Thymosin alpha-1

Also called Thymalfasin, Zadaxin, Tα1, Thymosin α1

Studied in:Immune

Educational only, not medical advice. Dosaly reports what has been studied; it isn't a recommendation to use Thymosin alpha-1 or any amount of it. Talk to a clinician.

Approved as a prescription medicine (thymalfasin, Zadaxin) in a number of countries outside the US and EU; not approved by the FDA or EMA (as of October 2026).

Research applications

Chronic hepatitis B and C (clinical trials)
Vaccine response, as an adjuvant (clinical trials)
Alongside cancer treatment (some clinical trials)
Severe infections, including sepsis and COVID-19 (clinical trials)
T-cell and toll-like receptor signalling (lab studies)

What studies have looked at, not proven uses.

What it is

Thymosin alpha-1 is a peptide first found in the thymus, an organ of the immune system. It's been tested in many human trials for infections and immune support, though many were small.

More detail

Thymosin alpha-1 is a 28-amino-acid peptide first isolated from thymus tissue; its synthetic form is called thymalfasin. It is described as an immune modulator that acts on T cells and on toll-like receptors on immune cells. It has been studied in clinical trials for chronic hepatitis B and C, as a vaccine adjuvant, alongside other treatments in some cancers, and in severe infections including sepsis and COVID-19. Meta-analyses have reported some positive results, but many of the underlying trials were small or open-label, and the authors call for larger randomized trials. It has more human research behind it than most peptides in this library.

Evidence listed here

3 reviews

Results from cells and animals often don't carry over to people. How to read peptide research

Molecular info

Class: Thymic peptide
Length: 28 amino acids
Sequence: Ac-Ser-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys-Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-OH
Research areas: Immune

Starts with an acetyl group. Synthetic form: thymalfasin.