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The Peptide Effect
Dosage Guide

Thymosin Alpha-1 Dosage Guide: Immune Protocol

Educational reference covering thymosin alpha-1 (thymalfasin/Zadaxin) dosage protocols, immune support applications, and administration guidelines as discussed in peer-reviewed research literature. For informational purposes only.

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Medical Disclaimer

This guide is for educational and informational purposes only. It is not medical advice. Dosages described reflect ranges discussed in published research and clinical practice literature — they are not recommendations. Always consult a licensed healthcare provider before using any peptide. Legality and availability vary by jurisdiction.

Overview

Thymosin alpha-1 (Ta1) is a 28-amino-acid peptide originally isolated from thymic tissue by Allan Goldstein at the George Washington University in the 1970s. It plays a central role in immune system maturation by promoting T-cell differentiation and function. The synthetic version, known as thymalfasin, has been marketed under the brand name Zadaxin and has received regulatory approval in over 35 countries for indications including hepatitis B, hepatitis C, and as an immune adjuvant in vaccine protocols. The FDA granted orphan drug designation for thymosin alpha-1 in the treatment of hepatitis B and DiGeorge syndrome. In research literature, thymosin alpha-1 has been discussed for its effects on both innate and adaptive immunity, including activation of dendritic cells, enhancement of T-helper 1 (Th1) responses, and modulation of Toll-like receptor signaling pathways.

Dosing Protocols

Standard Immune Support Protocol

Route: Subcutaneous injection
Dose: 1.6 mg
Frequency: Twice weekly (e.g., Monday and Thursday)
Duration: Ongoing or as clinically indicated

This is the most widely discussed dosing regimen in clinical literature and corresponds to the approved Zadaxin dosing schedule used in hepatitis B/C treatment studies. The 1.6 mg dose was established in early clinical trials and has been the standard reference dose in most published research.

Acute Immune Support Protocol

Route: Subcutaneous injection
Dose: 1.6 mg
Frequency: Once daily
Duration: 7–14 days

An intensified dosing schedule discussed in the context of acute immune challenges. Daily dosing for short periods has been referenced in some clinical trial designs and case reports involving severe infections. After the acute phase, protocols typically transition to the standard twice-weekly schedule.

Chronic Infection / Adjuvant Protocol

Route: Subcutaneous injection
Dose: 1.6 mg
Frequency: Twice weekly
Duration: 6–12 months

Extended treatment courses have been discussed in the context of chronic hepatitis B and C management. In pivotal clinical trials, thymosin alpha-1 was administered for 6–12 months in combination with interferon-alpha. Long-term safety data from these trials support the tolerability of extended use at this dose.

Reconstitution & Storage

Vial sizes1.6 mg lyophilized powder per vial (Zadaxin standard)
Recommended water volume1 mL sterile water for injection per vial, yielding 1.6 mg/mL
StorageStore unreconstituted vials at room temperature (15–30 °C / 59–86 °F). Do not freeze.
Stability once reconstitutedReconstituted solution should be used immediately or within a few hours. Thymosin alpha-1 is provided as individual-dose vials designed for single use. Do not store reconstituted solution.

Use our reconstitution calculator to determine exact syringe units for your dose.

Cycle Guidance

In clinical trial settings, thymosin alpha-1 has been administered continuously at 1.6 mg twice weekly for periods of 6–12 months without reported loss of efficacy or significant safety concerns. The published literature does not emphasize a need for cycling in the traditional sense. However, in wellness and longevity contexts outside of specific disease treatment, some practitioners discuss periodic courses of 2–3 months with reassessment intervals. The decision to continue, pause, or adjust dosing is generally made based on immune markers (such as lymphocyte subsets and cytokine profiles) and clinical response. For vaccine adjuvant use, thymosin alpha-1 has been administered as short courses around the vaccination schedule.

Stacking Considerations

  • Thymosin alpha-1 has been studied in combination with interferon-alpha for hepatitis B and C treatment, with several trials reporting improved virological response rates compared to interferon alone.
  • Combination with epithalon has been discussed in immunosenescence and longevity contexts, as both peptides target different aspects of immune aging, though controlled data on this combination is not available.
  • Some practitioners discuss combining thymosin alpha-1 with thymosin beta-4 (TB-500), noting that they have distinct mechanisms — alpha-1 primarily modulates adaptive immunity while beta-4 is associated with tissue repair and wound healing.
  • Concurrent use with immunosuppressive medications requires careful consideration, as thymosin alpha-1's immune-enhancing properties could theoretically counteract immunosuppressive therapy.

Potential Side Effects

  • Injection site reactions (erythema, discomfort) — reported in clinical trials but generally mild and transient
  • Fatigue — reported infrequently in clinical study participants
  • Myalgia (muscle discomfort) — reported at low frequency in published studies
  • Low-grade fever — occasionally reported, potentially reflecting immune activation
  • Nausea — reported rarely in clinical trials
  • The overall safety profile in published clinical trials has been favorable, with adverse event rates generally comparable to placebo in controlled studies

Contraindications & Cautions

  • Known hypersensitivity to thymosin alpha-1 or any component of the formulation
  • Organ transplant recipients on immunosuppressive therapy — immune stimulation could increase rejection risk
  • Active autoimmune disease — enhancing immune function may exacerbate autoimmune conditions
  • Pregnancy and breastfeeding — insufficient safety data in these populations
  • Concurrent use with immunosuppressive medications requires careful risk-benefit assessment

Related

Thymosin Alpha-1 Profileimmune systeminflammationlongevityepithalon dosagekpv dosage

References

  1. Thymosin alpha 1: a comprehensive review of the literature (2007) — PubMed
  2. The clinical development of thymosin alpha 1 for the treatment of cancer and chronic hepatitis (2010) — PubMed
  3. Thymosin alpha1 activates dendritic cell tryptophan catabolism and establishes a regulatory environment for balance of inflammation and tolerance (2006) — PubMed
  4. Thymosin alpha 1 — a peptide immune modulator with a broad spectrum of clinical applications (2010) — PubMed

Frequently Asked Questions

What is the standard thymosin alpha-1 dosage?
The standard dosage discussed in the majority of clinical literature is 1.6 mg administered subcutaneously twice weekly. This dosing regimen was used in the pivotal clinical trials that led to the approval of thymalfasin (Zadaxin) in multiple countries for hepatitis B and C treatment. The 1.6 mg dose corresponds to the content of one standard Zadaxin vial.
Is thymosin alpha-1 FDA-approved?
Thymosin alpha-1 (as thymalfasin/Zadaxin) has not received full FDA approval in the United States, but it has been granted FDA orphan drug designation for hepatitis B and DiGeorge syndrome. It is approved in over 35 countries worldwide, particularly in Asia, South America, and parts of Europe, for indications including chronic hepatitis B, hepatitis C (as an adjunct), and as an immune system modifier.
How long does thymosin alpha-1 take to show immune effects?
In clinical studies, changes in immune parameters such as T-cell subset ratios and cytokine profiles have been reported within weeks of initiating treatment. However, clinical outcomes in hepatitis trials were typically assessed at 6–12 months. The timeline for immune modulation may vary depending on the individual's baseline immune status and the specific condition being addressed.
Can thymosin alpha-1 be used alongside vaccines?
Thymosin alpha-1 has been studied as a vaccine adjuvant in several published trials, including influenza and hepatitis B vaccination studies. Research has reported enhanced antibody responses and improved seroconversion rates when thymosin alpha-1 was administered alongside vaccines, particularly in immunocompromised or elderly populations who typically mount weaker vaccine responses. Short courses around the vaccination schedule have been the most commonly discussed approach.
What is the difference between thymosin alpha-1 and thymosin beta-4?
Despite sharing the thymosin name, these are distinct peptides with different structures and functions. Thymosin alpha-1 is a 28-amino-acid peptide primarily associated with immune modulation, T-cell maturation, and dendritic cell activation. Thymosin beta-4 (TB-500) is a 43-amino-acid peptide primarily discussed in the context of tissue repair, wound healing, and anti-inflammatory effects. They were both originally isolated from thymic tissue but act through different mechanisms and receptors.
Does thymosin alpha-1 require reconstitution?
Yes, thymosin alpha-1 is supplied as a lyophilized (freeze-dried) powder that must be reconstituted with sterile water for injection before administration. The standard Zadaxin vial contains 1.6 mg of lyophilized thymalfasin, which is reconstituted with 1 mL of the provided diluent. Unlike some other peptides, the reconstituted solution is intended for immediate single use and should not be stored.