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Thymosin Alpha-1

Tα1 / Zadaxin

Category · For RecoveryStatus · COMPCitations · 60

The verdict

Yes for documented hepatitis B/C or oncology-adjunct use under specialist care — depends/no for healthy-adult immune-support use.

By source — cost, legality, risk

Brand
Not available in US
None in US — Zadaxin approved abroad in 35+ countries
No FDA-approved Tα1; Zadaxin is import-only and not legally available to US patients.
Compounded 503A pharmacy
$180–$400/mo where still sold
Rx · status contested post Dec 2024 reclassification
Mid. Compounders shipping Tα1 vary in legal posture; some pharmacies pulled it.
RUO research peptide
$80–$200/mo
Sold 'for research only'
Highest. The dominant US supply path. Synthesis is well-established but identity by mass spec is the only honest check.
Gray-market raw
Suspended — not currently shipping via user's vendor
Unregulated overseas import
User's primary gray vendor marked Tα1 SUSPENDED in 2026 list; available via other overseas raws but supply is intermittent.

Stop signals · abort if

Sources · top 5 of 60

01Ancell CD, et al. Thymosin alpha-1. American journal of health-system pharmacy : AJHP : official journal of the American Society of Health-System Pharmacists. 2001;58(10):879-85; quiz 886-8. PMID: 11381492.
02Wu J, et al. The efficacy and safety of thymosin α1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial. BMJ (Clinical research ed.). 2025;388:e082583. PMID: 39814420.
03Simonova MA, et al. Aging and Thymosin Alpha-1. International journal of molecular sciences. 2025;26(23). PMID: 41373628.
04Shehadeh F, et al. A Pilot Trial of Thymalfasin (Thymosin-α-1) to Treat Hospitalized Patients With Hypoxemia and Lymphocytopenia Due to Coronavirus Disease 2019 Infection. The Journal of infectious diseases. 2023;227(2):226-235. PMID: 36056913.
05Wu X, et al. Thymosin alpha-1 treatment in chronic hepatitis B. Expert opinion on biological therapy. 2015;15 Suppl 1:S129-32. PMID: 25640173.