Thymosin Alpha-1

Quickstart Highlights

Thymosin Alpha-1 (thymalfasin) is a 28-amino-acid acetylated peptide originally isolated from thymic tissue and marketed outside North America as Zadaxin, an immunomodulator approved in more than 35 countries for chronic hepatitis B and C and for chemotherapy-induced immune depression. It is studied for T-cell maturation, Th1 polarization and NK-cell activity. This educational protocol presents the labeled 1.6 mg subcutaneous dose twice weekly, 3–4 days apart, alongside an acute front-load and a daily low-dose community convention, using 2.0 mL bacteriostatic water per 10 mg vial (5 mg/mL) for whole-unit measurements on a U-100 syringe.

• Reconstitute: Add 2 mL bacteriostatic water → 5 mg/mL concentration.
• Dose range: 300 mcg–1.6 mg per injection; 1.6 mg twice weekly (label schedule) or 300–500 mcg once daily (community convention), subcutaneously over an 8–12 week course.
• Easy measuring: At 5 mg/mL, 1 unit = 0.01 mL = 50 mcg on a U-100 insulin syringe.
• Storage: Lyophilized: freeze at −20 °C (−4 °F); after reconstitution, refrigerate at 2–8 °C (35.6–46.4 °F) and use within 28 days.
• Label: The Zadaxin schedule is 1.6 mg twice weekly for 6–12 months (hepatitis indication); the 8–12 week immune-support course, the acute daily front-load and the daily low-dose option are research-community conventions.

Protocol Overview

Concise summary of the twice-weekly regimen.

• Goal: Support immune function through dendritic-cell activation, Th1 polarization and T-cell maturation, with immune effects that persist well beyond the approximately 2-hour plasma half-life.
• Schedule: Subcutaneous injections twice weekly, 3–4 days apart, for 8–12 weeks of immune support; the Zadaxin hepatitis label runs 6–12 months.
• Dose Range: 1.6 mg (1600 mcg) per injection twice weekly on the label schedule; community conventions use 300–500 mcg (0.3–0.5 mg) once daily, or 1.6 mg daily for 3–5 days as an acute front-load.
• Reconstitution: 2 mL per 10 mg vial (5 mg/mL) for accurate unit measurements on standard insulin syringes.
• Storage: Lyophilized frozen at −20 °C (−4 °F); reconstituted refrigerated at 2–8 °C (35.6–46.4 °F); use within 28 days; avoid repeated freeze–thaw cycles.
• Evidence: International prescribing label (Zadaxin) plus human RCTs support the 1.6 mg twice-weekly schedule with high confidence; the daily low-dose option and the 8–12 week immune-support course are community conventions with no human data and low confidence.

Dosing Protocol

Suggested approach based on the Zadaxin prescribing label, human trials and research-community conventions.

• Label schedule (twice weekly, 3–4 days apart): 1.6 mg (1600 mcg) per injection (32 units at 5 mg/mL), the Zadaxin dose of 900 mcg/m² with no titration; the label and trials start at the target dose.
• Acute front-load (daily, 3–5 days): 1.6 mg (1600 mcg) once daily for 3–5 days, then step down to the twice-weekly schedule (research-community convention for acute infection; the hospital sepsis regimens it imitates showed no mortality benefit).
• Daily low-dose convention: 300 mcg (0.3 mg) once daily (6 units), a community-only schedule with no trial data.
• Daily low-dose upper: 500 mcg (0.5 mg) once daily (10 units), the top of the community low-dose range.
• Frequency: Twice weekly on consistent days 3–4 days apart (for example Monday and Thursday); daily dosing applies only to the acute front-load and low-dose conventions.
• Timing: No timing-of-day rule appears in any source; consistency of days is the only convention.
• Cycle: 8–12 weeks for immune support (community convention); the Zadaxin hepatitis label runs 6–12 months, and immune responses continue to improve after a course ends.
• Maintenance: The label specifies no separate maintenance phase; 1.6 mg twice weekly is both the starting and the maintenance dose.

Storage Instructions

Proper storage preserves product quality and efficacy.

• Lyophilized (powder): Refrigerate at 2–8 °C (35.6–46.4 °F) protected from light (the label gives a 24-month shelf life); −20 °C (−4 °F) is acceptable for long-term storage.
• Reconstituted (solution): Refrigerate at 2–8 °C (35.6–46.4 °F), do not freeze, and use within 28 days. The label product is a 1.6 mg single-dose vial dissolved in sterile water and used immediately; the 28-day window is a bacteriostatic-water multi-dose convention, and some sources set it as short as 14 days.
• Allow vials to reach room temperature before opening to minimize condensation uptake.
• Swirl gently to dissolve; do not shake, as agitation can denature the peptide.

Important Notes

Practical considerations for consistency and safety.

• Use new sterile insulin syringes for each injection; dispose in a proper sharps container.
• Rotate injection sites systematically (abdomen, thighs, upper arms) to reduce local irritation and avoid lipohypertrophy.
• Inject slowly and steadily; wait a few seconds before withdrawing the needle to ensure complete delivery.
• Schedule source: The 1.6 mg twice-weekly dose for 6–12 months is the Zadaxin hepatitis label. The 8–12 week immune-support course, the acute daily front-load and the 300–500 mcg daily option are research-community conventions without trial data, and community high-dose schedules of 3–6.4 mg exceed all labeled data.
• Consistency: Keep the same two days each week (for example Monday and Thursday). Immune-marker shifts appear within 3–7 days, adaptive changes in 1–2 weeks, and maximal benefit around 12 weeks.
• Regulatory status: Not approved by Health Canada or the FDA; approved internationally as Zadaxin in more than 35 countries. The FDA removed thymosin alpha-1 from its 503A Category 2 list in September 2024, leaving US compounding status undefined.
• Evidence caveat: Human RCT support is strongest in chronic hepatitis B and COPD exacerbations; a large 2025 sepsis RCT (n=1,106) found no mortality benefit, and immune-support use in healthy adults has not been studied.
• Contraindications: Hypersensitivity to thymalfasin. The label advises against use in deliberately immunosuppressed patients such as transplant recipients unless benefit outweighs risk; sources add active autoimmune disease and pregnancy or breastfeeding.

How This Works

Thymosin alpha-1 is a 28-amino-acid acetylated peptide originally isolated from thymic tissue. It binds Toll-like receptors 2 and 9 on dendritic cells and other antigen-presenting cells, activating MyD88/NF-kB signaling. This drives Th1-type T-cell differentiation, boosts NK-cell cytotoxicity, and raises interferon and IL-2 output, while modulating immune tolerance through indoleamine 2,3-dioxygenase (IDO). Subcutaneous bioavailability is 90–95%, but the plasma half-life is only about 2 hours; the downstream immune changes persist for days, which is why the labeled twice-weekly schedule is effective and why no titration is used. In chronic hepatitis B, a 26-week course produced a 40.6% complete virologic response versus 9.4% in controls, with responses continuing to improve after treatment stopped. A meta-analysis of 39 RCTs supports adjunct use in COPD exacerbations, while a large 2025 sepsis trial (n=1,106) found no mortality benefit, which bounds the evidence to specific indications.

Potential Benefits & Side Effects

Observations from the international label, human RCTs and community reports.

Potential Benefits:

• Immune modulation: dendritic-cell activation via TLR2/TLR9, Th1 polarization, enhanced T-cell maturation and NK-cell activity, and normalization of the CD4/CD8 ratio (human and mechanistic studies).
• Chronic hepatitis B: 40.6% complete virologic response versus 9.4% in controls after a 26-week course in RCT data, with response continuing after treatment stops.
• Adjunct benefit in COPD exacerbations in a meta-analysis of 39 RCTs (n=3,329), and as an immune-support adjuvant during chemotherapy (label indication).
• Community reports of fewer and shorter colds, better energy during illness, and use in Lyme and mold-illness protocols (anecdotal only).
• Immune-marker shifts within 3–7 days, adaptive changes in 1–2 weeks, and maximal benefit around 12 weeks (clinical and community observation).

Potential Side Effects:

• Local injection-site discomfort, erythema or swelling (most common).
• Transient fatigue, mild flu-like symptoms or low-grade fever.
• Rare: rash, transient muscle atrophy, polyarthralgia with hand edema, headache.
• ALT flare during hepatitis B therapy, usually managed with treatment continued.
• Overall adverse-event rates match placebo, with under 1% serious events across 11,000+ patients.
• Avoid in transplant recipients and deliberate immunosuppression, active autoimmune disease, and pregnancy or breastfeeding.

Lifestyle Factors

Complementary strategies for immune resilience during a course.

• Prioritize 7–9 hours of consistent sleep, which supports T-cell and NK-cell function.
• Maintain adequate protein intake and a diet supplying zinc, vitamin D and other micronutrients involved in immune cell development.
• Keep regular moderate exercise; avoid prolonged exhaustive training, which transiently suppresses immune function.
• Manage chronic stress, since sustained cortisol elevation blunts Th1 immunity.
• Limit alcohol and tobacco, both of which impair immune cell function.
• Log injection days and any fatigue or injection-site reactions so that the twice-weekly schedule stays consistent across the 8–12 week course.

Injection Technique

General subcutaneous injection guidance from clinical best-practice resources.

• Clean the vial stopper and chosen skin site with separate alcohol swabs; allow both to dry completely before proceeding.
• Pinch a fold of skin between your fingers; insert the needle at a 45–90° angle into the subcutaneous tissue (fatty layer, not muscle).
• Do not aspirate (pull back the plunger) when giving a subcutaneous injection.
• Inject the solution slowly and steadily; wait at least 6 seconds after injection before withdrawing the needle to ensure complete delivery and minimize leakage.
• Withdraw the needle and apply light pressure with a clean swab; avoid rubbing vigorously.
• Rotate injection sites systematically (abdomen, thighs, upper arms) to prevent lipohypertrophy and maintain consistent absorption.
• Dispose of used syringes and needles immediately in a proper sharps container.

Recommended Source

We recommend Amino Labs for high-purity Thymosin Alpha-1 (10 mg vials).

Note: Product availability and specifications subject to change. Verify current product details on supplier website.

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