Thymosin alpha-1
Also called Thymalfasin, Zadaxin, Ta1.
Thymosin alpha-1 has no FDA-approved product. This page cites 2 sources, and the strongest evidence comes from human trials.
- Status
- No FDA-approved product
- Form
- Injection
- Half-life
- Not modeled
- Strongest evidence
- Human trials
- Cited claims
- 1
- Last updated
- November 6, 2026
What the evidence says
Each claim names the kind of study behind it, what it can't tell you, and where it comes from.
Human trials
The placebo-controlled TESTS trial in Chinese adults with sepsis found no clear reduction in 28-day mortality with subcutaneous thymosin alpha-1. Mortality was 23.4% versus 24.1%.
Limits: The modified intention-to-treat analysis included 1,089 participants across 22 Chinese centers. Corrected results remain inconclusive for mortality benefit. Findings in hospitalized patients with sepsis do not establish infection prevention, general immune improvement, or benefit in healthy users.
Regulatory status
United States
No FDA-approved thymosin alpha-1 product was identified. FDA lists the earlier nomination as withdrawn and identifies insufficient safety information, immunogenicity concerns, and peptide-characterization problems for proposed compounded preparations. Removal from Category 2 was not approval. The October 2026 HHS appendix does not include this molecule.