Immune · Inflammation
Thymosin Alpha-1
Also known as: Thymalfasin, Zadaxin, Tα1
An immune-modulating peptide approved across many international jurisdictions for hepatitis B and adjunctive use, and not approved by the FDA.
Sign in to add to watchlistEvidence strength
Strength of human clinical evidence — A (strongest) to D (mostly preclinical). This reflects research maturity, not safety or suitability.
Vial Theory provides educational research summaries only. Content is not medical advice, diagnosis, treatment, dosing guidance, or individualized suitability screening. Regulatory status can change over time and varies by jurisdiction.
Key Takeaways
- ›Thymosin alpha-1 is a natural immune-modulating peptide, approved in many countries but not by the FDA.
- ›Its main evidence is in hepatitis B and sepsis, with mixed and hard-to-replicate results.
- ›Decades of use suggest a generally mild safety profile, mostly from countries where it's approved.
- ›General 'immune optimization' and longevity claims exceed the studied indications.
- ›It is not FDA-approved. Speak with a licensed healthcare professional before any health decisions.
What It Is
Thymosin alpha-1 is a 28-amino-acid acetylated peptide originally isolated from thymic tissue extract by Allan Goldstein and colleagues in the 1970s. The synthetic version (thymalfasin) is chemically identical to the endogenous peptide. The compound was developed clinically as Zadaxin by SciClone Pharmaceuticals.
Mechanistically, thymosin alpha-1 modulates innate and adaptive immune function through effects on dendritic cells, T-cell maturation, Toll-like-receptor signaling, and cytokine production. The peptide does not act through a single high-affinity receptor in the way many hormones do; instead, its effects are distributed across multiple immune-cell populations, which complicates clean mechanistic characterization but underlies its breadth of investigated indications.
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Disclaimer: This content is for educational and research purposes only and is not medical advice. Always consult a licensed healthcare professional before making health-related decisions.