Thymosin Alpha-1 Guide & Dosage Chart

What is Thymosin Alpha-1?

Thymosin Alpha-1 (Tα1) — sold under the brand name Zadaxin — is a small synthetic peptide made up of 28 amino acids. It is modeled after a hormone naturally produced by the thymus gland, a small organ in the chest that plays a central role in building and training your immune system.^[6] In plain terms, think of the thymus as a boot camp for immune cells. Thymosin Alpha-1 is one of the key signals that boot camp uses to train soldiers (T cells) for action.

The peptide was first isolated from a mixture of thymic proteins called thymosin fraction 5.^[4] Today's research-grade Thymosin Alpha-1 is fully synthetic, meaning it is built in a lab rather than extracted from animal tissue.^[1]

How Thymosin Alpha-1 Works

Here is a simple way to picture it: your immune system is like an army. T cells are the specialized soldiers. As we age, the thymus gland shrinks — a process called thymic involution — and fewer soldiers get properly trained.^[2] Thymosin Alpha-1 acts like a drill sergeant signal that helps coax immature immune cells (called thymocytes) to grow up, differentiate, and become active T cells ready to fight.^[1]

Beyond T cells, research suggests Thymosin Alpha-1 also activates dendritic cells (scouts that spot threats) and macrophages (cleanup crew), and helps regulate the mix of chemical signals — called cytokines and chemokines — that coordinate immune responses.^[5] Importantly, it appears to modulate rather than simply amplify the immune system. Some research has explored whether it can calm an overactive immune response, such as the dangerous T-cell over-activation seen in severe viral illness, as well as stimulate an underactive one.^[6]

What the Research Shows

Hepatitis B

Several clinical trials have tested Thymosin Alpha-1 in patients with chronic hepatitis B (CHB). A randomized controlled trial found that HBV DNA clearance — a key marker of viral suppression — occurred in roughly 40% of patients treated with Tα1 for six months, compared with only about 9% in untreated controls.^[1] A review of both English and Chinese literature concluded that Tα1 monotherapy suppresses viral replication better than no treatment, and that combination therapy with standard antivirals showed even stronger results on viral DNA suppression and immune conversion markers.^[3]

Hepatitis C

In hepatitis C trials, the combination of Thymosin Alpha-1 plus interferon alfa-2b outperformed interferon alone. One trial reported normal liver enzyme levels (ALT) in 71% of combination patients versus 35% on interferon alone, and viral RNA clearance in 65% versus 29%.^[1] Results across trials were mixed, so researchers continue to study which patients benefit most.^[1]

Vaccine Response and Aging

Older adults and people with weakened immune systems often respond poorly to vaccines. Research has explored whether Thymosin Alpha-1 can boost the immune response to influenza vaccination in at-risk groups, including elderly patients and those on hemodialysis.^[5] The peptide appears to enhance T-cell, dendritic cell, and antibody responses to the vaccine.^[5] Studies also suggest it may help counteract immunosenescence — the gradual wearing-down of immune function that comes with age — by stimulating thymic output and reducing chronic low-grade inflammation.^[2]

Other Areas of Investigation

Researchers have also investigated Thymosin Alpha-1 in malignant melanoma, hepatocellular carcinoma, drug-resistant tuberculosis, DiGeorge's syndrome (a condition involving thymus underdevelopment), and sepsis.^[1][6] Its antibacterial and antiviral properties have led to interest in a range of infectious disease contexts.^[6]

What Thymosin Alpha-1 Is Being Studied For

• Chronic hepatitis B and C (as monotherapy and in combination with antivirals)^[1][3]
• Enhancing influenza vaccine immunogenicity in elderly and immunocompromised individuals^[5]
• Age-related immune decline (immunosenescence)^[2]
• Sepsis and severe infections^[6]
• Cancers including melanoma and hepatocellular carcinoma^[1]
• DiGeorge's syndrome and other T-cell deficiency states^[1]

How Thymosin Alpha-1 Is Dosed in Research

Dosing in published trials varies by condition and study design. The dosage chart on this page summarizes the key figures — for example, hepatitis B and C trials used 1.6 mg administered subcutaneously twice weekly, while influenza vaccine studies in hemodialysis patients used higher amounts in the 3.2–6.4 mg range per trial protocol.^[1][5] These are research-derived figures, not clinical recommendations. Use the calculator on this page to work through volume and concentration math for any given vial. Thymosin Alpha-1 is given by subcutaneous injection (under the skin) in all major trials reviewed.^[1] Its half-life is approximately two hours, with blood levels returning to baseline within 24 hours after dosing.^[1]

Mixing and Storing Thymosin Alpha-1

Research-grade Thymosin Alpha-1 typically comes as a lyophilized powder (freeze-dried) in a sealed vial. To reconstitute it, bacteriostatic water (sterile water containing a small amount of benzyl alcohol as a preservative) is drawn up in a syringe and injected slowly down the side of the vial — not directly onto the powder. Swirl gently; do not shake. Once reconstituted, store the vial in the refrigerator (2–8 °C / 36–46 °F) and protect it from light. Use reconstituted solution within the timeframe specified by the manufacturer, typically 7–28 days depending on the preservative used. Lyophilized (unmixed) vials should be kept frozen or refrigerated until use. Always check your specific product's instructions and handle all research compounds under appropriate laboratory conditions.

Sources

1. Thymosin alpha-1. — American journal of health-system pharmacy : AJHP : official journal of the American Society of Health-System Pharmacists, 2001. PMID 11381492.
2. Aging and Thymosin Alpha-1. — International journal of molecular sciences, 2025. PMID 41373628.
3. Thymosin alpha-1 treatment in chronic hepatitis B. — Expert opinion on biological therapy, 2015. PMID 25640173.
4. beta-Thymosins. — Annals of the New York Academy of Sciences, 2007. PMID 17468232.
5. Utility of thymosin alpha-1 (Zadaxin) as a co-adjuvant in influenza vaccines: a review. — Journal of preventive medicine and hygiene, 2011. PMID 22010537.
6. Thymosin alpha 1: A comprehensive review of the literature. — World journal of virology, 2020. PMID 33362999.