Thymosin Alpha-1

low risk

Also: Tα1 · Thymalfasin · Zadaxin

Strong Evidence FDA Approved

Thymosin Alpha-1 is one of the most clinically validated immune peptides. Approved as Zadaxin in 35+ countries for hepatitis B/C and cancer immunotherapy. Meta-analysis of 7 RCTs shows significant mortality reduction in sepsis. Gold standard immune peptide.

Molecular Weight

3108.3 Da

Formula

C129H215N33O55

Common Dosing

1.6 mg SC twice weekly (standard); 3.2 mg/day in acute sepsis protocols

Reported Benefits

Hepatitis B treatment

Strong Evidence 89 studies

Approved in 35 countries. Multiple RCTs: HBV DNA suppression and seroconversion.

Sepsis mortality reduction

Moderate Evidence 28 studies

Meta-analysis (7 RCTs): significant 30-day mortality reduction, especially in immunosuppressed phenotype.

COVID-19 severity reduction

Moderate Evidence 19 studies

Chinese RCT (2021): reduced progression to severe disease and mortality.

Mechanism of Action

Activates dendritic cells, T-helper cells, NK cells; upregulates MHC I/II; increases IL-2 and IFN-γ; modulates Toll-like receptors; thymic T-cell maturation.

Key Clinical Studies

Shrivastava et al. (2022)

Meta-analysis · Meta-analysis (7 RCTs)

PubMed →

Significant reduction in 28-day sepsis mortality (OR 0.50)

Liu et al. (2021)

RCT · n=127

PubMed →

Reduced severe COVID-19 progression and ICU admission

The Immunology Gold Standard

Among all immune-modulating peptides in this database, Thymosin Alpha-1 has the most extensive and credible human evidence. This is the benchmark against which other “immune peptides” should be measured.

Immunosenescence

Growing application in elderly patients with age-related immune decline. Studies suggest partial restoration of thymic output and T-cell diversity — relevant to infection susceptibility and vaccine response in older adults.

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Regulatory Status

FDA Approved

Approved in 35+ countries (Zadaxin). 503A listed for US compounding.

Safety Profile

Side Effects

•Injection site reactions
•Mild fatigue
•Transient flu-like symptoms

Contraindications

•Active autoimmune disease
•Organ transplant on immunosuppression

Drug Interactions

•Immunosuppressants (opposing effects)

Primary Uses

Immune enhancementHepatitis B treatmentSepsis adjunctCancer immunotherapy adjunct

Related Peptides

Thymalin LL-37 TB-500 Vilon

Used For

›Immune Modulation & Infection

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Weekly Briefing

Regulatory updates + new study breakdowns.

› What 2026 FDA Enforcement Signals Mean for the Peptide Compounding Market › FDA Advisory Panel to Review Seven Peptides in July 2026: What Prescribers Need to Know › The Regulatory Status of Research Peptides: A Practitioner's Primer

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Disclaimer: This information is for educational and research purposes only. Not medical advice. Consult a qualified healthcare provider before using any compound.