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Thymosin Alpha-1

Immune-signaling peptide · 28 amino acids
What it is

Thymosin alpha-1 is a 28-amino-acid immune-signaling peptide first isolated from thymosin fraction 5 of the thymus; a synthetic form (thymalfasin) has been used in clinical research for infections and immune support.[1][2][3]

Origin: Isolated from calf and other species’ thymosin fraction 5 by Low, Goldstein and colleagues; later made synthetically for clinical study as thymalfasin.[1][2]

What researchers study it for

Research areas

Clinical reviews and trials point to several research angles.

  • Chronic hepatitis B, alone or with other antivirals, in clinical studies and reviews[3][4]
  • Chronic hepatitis C and other infectious-disease settings as an immune modulator[4][5]
  • Broader immune restoration questions in immunocompromised states, sepsis and vaccine-adjuvant research[2][5]
  • Exploratory work in COVID-19 and other infections[2]

Evidence level

Level 3 of 4: Small human trialsClinical trials and reviews describe thymosin alpha-1 (thymalfasin) in hepatitis and other infection settings, without a current U.S. FDA-approved product.[3][4][5][6]

Why so few human trials?

Cautions

Studies and regulators point to several reasons for care.

  • FDA says it doesn’t have enough safety information to understand the risks of thymosin alpha-1[6]
  • Response rates and study designs in hepatitis research vary across trials[3][4]

Thymosin alpha-1 is not FDA approved.[6]

Also called

Thymosin Alpha-1 goes by several names.

  • Thymalfasin, the synthetic clinical name[4]
  • Tα1 or Ta1[2][6]
  • Thymosin α1[1][2]

Good to know

Reviews describe thymosin alpha-1 as helping T-cell and innate immune signaling rather than acting like a classic antibiotic.[2][5]

Handling

Storage basics General

These general basics apply to most freeze-dried research peptides.

Most research peptides come as a freeze-dried powder in a sealed vial
Unmixed vials are generally kept cold, dry, and away from light
Mixed solutions are generally refrigerated, since they are less stable than the dry powder
Peptides 101For mixing basicsNPL Dose CalculatorTo work out concentration after mixing
Go deeper

Sources and studies

These studies and official pages are the research behind this profile.

  1. 1Isolation of thymosin alpha 1 from thymosin fraction 5 of different species by high-performance liquid chromatographyLow TL, et al. (1983) · Journal of Chromatography
  2. 2Thymosin alpha 1: A comprehensive review of the literatureDominari A, et al. (2020) · World Journal of Virology
  3. 3Thymosin alpha-1 treatment in chronic hepatitis BWu X, et al. (2015) · Expert Opinion on Biological Therapy
  4. 4Thymalfasin in the treatment of hepatitis B and CCiancio A, Rizzetto M (2010) · Annals of the New York Academy of Sciences
  5. 5Historical review of thymosin α1 in infectious diseasesCamerini R, Garaci E (2015) · Expert Opinion on Biological Therapy
  6. 6Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety RisksU.S. Food and Drug Administration (2026)