TB-500

No human trials of TB-500 exist. This is the single most important fact on this page. TB-500 is not thymosin beta-4. Analytical characterization of commercial TB-500 identified its active ingredient as Ac-LKKTETQ, the N-terminal acetylated 17-23 fragment of the 43-amino-acid human peptide thymosin beta-4 (Esposito 2012, PMID: 22962027). TB-500 is described as a veterinary preparation, and it has been detected in equine urine and plasma after administration to horses (Ho 2012, PMID: 23084823). Every human study in the published literature used full-length synthetic thymosin beta-4, not the TB-500 fragment. Those include an intravenous Phase 1 safety study in 40 healthy volunteers (Ruff 2010, PMID: 20536472), small Phase 2 eye-drop trials in dry eye (UNCITED: the cited PMID did not support this claim and was removed; this statement is not currently sourced), and Phase 2 topical dermal wound trials in pressure ulcers, stasis ulcers, and epidermolysis bullosa reported in review (Kleinman 2016, PMID: 27450738). None of them tested tendon, muscle, joint, or general recovery outcomes, and none of them used an oral or subcutaneous consumer product. A 2026 PRISMA scoping review of TB-500 and five other marketed peptides found 67 percent of identified publications used preclinical animal models, with human studies limited to a handful of investigations mostly lacking robust controls (Tewari 2026, PMID: 42578445). Regulatory status is unfavorable: peer-reviewed reviews describe TB-500 as an unapproved compound sold on a gray market operating largely outside of regulatory oversight (Mendias 2026, PMID: 41966639) and confirm that both thymosin beta-4 and TB-500 remain banned substances in sport (Mayfield 2026, PMID: 41476424). Avelor grades this INSUFFICIENT and does not consider it a supportable ingredient in a consumer supplement.