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Peptides / Thymosin alpha-1 / United States

Thymosin alpha-1 in the United States

Legal status, what it is, and the listed suppliers in the United States that list it.

Legal status in the United States

Not an approved medicine. The openFDA drug label database holds no current label for thymalfasin (checked 2026-09-22).

As understood at 2026-09-22. Verify with the FDA.

What Thymosin alpha-1 is

Thymosin alpha-1 is a 28-amino-acid peptide originally isolated from thymus tissue, the gland where T cells mature. The synthetic form is called thymalfasin. It has been through a large clinical programme as an immune modulator, mostly outside the UK, US and Australia, and is not an approved medicine in any of the three.

Full Thymosin alpha-1 page: targets and research →

Listed suppliers in the United States

8 of the 10 suppliers we list in the United States list Thymosin alpha-1. Listed, not endorsed: each row is the supplier’s own stated terms.

BioLongevity Labs United States All products are manufactured for research use only. Research Use Only products sold here are intended solely for laboratory research. Core Peptides United States Products are for laboratory, research or analytical purposes only, and are not for human consumption. Direct Peptides United States All products are sold strictly for laboratory research use only and are not for human or animal consumption. Direct Peptides is a chemical supplier, not a compounding pharmacy or 503A/503B facility. Licensed Peptides United States Supplied strictly for laboratory research use only. Not intended for human consumption, veterinary use, therapeutic applications, or diagnostic use. No dosing instructions are provided. Nationwide Peptides United States For Research Use Only. Products are not intended for human or animal consumption, ingestion, injection, or any form of administration. Peak Lab Peptides United States All products on this site are for research and development use only. Products are not for human consumption of any kind. Protide Health United States All products are supplied for laboratory research only and are not for human or animal consumption, medical use, veterinary use, or any therapeutic, diagnostic, or clinical purpose. Sigma Compounds United States Products are for research and development purposes only and are not for human consumption.

Clinical Research

The efficacy and safety of thymosin alpha1 for sepsis (TESTS): multicentre, double blinded, randomised, placebo controlled, phase 3 trial
Wu J, Pei F, Zhou L, et al. (2025). BMJ. human 1,106 adults with sepsis across 22 centres in China; phase 3, double-blind, placebo-controlled
A Pilot Trial of Thymalfasin (Thymosin-alpha-1) to Treat Hospitalized Patients With Hypoxemia and Lymphocytopenia Due to Coronavirus Disease 2019 Infection
Shehadeh F, Benitez G, Mylona EK, et al. (2023). The Journal of Infectious Diseases. human 49 hospitalised patients with COVID-19, low oxygen levels and low lymphocyte counts; open-label, randomised against standard care
The efficacy of thymosin alpha-1 therapy in moderate to critical COVID-19 patients: a systematic review, meta-analysis, and meta-regression
Soeroto AY, Suryadinata H, Yanto TA, Hariyanto TI (2023). Inflammopharmacology. meta-analysis n/a (pooled analysis of 8 studies in moderate to critical COVID-19)
Thymosin Alpha 1 Plus Routine Treatment for the Acute Exacerbation of Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta-Analysis
Cao A, Feng F, Zhou X (2024). Journal of the College of Physicians and Surgeons Pakistan. meta-analysis n/a (39 randomised trials, 3,329 patients with acute exacerbation of COPD)