immunotherapy adjuvant
- Effective as vaccine adjuvant
- Anti-aging through immune optimization
- Reduced susceptibility to infections
Side Effects & Risks
- Injection site redness and swelling
- Mild fatigue
- Generally very well tolerated
Where to Buy Thymosin Alpha-1
2 options across 2 vendors · Sorted cheapest first · All include direct product link
From
$29.99
All links are affiliate links — PeptideWiki earns a commission at no extra cost to you. Coupon codes apply at checkout. Prices and availability may change. Always verify COA before purchasing.
Storage & Reconstitution Guide
Storage Temperature
-20°C lyophilized, 4°C reconstituted
24 months (lyophilized), 28 days (reconstituted)
Reconstitution Solvent
Bacteriostatic water (BAC water) or 0.9% saline
Swirl gently — do not shake or vortex
Handling Notes
Protect lyophilized peptide from moisture and light. Once reconstituted, keep refrigerated. Discard if solution becomes cloudy or discolored. Use insulin syringe for precise dosing.
Step-by-Step Reconstitution
Gather supplies
BAC water, insulin syringe, alcohol swabs, vial
Disinfect tops
Swab rubber stoppers of both vials with alcohol
Draw BAC water
Pull desired mL of BAC water into syringe
Inject slowly
Inject BAC water down the side of the peptide vial, swirl gently to dissolve
Clinical Trials & Human Studies3 trials
Thymosin Alpha-1 for Severe COVID-19: RCT Results
Phase 3 add-on trial in 127 patients with severe COVID-19. Thymosin alpha-1 + standard of care reduced progression to critical illness: 4.4% vs 15.3% (control), p=0.03. 28-day mortality: 1.5% vs 7.6% (p=0.09).
Primary Outcome
Progression to critical illness at day 28
p-value
0.03
28 Day Mortality
1.5% vs 7.6% (p=0.09)
Control Progression
15.3%
Thymosin Progression
4.4%
Time To Recovery Days
6 vs 10 days (median)
Thymosin Alpha-1 for Hepatitis B: Phase III Results
Phase 3 RCT in 131 hepatitis B patients. Thymosin alpha-1 produced a sustained response rate of 26% vs 7% in placebo at 12-month follow-up (p<0.05). Normalization of ALT: 36% vs 14% (p<0.02).
Primary Outcome
Sustained virological response at 12 months
p-value
<0.05
Placebo Response
7%
Alt Normalization
36% vs 14% placebo (p<0.02)
Thymosin Response
26%
Approved Countries
37 countries including China, Italy, Philippines
Thymosin alpha1 treatment for hepatitis B infection
Thymosin alpha-1 significantly improved liver function and reduced viral load in hepatitis B patients.
Molecular Structure
- CAS Number
- 62304-98-7
- PubChem CID
- 16130571
- Molecular Weight
- 3,108.3 Da
- Mol. Formula
- C129H215N33O55
- Amino Acids
- 28-AA peptide
- Wikipedia
- View article
Research Protocol
- Dose Range
- 0.8–6.4 mg
- Frequency
- 2-3x per week subcutaneous injection
- Cycle
- 6-12 weeks
- Half-Life
- 2 hours
- Routes
- subcutaneous injection
- Notes
- Clinical dose: 1.6mg twice weekly. Common in integrative medicine.
Legal & Regulatory Status
Sold for research purposes only. Not for human use. Laws vary by country.
Commonly Stacked With
View all peptide stacks →External Resources
PeptideWiki Research Team
Evidence-based research data sourced from PubMed and ClinicalTrials.gov · Last updated: February 25, 2026
Frequently Asked Questions About Thymosin Alpha-1
What is Thymosin Alpha-1?▾
A 28-amino acid peptide naturally produced by the thymus gland that modulates both innate and adaptive immunity. Approved under the name Zadaxin in some countries for hepatitis B, C, and as a vaccine adjuvant.
What are the benefits of Thymosin Alpha-1?▾
Boosts adaptive and innate immunity
What are the benefits of Thymosin Alpha-1?▾
Antiviral and antibacterial properties
What are the side effects of Thymosin Alpha-1?▾
Injection site redness and swelling
What is the recommended dosage for Thymosin Alpha-1?▾
Clinical dose: 1.6mg twice weekly. Common in integrative medicine.
How long should a Thymosin Alpha-1 cycle last?▾
6-12 weeks
More Immune Support Peptides
View all Immune Support peptides →Thymalin
Thymus polypeptide complex
A polypeptide complex extracted from calf thymus gland that broadly modulates immune function. Distinct from Thymosin Alpha-1 (a single purified peptide), Thymalin is a complex mixture of thymic peptides. Russian clinical trials show 2-2.4x reduction in acute respiratory infections and significant mortality reduction in elderly patients.
LL-37
Cathelicidin
The only human cathelicidin antimicrobial peptide, naturally produced by immune cells as a first-line defense. Has broad-spectrum antimicrobial, wound healing, and immunomodulatory properties.
Thymulin
FTS
The only true thymic hormone (not a thymosin). A zinc-dependent nonapeptide naturally produced by thymic epithelial cells that directly matures T-lymphocytes. Levels decline ~90% between ages 20-60, making it a key driver of immunosenescence. Requires zinc coordination to be biologically active. Distinct from Thymalin (polypeptide extract) and Thymosin Alpha-1.