TB-500

TB-500 is sold online labeled "not for human consumption," specifically to avoid FDA drug regulation. There is little to no human safety data. This page describes what's known — not dosing or usage guidance, and not a recommendation to use it. Talk to a doctor before considering it.

TB-500 is a synthetic fragment/analog of thymosin beta-4, a protein naturally involved in cell structure and migration. Its proposed mechanism, based entirely on animal and cell-culture research, involves regulating actin (a structural protein) to promote cell movement and tissue repair — the basis for its marketing around injury recovery.

There are no completed human clinical trials of TB-500. What exists is preclinical — animal and cell studies looking at wound healing and tissue repair. There is essentially no human evidence for safety or effectiveness, which is different from "the human evidence is weak" — for TB-500 specifically, it doesn't meaningfully exist yet.

TB-500 has never been FDA-approved for any use. It is sold as a "research chemical," explicitly labeled not for human consumption — language sellers use specifically to operate outside FDA drug regulation. Its compounding-pharmacy status has shifted more than once in 2026: previously restricted from compounding (the FDA's "Category 2" list), that restriction was lifted effective April 22, 2026 when the nomination was withdrawn, and on July 23, 2026 the FDA's Pharmacy Compounding Advisory Committee voted 8-6 (with one abstention) to recommend adding it to the compounding-permitted list. That's a recommendation, not a rule change — compounding pharmacies cannot legally use TB-500 under Section 503A until the FDA completes formal rulemaking, which typically takes 8–24 months. None of this amounts to drug approval; it only affects whether a compounding pharmacy may eventually be allowed to prepare it. See our Peptides hub page for the fuller regulatory picture across this group of compounds. It's also prohibited at all times in competitive sport under the World Anti-Doping Agency's Prohibited List.

FDA — Bulk Drug Substances Used in Compounding →

With no completed human trials, real risks in people — immune reactions, impurity from unregulated manufacturing, long-term effects — are unstudied rather than ruled out. Products sold as "TB-500" also carry the additional, practical risk of unverified purity and dosing consistency, since they aren't manufactured under pharmaceutical quality standards.

FDA — Bulk Drug Substances Used in Compounding Under Section 503A