Thymosin Alpha-1
Tα1 · Zadaxin · Thymalfasin
Thymosin α1 (thymalfasin, Tα1) is a 28-amino-acid thymic peptide. Branded Zadaxin is a prescription medicine in 30+ countries, mainly for chronic hepatitis B and as an immune adjuvant. It is not FDA-approved in the United States; orphan designations are not an NDA. US research-chem and compounded vials are not that branded product. This leaf is immune biology, not a hepatitis, cancer, sepsis, or Lyme treatment page.
Use-case scores
0–10 against the evidence we have, not a gym ranking. Hidden domains do not apply here.
- Immune7.5/10
Branded thymalfasin has human RCTs and marketing authorization in 30+ countries. Ceiling 9 for approved indication; haircut because a US research vial is not Zadaxin and this site will not score a hepatitis treatment claim.
- Longevity / aging4/10
Immunosenescence is the aging conversation. That is not a longevity RCT of gray-market Tα1. Community / small-human ceiling after the haircut.
Compound card
- Sequence
- Ac-SDAAVDTSSEITTKDLKEKKEVVEEAEN (28 aa)
- Class
- Thymic peptide / thymalfasin (Zadaxin is the branded drug abroad)
- Formula
- C129H215N33O55
- Status
- Not FDA-approved · research use
Patient Suitability
✓ Best For
- Need the 28-mer immune peptideThis is thymalfasin class. Confirm you did not want Tβ4 or Thymalin.
- Comparing a US vial to ZadaxinUse this page to keep those identities apart.
✗ Avoid If
- Organ transplant on immunosuppressants unless the prescriber owns it
- Active autoimmune flare unless the prescriber owns it
- Pregnancy
- Using it as a Lyme or cancer protocol from a forum
! Use With Caution If
- Any autoimmune history
- Checkpoint-inhibitor therapy (theoretically additive immune activation)
- Unverified research-chem identity
How it works
Thymosin α1 (thymalfasin, Tα1) is a 28-residue N-acetylated peptide originally isolated from thymic extracts by Allan Goldstein. Branded Zadaxin is a prescription medicine in 30+ countries, mainly chronic hepatitis B and as an immune adjuvant. That is a real drug program. It is not an FDA-approved US product. Orphan designations (hepatitis B 1991, hepatitis C 1995, among others) are not an NDA. A research-chem or compounded US vial is not interchangeable with SciClone Zadaxin on paper.
Mechanistically it sits on innate-to-adaptive signaling: TLR2/TLR9 on dendritic cells, T-cell maturation, NK cytotoxicity, a Th1-leaning cytokine tilt in the papers that measured it. Romani 2012 is the honest “pleiotropy” review: lots of immune biology, not a single receptor drug. This catalog files it under recovery. Score it as immune. It is not BPC-157, not TB-500, and not a Lyme protocol.
Source: PMID: 17316418
Orphan designation is not FDA approval
Zadaxin is a medicine in 30+ countries. In the US, thymalfasin has orphan designations and no NDA. Do not tell a reader their research vial is FDA-approved.
Goal context
Immune competence, not a named infection
The honest job is T-cell/NK signaling. Branded labels abroad are hepatitis B and adjuvant use. A diagnosis belongs with a clinician and a labeled product, not 1.6 mg from a forum calendar.
US vial vs Zadaxin
Same 28-mer class. Different factory, label, and safety database. Compounded 503A material (when legal) is still not an NDA. Research-chem is weaker still.
Background & History
Thymosin α1 (thymalfasin) is a 28-aa thymic peptide. Zadaxin is a prescription medicine in 30+ countries, mainly chronic hepatitis B and as an immune adjuvant. It is not FDA-approved in the United States; orphan designations are not an NDA. US research-chem and compounded vials are not branded Zadaxin. Score it as immune, not as a hepatitis/cancer/Lyme treatment page.
Research Use Cases
- ✓Defined 28-mer immune peptide identity (vs Tβ4 and Thymalin)
- ✓Comparing a US vial to ex-US Zadaxin (they are not interchangeable on paper)
- ✓Not a DIY viral-hepatitis, oncology, sepsis, or Lyme protocol
Dosing
| Phase | Dose | Frequency | Notes |
|---|---|---|---|
| Branded schedule (ex-US Zadaxin, clinician-directed) | 1.6 mg | Twice weekly SubQ | Common labeled cadence. Not a DIY hepatitis course. |
| US research-chem (unlabeled) | 1.6 mg | Twice weekly SubQ (copied from the label) | Copied number, not a US label. Confirm fill and sterility. Not a disease protocol. |
When to increase
- A clinician who can prescribe a real product is directing it
When to decrease
- Injection-site or flu-like effects that are not settling
- A clinician is directing a stop
Administration
Preparation
- Bacteriostatic water (BAC water)
- Insulin syringes (29-31 gauge)
- Alcohol swabs
Storage
Reconstitution
| Vial | Water | Concentration | Example dose |
|---|---|---|---|
| 5 mg | 1.0 mL BAC | 5 mg/mL | 1.6 mg = 0.32 mL = 32 units on a U-100 syringe |
| 10 mg | 2.0 mL BAC | 5 mg/mL | 1.6 mg = 0.32 mL = 32 units on a U-100 syringe |
Change vial size or water volume? Open the reconstitution calculator.
Safety & Considerations
Where Zadaxin is a labeled medicine, injection-site reactions are the common complaint and the branded safety file is larger than most research peptides. That file does not automatically transfer to an unlabeled US vial. Do not treat hepatitis, cancer, sepsis, or Lyme on this page. Transplant immunosuppression and active autoimmunity are reasons to stay out unless a physician who knows the labeled product is running it. Sterile reconstitution still matters.
Regulatory & Legal Status
Approved in 37+ countries (including Italy, China) as Zadaxin®; not FDA-approved in the US
Competitive athletes subject to anti-doping controls should not use Thymosin Alpha-1.
Research Chemical
US Compounding: Not eligible / not available
⚠️ This information is for educational purposes only and may not reflect the most current regulatory updates. Always verify with official FDA, WADA, and jurisdiction-specific sources before use.
Limits of current evidence
- Not FDA-approved. Orphan designation ≠ NDA. SciClone did not complete a US hepatitis NDA that met FDA’s bar.
- Ex-US RCTs and labels are branded thymalfasin. They do not automatically describe a research-chem cake.
- This page will not convert adjuvant oncology, sepsis, or Lyme papers into a consumer protocol.
- Category / compounding status in the US has moved. Check the regulatory panel; do not freeze a 2023 Category 2 sentence as eternal law without reading the current list.
Verdict
Tα1 is one of the few catalog peptides that is a real drug somewhere. Use the branded product under a clinician if the job is a labeled indication. Use this leaf to stop calling a US research vial “FDA-approved Zadaxin” and to stop treating hepatitis, cancer, sepsis, or Lyme from a reconstitution calculator.
Interactions & Contraindications
Branded thymalfasin has a larger safety file than gray-market cakes; that file does not automatically transfer. Checkpoint inhibitors: theoretically additive immune activation. Immunosuppressants: opposing job. Transplant and active autoimmunity belong with a prescriber.
Synergies & Common Stacks
Thymalin is a Khavinson thymic extract. Tα1 is a defined 28-mer. Same organ story, different material. Not a synergy RCT.
Thymosin Alpha-1 vs. TB-500
Canonical comparison: Thymosin Alpha-1 vs TB-500
| Attribute | Thymosin Alpha-1 | TB-500 |
|---|---|---|
| Mechanism | Immune modulation + thymic activation | Actin polymerization + cell migration |
| Primary Use | Immune support, infection, cancer adjuvant | Physical tissue healing, injury recovery |
| Evidence Quality | Human trials (37+ country approval) | Primarily preclinical |
| WADA Status | Prohibited (S4) | Prohibited (S0) |
| Dose Frequency | 900 mcg – 1.6 mg 2× weekly | 2–5 mg 2× weekly |
Verdict: Thymosin Alpha-1 targets immunity; TB-500 targets tissue healing. These peptides address completely different goals with minimal overlap - they are not competing options but complementary tools.
Appears in goal guides
Goal guides are maps, not clinic protocols. A mention here is not a treatment plan.
Immune Resilience & Post-Viral Stack
Thymosin α1 and Thymalin identity. Zadaxin is not a US NDA. This is not a viral-pathogenesis or thymic-regeneration treatment page.
Immune Optimization Protocol
Thymic cytomax (Vladonix) plus Endoluten and Bonomarlot, then Thymosin Alpha-1 and Selank, with LL-37/KPV as acute experimental tools.
What to Expect
Weeks 1-2
- Injection-site reactions
- Possible flu-like feel
- Nothing dramatic is the usual report
- This is not a viral-load protocol. Keep the schedule or stop with a clinician.
Weeks 3-4
- Tolerance at the site often improves
- No honest consumer immune-lab schedule for a research vial
- Branded courses abroad are long. That is not a research-chem mandate.
Weeks 5-6+
- Still not a hepatitis or oncology endpoint
- Stop or continue only with a prescriber who can use a real product
Frequently Asked Questions
Is thymosin α1 FDA-approved?▼
Is a research vial the same as Zadaxin?▼
What is the usual labeled dose abroad?▼
How do I reconstitute a 5 mg vial?▼
Does it treat hepatitis B or C?▼
Cancer, sepsis, Lyme, Long COVID?▼
How is this different from thymosin β4 / TB-500?▼
How is this different from Thymalin?▼
WADA / sport?▼
Storage?▼
References
- Garaci E, Pica F, Matteucci C “"Historical review on thymosin α1 in oncology".” Expert Opin Biol Ther (2015). PMID: 26096345
- Romani L, Moretti S, Fallarino F “"Jack of all trades: thymosin α1 and its pleiotropy".” Ann N Y Acad Sci (2012). PMID: 23045964
- Chen JF, Chen SR, Lei ZY “"Safety and efficacy of Thymosin α1 in the treatment of hepatitis B...".” Front Immunol (2022). PMID: 35616850
- Ancell CD, Phipps J, Young L “"Thymosin alpha-1 (Review)".” Am J Health Syst Pharm (2001). PMID: 11381492
- Tuthill C, et al. “Thymosin alpha 1: a comprehensive review of the literature.” Ann N Y Acad Sci (2010). PMID: 20633111
- Matteucci C, et al. “Thymalfasin (thymosin-α1) in the prevention of severe infections in immunocompromised patients.” Ann N Y Acad Sci (2017). PMID: 28493411
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