Trusted by over 10K subscribers
    Free & discreet shipping on all prescriptions
    Affordable pricing with no hidden fees
    FDA-regulated pharmacies
    100% online process
    Trusted by over 10K subscribers
    Free & discreet shipping on all prescriptions
    Affordable pricing with no hidden fees
    FDA-regulated pharmacies
    100% online process
    Trusted by over 10K subscribers
    Free & discreet shipping on all prescriptions
    Affordable pricing with no hidden fees
    FDA-regulated pharmacies
    100% online process
    HomeMedication GuideThymalfasin safety
    Immunomodulatory peptideInvestigational / Not FDA-Approved

    Thymosin Alpha-1: Patient Information & Safety Notes

    Also known as TA1, Zadaxin, Thymosin alpha 1

    Other names: ta1, zadaxin, thymalfasin

    Thymosin alpha-1 (thymalfasin, brand: Zadaxin) is a synthetic 28-amino-acid peptide that modulates immune function by stimulating T-cell maturation and natural killer cell activity. It is approved for hepatitis B and C in some countries outside the US. It is not FDA-approved in the United States for standard indications.

    NOT FDA-approved in the United States for standard therapeutic indications. Thymalfasin (Zadaxin) is approved in some countries for hepatitis and as an adjunct in cancer treatment. A compassionate use/IND pathway may apply in certain US clinical contexts.
    Reviewed by the OmniRx Health clinical teamLast reviewed Jul 4, 2026

    In plain language

    What Thymalfasin is used for

    • Investigated for immune support in chronic infections, cancer adjunct therapy, and autoimmune regulation

    Taking this medicine

    How it is administered

    • Subcutaneous injection

    Read before you decide

    Risks and precautions

    Risks and warnings

    • Headache
    • Mild allergic reactions or flu-like symptoms
    • Injection site irritation

    Who should not take it

    • History of organ transplant (immune stimulation may risk rejection)
    • Active severe flare of autoimmune disorder
    • Pregnancy

    Common questions

    Patient questions

    Is thymosin alpha-1 FDA-approved in the United States?

    No. Thymosin alpha-1 (Zadaxin) is approved in some countries but is not FDA-approved for routine therapeutic use in the United States.

    Explore treatment hubs

    This information is educational — not medical advice.

    This page is provided for general educational purposes and summarizes publicly available data from sources such as the U.S. Food & Drug Administration. It is not a substitute for the judgment of a licensed clinician and should not be used to start, stop, or change any medication. It may be incomplete or out of date, and individual circumstances vary. Always talk with your prescriber or pharmacist about your specific medications and health conditions. If you think you may have a medical emergency, call 911.