Immune & gut
Thymosin alpha-1, simplified.
Also called Tα1, Zadaxin
Human studiesAn immune-boosting peptide from the thymus gland, approved in dozens of countries but not the US.
- Size
- 28 amino acids
- How it is taken
- Injection
- Status
- Approved abroad, not in the US
- Available sizes
- Vials: 5 mg, 10 mg · Capsules: 500 mcg
What is it?
The thymus is where some immune cells learn their job. Thymosin alpha-1 helps those T cells mature and respond.
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What studies show
- In peopleIt is approved in many countries to support treatment of hepatitis B and C.
- In peopleIt has been studied alongside vaccines and in serious infections, with mixed results.
What we don’t know yet
- Whether it helps healthy people with "immune support".
Side effects and cautions
- Generally well tolerated in trials.
Is it legal?
Not FDA-approved. Included in the 2026 HHS compounding plan.
Dosage & schedule evidence
How to read published schedules
Third-party protocols are not established clinical dosing standards. Safe human dose, frequency, and duration may be unknown. Research findings may not translate to safe or effective personal use.
| Measurement | Meaning |
|---|---|
| 1 mg | 1,000 mcg (mass) |
| 100 U-100 units | 1 mL (volume, not dose) |
See third-party published protocols ↗ for research context. North Star does not validate these schedules.
Consult your doctor before considering any peptide for personal use. Educational only, not administration guidance.
Common questions
What is Thymosin alpha-1?
An immune-boosting peptide from the thymus gland, approved in dozens of countries but not the US. The thymus is where some immune cells learn their job. Thymosin alpha-1 helps those T cells mature and respond.
What does the research say about Thymosin alpha-1?
It is approved in many countries to support treatment of hepatitis B and C. It has been studied alongside vaccines and in serious infections, with mixed results.
Is Thymosin alpha-1 FDA approved?
Not FDA-approved. Included in the 2026 HHS compounding plan.
What are the side effects of Thymosin alpha-1?
Generally well tolerated in trials.
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This page explains published research in plain language. It is not medical advice, a diagnosis, or a recommendation to take anything, and it does not give dosing. Most peptides here are not FDA-approved, and products sold online vary widely in purity. Rules around peptides are changing, so check the current status and talk with a licensed clinician before starting anything. Last reviewed 2026-10-19.