Synthetic thymosin beta-4 fragment
TB-500
A seven-amino-acid thymosin fragment promoted for repair despite an unresolved human-outcome gap, significant product questions, and anti-doping prohibition.
Also known as TB500 · Ac-LKKTETQ · thymosin beta-4 fragment 17-23
01 · Evidence profile
One molecule, four evidence questions
FDA found no adequate human clinical outcome evidence for compounded TB-500 wound-healing use.
Fragment identity and laboratory findings do not establish a clinical benefit in people.
Human exposure and product-specific safety information are inadequate.
Nomenclature, salt form, purity, sterility, and fragment-versus-protein distinctions create major uncertainty.
02 · Identity
What it is
TB-500 is reported as the N-terminal acetylated 17-23 fragment of thymosin beta-4. It is not full-length thymosin beta-4, and evidence about the full protein cannot automatically be transferred to the fragment.
03 · Product identity
The molecule is not the finished product.
FDA identifies TB-500 as a seven-amino-acid fragment, not as interchangeable with full-length thymosin beta-4. Internet naming and certificates do not establish product identity or clinical equivalence.
None identified in the United States.
- No FDA-approved indication
04 · Evidence snapshot
What the evidence can and cannot say
FDA has published a detailed 2026 briefing on identity, characterization, proposed wound-healing use, and evidence gaps. WADA explicitly names TB-500 on the 2026 Prohibited List.
Reliable controlled human trials do not establish faster tendon, muscle, or wound healing from TB-500. Safety, purity, sterility, long-term effects, and equivalence of marketed material remain uncertain.
05 · Claim check
Three claims under the lens
“TB-500 is the same thing as thymosin beta-4.”
FDA describes TB-500 as a seven-amino-acid fragment of the much larger thymosin beta-4 molecule.
- Evidence basis
- Regulatory or product record
- Scope
- Chemical identity, not a claim about all possible biological activity.
“TB-500 accelerates tendon and muscle healing in people.”
The FDA evidence review did not identify adequate human outcome evidence for wound-healing use.
- Evidence basis
- No reliable human outcome evidence
- Scope
- Clinical tendon, muscle, and wound-healing outcomes in people.
“TB-500 is allowed in tested sport.”
TB-500 is named on the current WADA Prohibited List.
- Evidence basis
- Regulatory or product record
- Scope
- Sport governed by the World Anti-Doping Code.
06 · Safety boundary
Before this becomes personal
This is not an invitation to experiment. The guide provides no sourcing, reconstitution, injection, cycle, stack, or injury-treatment instructions.
TB-500 is named as a prohibited thymosin-beta-4 derivative on the 2026 WADA Prohibited List.
Reviewed 2026-07-23. This status is not personal clearance to compete.Check the governing record ↗07 · Sources
Check the primary record
08 · Provenance
Review history
Initial brief uses FDA's July 2026 identity and evidence review before final agency action.
Responsible editor: Anthony Treviso. Editorial source review completed. This page has not been independently medically reviewed by a physician or pharmacist.