Regulatory status & anti-doping
TB-500’s legal picture is easy to misread. It is sold as a "research chemical", it is not FDA-approved for any use, it…
Legal to buy, not approved, and banned in sport
TB-500’s legal picture is easy to misread. It is sold as a "research chemical", it is not FDA-approved for any use, it was placed on the FDA’s 503A category 2 compounding-restriction list on September 29, 2023 (listed as "Thymosin beta-4, fragment (LKKTETQ)") and then removed from that list, with 11 other peptides, in April 2026 (removal is not approval, and it is still not on the authorized 503A bulks list; on July 23, 2026 the Pharmacy Compounding Advisory Committee voted, by a narrow margin and against the FDA review team’s own written recommendation, to recommend adding TB-500 to that list, but a committee vote is advice, not a decision, and the agency has not acted on it), and it has been banned in sport by WADA since 2018. Its first detection method came out of a human anti-doping laboratory, with racing laboratories following.
This unit maps the jurisdictions, the regulatory timeline, the anti-doping reality, and the gap between "legal to purchase" and "safe or approved".