Thymosin-α1

Immune Approved · 30+ countries Human trials

Also called Thymalfasin, Zadaxin, Tα1

A 28-amino-acid peptide naturally made in the thymus. It helps T cells mature and strengthens the response of immune cells to viruses and tumors. It has been studied in hepatitis B and C, sepsis, cancer and as a vaccine booster.

Evidence at a glance

Evidence: Human trials — Studied in people
Status: An approved medicine in 30+ countries
Dosing: A dose has been tested in humans

Approved abroad but never FDA-approved; evidence quality varies by indication.

What studies report

Improved response rates in chronic hepatitis B and C, often alongside other therapy
Improved survival signals in sepsis trials, including a large Chinese COVID-era study
Used as a vaccine adjuvant in older adults

How it works

Naturally produced by the thymus. Drives T-cell maturation and restores immune responsiveness that declines with age.

Binds a receptor on the cell surface and signals inward

Where it acts

Thymus

The library groups this compound under Immune. The diagram shows that target, not every tissue it reaches.

Illustrated

A close view of a few human lymphocytes with gently textured cell membranes, one partially cut away to reveal a large nucleus. Neutral immune cell anatomy.

AI-generated subject illustration; not a depiction of the compound or evidence of its effects.

Why people take it

Immunosenescence (age-related immune decline)Chronic hepatitis B and CAcute viral infectionAdjuvant in oncologyImmune support during infectionChronic hepatitis

Reasons people seek it out — not a list of proven effects.

In practice Off-label

Used in longer courses during illness season or alongside infection
Prescribed in countries where it is approved; obtained otherwise elsewhere
Appears in pre-mixed vials with BPC-157 and thymosin-β4

Reported real-world use, not evidence and not a recommendation.

Dosing

What was tested Evidence

1.6 mg twice weekly, subcutaneous6–12 monthsChronic hepatitis B and C trials→ Improved response rates, often alongside other therapy

What people report using Not evidence

1.6 mg twice weekly mirrors the trial schedule
Used in longer courses during illness season

Reported for reference, not as instruction. Nothing here is a recommendation to take anything, and most of these compounds are not approved for human use.

Status: Approved in more than 30 countries (Zadaxin), mainly for hepatitis B and C. Not FDA-approved.

Route: Subcutaneous injection, from reconstituted lyophilised powder
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
Formula: C129H215N33O55
Molecular weight: 3108.3 g/mol
CAS: 62304-98-7
Available as: 4.5 mg, 10 mg

View on PubChem →

Search PubMed for Thymosin-α1 → We link a live search rather than a fixed citation list, so it stays current and nothing here is a reference we have not checked.

Compared with

vs Thymogen →

Side-by-side pages for the compounds this one is most often confused with or taken alongside.

Educational information only. Nothing here is medical advice, a dosing protocol, or a recommendation to use any compound. Most entries describe substances not approved for human use. Talk to a licensed clinician before acting on anything you read here. How to read these entries.