Recovery
TB-500
Thymosin beta-4 fragment
TB-500 is a synthetic peptide based on a short fragment of thymosin beta-4, a protein the body uses in tissue repair. It is discussed for recovery, but the product itself has almost no published human research.
Key facts
- Commonly discussed for: wound healing and soft-tissue recovery.
- Evidence (D): Human trials used full-length thymosin beta-4, not TB-500: for example a 9-patient phase 2 dry-eye trial and a 40-person IV safety study. Anti-doping chemists identified TB-500 as containing a 7-amino-acid fragment, and no controlled human trial of that product has been published.
- FDA status: PCAC recommended. After TB-500 left FDA's Category 2 list in April 2026, the PCAC voted 8-6 (1 abstention) on July 23, 2026 to recommend it for the 503A Bulks List for wound healing; FDA must still publish a proposed rule; none appeared in the Federal Register as of October 1, 2026.
- Legitimate access: No clear legal route yet.
- Last reviewed: October 1, 2026.
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Open my stack →Sources
- Esposito et al. Characterization of the thymosin beta 4 fragment identified in TB-500. Drug Test Anal, 2012
- Sosne et al. Thymosin beta 4 improves signs and symptoms of severe dry eye in a phase 2 randomized trial. Cornea, 2015
- Ruff et al. Randomized, placebo-controlled study of intravenous thymosin beta 4 in healthy volunteers. Ann N Y Acad Sci, 2010
- McDermott Will & Schulte: PCAC backs majority of peptides in two-day public meeting (July 2026)
- Federal Register notice of PCAC meeting and uses under review (April 16, 2026)