Thymosin Alpha-1
Thymosin Alpha-1 (Tα1) is a synthetic 28-amino acid peptide identical to the N-terminal fragment of prothymosin alpha, a thymic hormone, and is commercially available as thymalfasin (Zadaxin). It enhances adaptive immunity by activating toll-like receptor (TLR) signaling in dendritic cells, promoting Th1 cytokine responses, and restoring T-lymphocyte activity in immunocompromised states. It is approved as a pharmaceutical in approximately 35 countries — primarily for chronic hepatitis B, chronic hepatitis C (as adjunct to interferon), and as an immunomodulatory adjuvant in oncology — and was used at scale in China during the COVID-19 pandemic for severe cases based on its immunostimulatory profile. Evidence quality varies considerably by indication; hepatitis and oncology adjuvant data from formal trials are the most robust, while longevity and general wellness applications common in the research peptide community lack controlled human evidence.
Evidence last reviewed: 19 Apr 2026
Not a routine supplement — not recommended for self-directed use.
Information here is educational only, not a recommendation to use. See our Safety page.
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Evidence is from research or clinical settings — does not imply safety outside supervised contexts.
The evidence for Thymosin Alpha-1 is moderate, with strong data supporting its use in hepatitis and COVID-19. However, applications for general wellness and longevity are not well-supported by controlled studies.
Immune modulation in hepatitis BPatients with HBV-related cirrhosis · Systematic reviewModerate
Thymosin Alpha-1 combined with Entecavir improved HBV DNA undetectable rates and HBeAg loss rates compared to Entecavir alone.
Mortality reduction in COVID-19Moderate to critical COVID-19 patients · Systematic reviewModerate
Thymosin Alpha-1 therapy was associated with significantly lower mortality in COVID-19 patients.
Inflammation control in severe acute pancreatitisPatients with severe acute pancreatitis · Systematic reviewModerate
Thymosin Alpha-1 alleviated inflammation and prevented infection through immune regulation.
Augmentation of influenza antibody responseElderly men · RCTModerate
Thymosin Alpha-1 enhanced the antibody response to influenza vaccine in elderly men.
Combining Astragalus with Thymosin Alpha-1 can enhance immune function and provide anti-inflammatory defense. Astragalus is known for its immune-boosting and longevity properties, while Thymosin Alpha-1 supports immune modulation.