Thymosin Alpha-1
Immune modulation
Status & caution. Approved as a drug (Zadaxin) in 30+ countries for hepatitis and as an immune adjuvant, but NOT FDA-approved in the US. Named in the 2026 US reclassification discussion but not among the 12 peptides FDA advanced to PCAC review; sold grey-market in the US. Has the strongest international regulatory track record of the 'research' peptides here, yet remains unapproved in the US.
At a glance
Indications & what it's studied for
Used internationally for chronic hepatitis B/C, as a vaccine adjuvant, and as immune support in some cancer settings; modulates T-cell function.
Contraindications & cautions
Caution in immunosuppressed transplant patients or autoimmune disease (it modulates immunity); pregnancy data limited.
Commonly reported dosing
Reported, not recommended. The following describes what appears in research literature and community use. It is not a protocol, and unapproved peptides have no validated human dosing.
Approved international products use defined subcutaneous regimens; US community dosing is extrapolated.
Routes of administration
Subcutaneous injection.
Don't combine with
Caution with immunosuppressants (opposing actions) and in autoimmune conditions.
Reported to stack with
Sometimes used alongside other recovery/longevity peptides; immune effects argue for medical oversight.
Note: "stacking" combines multiple agents and multiplies unknowns; popularity of a combination is not evidence of its safety.
What the research actually shows
Numerous international trials in hepatitis and as an immune adjuvant; this is a comparatively well-studied peptide globally.
Before acting on anything here, see Safety & the grey market and how to read a COA.