Thymosin Alpha 1
Synthetic Thymic Hormone | Immune System Modulation
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What is Thymosin Alpha 1?
Thymosin Alpha 1 is a lab-made 28-amino-acid peptide identical to a natural thymus-gland hormone, and it's the basis of an immune-focused medication approved in many countries outside the US. Researchers study it extensively for its effects on immune-cell signaling in clinical trials. Research-grade material sold here is intended for laboratory research use only, not for human use.
Key terms:
Thymosin Alpha 1 is a synthetic acetylated polypeptide.
Thymosin Alpha 1 (Ta1, also sold as Thymalfasin or Zadaxin) is a lab-made peptide of 28 amino acids. It is identical to a hormone the thymus gland makes naturally. More than 30 clinical trials have studied it in over 11,000 patients. It holds FDA orphan drug designations for four conditions and is approved in more than 35 countries. Across those trials, serious adverse events were reported in under 1% of patients. Researchers describe broad effects on immune system signaling.
Key research areas
- Primary FDA-studied route with extensive clinical data
- Maximum immune modulation through systemic circulation
- Established dosing protocols from 35+ countries of clinical use
Researched dosing
This table reflects the dosing schedules used in published clinical research on Thymosin Alpha 1, presented as research methodology, not personal usage guidance.
| Phase | Dose | Frequency | Route |
|---|---|---|---|
| Standard immune studies | 1.6mg | 2x weekly | SubQ |
| Acute-condition studies (sepsis) | 1.6mg | 2x daily x 5 days, then daily | SubQ or IM |
| Cancer and hepatitis studies | 1.6mg | 2x weekly | SubQ |
| Maintenance | 1.6mg | 2x weekly | SubQ |
Commonly cycled 24 weeks on, 0+ weeks off.
How it works
At the cell level, Thymosin Alpha 1 research looks at how the peptide activates several immune-signaling pathways (TLR receptors) to help immune cells mature and respond — the terms below just name those cell-signaling steps.
Injectable Ta1 provides optimal bioavailability (90-95%) with rapid Tmax of 2 hours. Activates multiple TLR pathways, enhances T-cell maturation, stimulates NK cells, and modulates dendritic cell function through systemic circulation.
Molecular data
These figures — molecular weight, sequence, chain length — are the chemistry ID researchers use to confirm a Thymosin Alpha 1 sample's identity, at 28 amino acids one of the larger peptides in this encyclopedia.
- Weight
- 3108 Da
- Length
- 28 amino acids
- Type
- Acetylated polypeptide
Ac-Ser-Asp-Ala-Ala-Val-Asp-Thr-Ser-Ser-Glu-Ile-Thr-Thr-Lys-Asp-Leu-Lys-Glu-Lys-Lys-Glu-Val-Val-Glu-Glu-Ala-Glu-Asn-OH
Pharmacokinetics
This chart shows how quickly a research dose of Thymosin Alpha 1 is absorbed and cleared in clinical studies — read it like a timer: the peak is when levels are highest, then the curve trails off as the compound clears.
- Peak
- 2 hr
- Half-life
- 2 hrs
- Cleared
- ~10 hrs
Zadaxin prescribing information
Research applications
This section lists the research areas — immune function, inflammation, and recovery support among them — that clinical trials have studied for Thymosin Alpha 1 worldwide, a summary of what's been published in the literature, not medical claims about people.
Immunity
FDA orphan drug designation for DiGeorge syndrome with documented restoration of T-cell function and immune competence in clinical trials. Enhances immunogenicity in elderly and hemodialysis patients with improved antibody responses to H1N1 and COVID-19 vaccines. Restores CD4+ T-cell counts and reduces opportunistic infections in HIV patients with sustained immunological improvement.
Inflammation
Clinical study showed significant reduction in pro-inflammatory cytokines including TNF-α, IL-1β, and IL-6 while maintaining balanced immune responses. Demonstrated ability to restore immune homeostasis in lymphocytes during post-acute sequelae of SARS-CoV-2 infection.
Recovery
Supports immune recovery in cancer and hepatitis patients undergoing treatment. Reduces opportunistic infections and supports immune competence during recovery.
Longevity
Thymic hormone replacement supporting age-related immune decline and immune senescence through T-cell maturation and NK cell stimulation.
Cellular
Modulates dendritic cell function and activates multiple TLR pathways for comprehensive cellular immune responses.
Dosage reference
- Doses used in research
- 1.6 mg
- Frequency in studies
- 2x weekly
- Handling
- Reconstituted solution — research use only; not for administration
- Timeline reported in studies
- 2-4 weeks for immune effects, 6-12 weeks maximum
- Storage
- Lyophilized: -18°C, Reconstituted: 2-8°C up to 7 days
- Cycle length
- 6 months standard
- Break between cycles
- As directed by physician
Interactions
This list shows which other immune-modulating compounds and treatments researchers have studied alongside Thymosin Alpha 1, and why.
Reconstitution & storage
This is the standard laboratory method for turning freeze-dried Thymosin Alpha 1 powder into a liquid research solution — the same basic water-based mixing process used for most peptide research.
- Clean work area and hands thoroughly
- Add 1.0 mL sterile water slowly to lyophilized powder
- Inject water slowly down vial side (not directly onto powder)
- Gently swirl until completely dissolved (never shake)
- Final concentration: 1.6 mg/mL
- Store the reconstituted solution refrigerated (2–8°C), labeled with the date and concentration, for laboratory research use only.
Lyophilized: -18°C, use within As per manufacturer expiry
Reconstituted: 2-8°C, use within Up to 7 days
Open the Thymosin Alpha 1 reconstitution calculatorQuality indicators
These are the visual and lab-report checks researchers use to confirm a Thymosin Alpha 1 sample is pure and correctly identified before it goes into a study.
White Lyophilized Powder - Properly freeze-dried Ta1 appears as white, fluffy powder that fills most of vial bottom. Professional pharmaceutical packaging.
Clear Solution After Reconstitution - When mixed with sterile water, solution should be crystal clear with no particles, cloudiness, or precipitation.
Proper Pharmaceutical Labeling - Vials should have clear labeling with batch numbers, expiration dates, and 1.6mg dosage clearly marked.
Minor Powder Compaction - Slight compaction during shipping is acceptable if powder dissolves completely with gentle mixing.
Discolored or Collapsed Powder - Yellow, brown, or collapsed powder indicates degradation from heat exposure or moisture damage.
Persistent Cloudiness - Solution remains cloudy, contains particles, or shows precipitation after reconstitution - indicates degraded product.
What to expect
This timeline summarizes what the clinical research literature reports at each stage of a study — research context for comparing studies, not a personal-results promise.
Initial immune system activation
Enhanced immune function and reduced infection risk
Maximum immunomodulatory benefits
Sustained immune support with continued use
Safety notes
This section covers how Thymosin Alpha 1 is regulated and handled — its regulatory status varies by country, and this reflects handling and monitoring notes drawn from the clinical literature, not medical guidance.
- Contraindicated in organ transplant recipients (risk of graft rejection)
- Monitor for hypersensitivity reactions with first dose
- Not recommended during pregnancy or breastfeeding
- FDA orphan drug designation for four conditions
- Approved in 35+ countries worldwide (Zadaxin/Thymalfasin)
- Exceptional safety profile with <1% serious adverse events across 11,000+ patients
Regulatory status
- Not approved by the FDA for any indication.
- Supplied and described for laboratory research use only — not for human or veterinary use.
Community data
Community Insights
Based on data the community reported. Not clinical proof.
References
Comprehensive review across 11,000+ patients in 30+ clinical trials showing <1% serious adverse events, establishing excellent long-term safety profile for potential clinical applications.
Study demonstrating Ta1's ability to restore immune homeostasis in lymphocytes during post-acute sequelae of SARS-CoV-2 infection with normalized T-cell populations and reduced inflammatory markers.
Clinical study showing significant reduction in pro-inflammatory cytokines including TNF-α, IL-1β, and IL-6 while maintaining balanced immune responses in coronavirus disease patients.