What is TB-500?

By The Docket DeskResearched & sourcedUpdated 18 Jun 2026

TB-500 is a synthetic fragment related to thymosin beta-4, a naturally occurring protein involved in cell migration and repair. It is marketed for wound healing and recovery. It is not approved as a medicine in the US.

What the evidence shows

EVIDENCE GRADE · PRECLINICAL · LIMITED HUMAN DATA

Evidence for TB-500 is largely from animal and laboratory studies; controlled human trials for the marketed uses are lacking. The FDA placed it in Category 2 in 2023 over concerns including impurities and insufficient human safety data, so efficacy in people is unproven and its long-term safety is not established.

Is it legal?

TB-500 is not FDA-approved. In April 2026 it was removed from FDA Category 2 but not moved to the approved Category 1 list, so legal compounding is not authorized; the PCAC reviews it on July 23, 2026.

FDA approvalNot approved

Compounding statusRemoved from Category 2 (Apr 2026, nominations withdrawn) · not on Category 1 — compounding not authorized

Under FDA reviewPCAC · July 23, 2026

Use under reviewWound healing

Earliest pharmacy accessLate 2026–Q1 2027 (if cleared)

Will TB-500 become legal in 2026?+

Not automatically. The committee meets July 23, 2026; a favorable vote is a recommendation only — the FDA must then issue a final rule, which typically takes months. Realistic legal compounded access is late 2026 to Q1 2027, and only if both steps go through.

Is “research-grade” TB-500 the same as a medicine?+

No. Material sold “for research use only” is not made or tested to pharmaceutical standards, is not authorized for human use, and carries no guarantee of identity, purity or sterility. This site does not link to or evaluate these sellers.

Primary sources: FDA 503A interim list (Category 2, 2023) · FDA Advisory Committee Calendar; Federal Register docket FDA-2025-N-6895.

Medical & editorial disclaimer. This article is independent reference information, not medical advice and not a recommendation to use any substance. TB-500 is not FDA-approved. Nothing here should be used to obtain, prepare, or self-administer any drug. Talk to a licensed clinician about your health. Peptide Docket is not affiliated with the FDA and does not sell peptides.