Thymosin Alpha-1
Also known as: Ta1, Zadaxin, thymalfasin
At a glance
PeptiGuide dataset · reviewed Aug 2026
What it is
Immune-modulating thymic peptide with human trial evidence and non-US drug approvals.
Status
Clinical Trials
Typical dose
1.6mg
Researched for
Immune support, chronic infections, cancer adjunct
Trial progress
- PrePreclinical
- IPhase I
- IIPhase II
- IIIPhase III
- IVPhase IV
- FDAFDA approved
Phase III - Emerging human evidence with important limitations
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In plain language
Thymosin Alpha-1 is a 28-amino-acid also known as Ta1, Zadaxin, or thymalfasin. The source describes non-US approval as Zadaxin, lack of FDA approval in the United States, and a human-trial evidence base. Reported research areas include immune support, chronic infections, and adjunctive cancer settings. Source-reported dosing centers on 1.6 mg twice weekly by injection, with a community range of 0.8-3.2 mg per dose.
How it's thought to work
Thymosin Alpha-1 is presented as an immune modulator. The supplied evidence describes activity at toll-like receptors, particularly TLR9 and TLR2, on dendritic cells. That pathway is linked in the source to Th1-oriented T-cell signaling, natural killer cell activity, antibody response effects, and regulatory T-cell activity through IDO-associated signaling.
What the research shows
Where the research stands
The source reports a substantial human research base for Thymosin Alpha-1, including use in chronic hepatitis B and safety observations across more than 30 trials with over 11,000 participants. Evidence in sepsis is described as mixed: an earlier ETASS study suggested lower 28-day mortality, while the larger double-blind TESTS phase 3 trial in 1,106 patients did not show a mortality benefit. The source also notes study as an adjunct in selected cancers and vaccine-response contexts, but characterizes that support as weaker.
What it shows
✓ Human studies
Emerging human evidence with important limitations
△ Limitations
Study protocols describe research and are not dosing recommendations.
Bottom line: Approved in 30+ countries as Zadaxin; not FDA approved in the United States; source also reports FDA orphan drug designation and expected Category 1 compounding status return in 2026. Not FDA Approved
Typical dosing
CommunityCommunity dataset1.6 mg
twice weekly
Community-reported dosing context for immune support and chronic infection research; not established here as a treatment recommendation.
Research dosing
Study-specific protocolsHuman trials under way - protocols are study-specific
Timing & administration
Best time to take
Morning
2-3 times per week
Food recommendation
With or without food
Why this timing?
The source associates morning timing with immune-modulating activity and a natural immune rhythm rationale.
Possible side effects
Not everyone experiences these. Individual responses vary with dose, duration, and personal factors.
- Injection site reactions
- Mild fatigue
- Headache
- Rare allergic reactions
- Contraindicated in immunosuppressed transplant patients
- Favorable safety profile
Not everyone experiences side effects, and severity can vary by context, purity, route, and individual health factors.
Sources
Frequently asked questions
Sequence
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One open dataset
Every fact on this page - doses, side effects, references - comes from the same PeptiGuide dataset that powers the Tracker, Compare, and the Lab.
Browse the datasetEducational resource, not medical advice. Talk to your clinician before acting on anything here.
Community discussion
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