Thymosin Alpha-1 — Wolverine Health

How it works

A 28-amino-acid peptide originally isolated from calf thymic tissue. It modulates both innate and adaptive immunity — upregulating dendritic cell maturation, increasing T-cell activity, and enhancing natural killer cell function. Approved in over 35 countries under the brand name Zadaxin for viral hepatitis and as an adjuvant in immunocompromised patients. Not FDA-approved. It occupies an unusual regulatory position: extensive international clinical history, no approved US indication, compoundable as a 503A bulk substance.

FDA status: Not FDA-approved in the US. Approved in 35+ countries for viral hepatitis (Zadaxin). Compoundable by 503A pharmacies in the US as it has no active FDA NDA.
WADA status: Permitted in sport
Route: subcutaneous injection

Key studies

Thymosin alpha 1: biological activities and clinical applications — Garaci et al.

Thymosin alpha-1 is a 28-amino-acid thymic peptide that enhances T-lymphocyte function, natural killer cell activity, and cytokine production in immunodeficiency and chronic infection models.

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Research on Thymosin Alpha-1

Thymosin peptides and the thymus: what the immune connection actually means

WADA

The thymus trains your T-cells. It shrinks from a small fist to a patch of fat by your fifties. Thymosin α-1 is the most-studied peptide derived from it. Here is what the immune connection is, and where the largest sepsis trial just rewrote the file.

Thymosin Alpha-1: the immune system's slowest burn

WADA

Thymosin Alpha-1 has the deepest human trial record of any peptide on the longevity menu, including a 2025 multicentre sepsis trial in BMJ. The populations studied are not the ones buying it. Here is what the evidence shows and where the regulatory line actually falls.

Thymosin Alpha-1: Immune Modulation Research and Regulatory Overview

WADA

Science-journalism overview of Thymosin Alpha-1 — the thymic peptide with extensive clinical development history in immunology, its evidence base in infections and cancer, and why it occupies a distinct regulatory category in the United States.