TA1
Natural peptide produced by the thymus that modulates immune function. Approved in multiple countries for hepatitis B and used as an immune adjuvant in some countries, with evidence from trials of varying quality.
Regulatory status (as of Sept 2026)
Not FDA-approved. Not among the peptides named in the 2026 PCAC actions.
See the FDA peptide regulatory tracker · Read our July 27, 2026 dispatch on the FDA PCAC peptide vote4 studies referenced · Last reviewed Oct 1, 2026 · Reviewed by The Peptide Dispatch Editorial Team · How we research & label content
Thymosin Alpha-1 is approved as a medicine in some countries outside the US, but not by the FDA. Natural peptide produced by the thymus that modulates immune function.
| Half-life | Not established in published research detailsNo published human PK data found; ~3 h for native Tα1 in rats (Shen 2019). Literature describes a 'short plasma half-life' requiring twice-weekly s.c. dosing. |
|---|---|
| How it's given in studies | Subcutaneous injection |
| Research stage | Approved outside US |
| Dosing | Published research: Clinical regimen is twice-weekly subcutaneous injection detailsClinical regimen is twice-weekly s.c. injection (Vitek 2025 describes this standard regimen). Used with entecavir in HBV cirrhosis RCTs (meta-analysis, 2020).Community-reportedCommunity-reported: 1.6 mg twice weekly, subcutaneous injection |
Published-research dosing is what was given in the cited studies (species and units as reported). Community-reported dosing is what users describe, not from clinical studies. Neither is a recommendation. Not medical advice.
Where each point comes from: Clinicalhuman trials and FDA labels Lab / animalrodent, cell and ex vivo studies Community-reporteduser experience and commonly used protocols, not from clinical studies
In plain terms: It is a thymus peptide thought to switch on immune cells through sensor receptors called Toll-like receptors. Proposed mechanism (review, Tao 2023): an immunostimulatory peptide that binds Toll-like receptors (TLR3/4/9) and activates downstream IRF3 and NF-κB signalling, promoting proliferation and activation of T cells, B cells, macrophages and NK cells.
How to read this: Each item below is an effect observed in research subjects in the cited studies — think of Dexter, our stand-in research subject. These are findings from the literature, not results you should expect, and not medical advice.
Community-reportedSome users report 1.6 mg twice weekly (subcutaneous injection). This is not a recommendation.
Side effects reported in studies are listed separately below.
Community reports are anecdotal, vary widely in product quality and purity, and are not medical advice. Talk to a licensed provider.
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| Peptide | Half-Life | Route | Research Status |
|---|---|---|---|
| Thymosin Alpha-1 | No published human PK data found; ~3 h for native Tα1 in rats (Shen 2019). Literature describes a 'short plasma half-life' requiring twice-weekly s.c. dosing. | Subcutaneous injection | Approved outside US |
| KPV | No published PK data found | Subcutaneous injection, Oral, Topical | Preclinical (animal) |
| LL-37 | Unknown | Subcutaneous injection | Phase 2 |
| Thymalin | No published PK data found | Intramuscular injection | Approved outside US |
| Thymopoietin II Fragment (TP-1) | Unknown | Subcutaneous injection | Preclinical (animal) |
Values reflect figures reported in published research. Compare any peptides side-by-side →
This peptide belongs to the Immune category. View All Immune Peptides
Anti-Aging, Healing
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Dosing, half-life figures, and mechanism descriptions on this page are compiled from peer-reviewed published research, with the species and study type stated where reported. Figures labeled “Dosing used in published research” describe what was given in those studies and do not constitute dosing recommendations for any human use. Each cited paper is listed with DOI and PubMed links in the References section above. Found an error? Contact us.