Question 1

What is thymosin alpha-1?

Accepted Answer

Thymosin alpha-1 (Tα1) is a 28-amino acid peptide originally isolated from the thymus gland. It is a naturally occurring peptide that plays a central role in T-cell maturation and immune regulation. As the thymus involutes with age (losing function from the mid-20s onward), Tα1 levels decline — correlating with the immunosenescence seen in aging. Synthetic thymosin alpha-1 (brand: Zadaxin) is approved in over 37 countries for hepatitis B, hepatitis C, and malignant melanoma.

Question 2

Is thymosin alpha-1 FDA approved?

Accepted Answer

Thymosin alpha-1 (Zadaxin) is approved in 37+ countries but has not received FDA approval in the United States as of 2026. In the US, it is available off-label through licensed compounding pharmacies with a physician prescription. Its international approval record and decades of clinical use outside the US provide a substantial safety and efficacy foundation that supports US off-label prescribing.

Question 3

What conditions is thymosin alpha-1 used for in the US?

Accepted Answer

Off-label uses include: chronic viral infections (hepatitis B/C, EBV, CMV, chronic Lyme), post-COVID immune dysregulation and long-COVID, cancer adjunct therapy during chemotherapy, immune optimization in aging patients, and select autoimmune conditions under careful physician supervision. It is not a first-line treatment for any of these — it is typically used alongside or after conventional treatments.

Question 4

How is thymosin alpha-1 administered?

Accepted Answer

Thymosin alpha-1 is administered by subcutaneous injection. Standard dosing is 1.6mg twice weekly. Protocols vary by condition and physician — some acute protocols use more frequent dosing for 4–6 weeks; maintenance protocols may dose once weekly. The injection is small volume and generally well tolerated.

Question 5

What are the side effects of thymosin alpha-1?

Accepted Answer

Thymosin alpha-1 has an excellent safety profile — it is a naturally occurring peptide that the body already produces. The most common side effects are mild injection site reactions (redness, swelling). Rare systemic reactions have been reported. In patients with active autoimmune conditions, careful monitoring is appropriate as immune modulation can have unpredictable effects on autoimmune disease activity.

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