TB-500
Also called: thymosin beta-4, peptide tb 500, tb500
Clinical reviewer: Jacob Moore, MD · Last checked September 16, 2026
What is TB-500?
TB-500 is a synthetic seven-amino-acid fragment of the natural protein thymosin beta-4, covering amino acids 17 to 23 with an acetyl group at one end. It is sold for wound healing and recovery, is not FDA-approved, has no human clinical studies FDA could identify, and its 503A nomination was withdrawn, leaving FDA to evaluate it on its own initiative.
What does research show about TB-500?
Very little in people. FDA evaluated TB-500 for wound healing and reported that its search did not identify clinical studies of TB-500 in humans, nor case reports in the published literature [1]. It concluded that evidence is lacking to support wound-healing effects, and that nonclinical toxicology studies are not available either [1]. A 2026 review lists TB-500 among unapproved peptides with animal-model signals but scarce human safety data [4].
Is TB-500 legal or FDA-approved?
Neither. FDA's safety-risk list records its nomination as withdrawn and notes possible immunogenicity from aggregation and peptide impurities, with no human exposure data [2]. In its July 2026 briefing, FDA staff said the criteria weigh against adding it to the 503A bulks list [1]. The advisory committee nonetheless voted 8 to 6, with one abstention, to recommend it on July 23, 2026; the vote is not binding and any change requires formal rulemaking [3]. Its legal position is the same as BPC-157.
Is TB-500 safe?
Unknown. FDA wrote that potential safety risks in humans are unknown and that it is particularly concerned about the absence of human data for any route [1]. It also flagged that "TB-500" is a common name under which different salts and derivatives are sold, so buyers cannot be sure what they receive [1]. No validated human dose exists, so this page gives none.
Related terms
Sources
- FDA Briefing Document — Pharmacy Compounding Advisory Committee Meeting, July 23–24, 2026 (TB-500-related bulk drug substances)
- FDA — Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (Category 2), current as of April 22, 2026
- Pharmaceutical Executive — FDA Panel Votes to Loosen Restrictions for Four Peptides (July 24, 2026)
- Mendias CL, Awan TM. Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance. Sports Medicine, 2026.
This entry is for education and is not medical advice. Talk with a licensed clinician about your own situation before starting, stopping, or changing any treatment.
