Thymosin Alpha-1

Tα1 · Zadaxin · Thymalfasin

A thymus-derived peptide approved in a number of countries as an immune modulator, notably for hepatitis B and C.

Prescription / compounded. Approved or legitimately prescribed for at least one indication. Dose information below is reference material, not a recommendation — follow your prescriber and the product labelling.

At a glance

Category: Immune
Half-life: ~2 hours
Typical vial sizes: 5 mg · 10 mg
Commonly cited dose: 1600–3200 mcg
Frequency: twice weekly
Routes: Subcutaneous

A 5 mg vial, worked through.

Reconstituting a 5 mg vial of Thymosin Alpha-1 with 2 mL of bacteriostatic water gives 2.5 mg/mL. A 1600 mcg dose is then:

64units(0.64 mL) — about 3 doses per vial

Storage

Lyophilised (unmixed): Refrigerated.
Reconstituted: Refrigerate at 2–8°C.

What people log it against

Outcomes users commonly track alongside this compound. Listing them is not a claim that it produces them.

Immune support
Recovery tracking

Read alongside Thymosin Alpha-1

Compounds this one is commonly compared with, combined with, or mistaken for. Listing a pairing is not a suggestion to run them together.

TB-500Research use onlyBoth carry the thymosin name and are unrelated compounds — TB-500 is a thymosin beta-4 fragment, thymosin alpha-1 is a separate immune peptide with its own approvals.

References

Each source below establishes only the specific claim noted with it, last checked 2026-08-13. Dose ranges, frequencies and storage times reflect what circulating protocols commonly state and are not established by these references.

Pharmacokinetics of thymosin alpha1 after subcutaneous injection, 1999 — PMID 10027483
Healthy volunteers, three SC formulations incl. Zadaxin. Tmax 1-2 h; the authors infer a "short elimination half-life of less than 3 hours" from the lack of accumulation between single and multiple dosing. Note this is an upper BOUND, not a measured value — 2 h is consistent with it but is not itself stated in the paper.

Run your own numbers

Pick Thymosin Alpha-1 from the preset list to start from a typical vial.

Your vial

Peptide in vial

As printed on the vial label

Bacteriostatic water added

How much you inject into the vial

Dose you want

mcg

1000 mcg = 1 mg

Syringe size

Start from a peptide

Fills in a common vial size and the low end of commonly cited protocols. Always check against your own vial.

Draw this much

5units

on a 1 mL U-100 insulin syringe

Concentration: 5 mg/mL
Volume: 0.05 mL
Doses in this vial: 40

Keep this vial. VialPal holds the concentration, counts down the doses left in it, and logs the ones you actually took.

VialPal does the arithmetic — it does not tell you what to take. Dose decisions belong between you and a qualified clinician.