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.

Why people take it

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

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.

In practice Off-label

Used in longer courses during illness season or alongside infection
Prescribed in countries where it is approved; obtained otherwise elsewhere

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

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

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 →

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.