TB-500 is a synthetic seven-amino-acid peptide, Ac-LKKTETQ, corresponding to residues 17–23 of thymosin beta-4. It is sold as a research chemical and is not FDA-approved for any indication in the United States.

Is TB-500 the same as thymosin beta-4?

No. Thymosin beta-4 is a 43-amino-acid protein. TB-500 is a short N-acetylated fragment of that sequence. Evidence generated on the full-length protein does not automatically transfer to the fragment.

It is not FDA-approved for human use in the US and is typically sold for research use only. It is prohibited at all times in sport under WADA 2026 section S2.3 as a thymosin-β4 derivative. This is not legal advice.

Does TB-500 heal injuries?

We could not locate a published human randomized controlled trial of the heptapeptide for musculoskeletal or tissue-repair outcomes. Much marketing rests on literature about full-length thymosin beta-4 or on non-human data.

Research peptidestb-500

TB-500: What It Is, and Why It Is Not Thymosin Beta-4

TB-500 is a seven amino acid fragment, not the full protein people cite for it. What that changes about the evidence, plus legal status and the WADA ban.

Written bySebastian Hunter, Founder and Editor

Published July 16, 2026Updated August 22, 2026

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Plain English

TB-500 is usually sold as a short fragment related to thymosin beta-4 rather than the full natural protein, and that distinction changes which research applies to it. Human evidence is limited, and it is not an approved treatment.

Fragment vs full-length thymosin beta-4 is a critical distinction.
Marketing often borrows evidence from the wrong molecule.
Research-chemical legal and purity issues still apply.

If you have searched TB-500, you have almost certainly been shown evidence that belongs to a different molecule.

TB-500 is not thymosin beta-4

TB-500 is Ac-LKKTETQ - a seven-residue, N-acetylated synthetic fragment corresponding to residues 17–23 of thymosin beta-4 (Tβ4). Tβ4 itself is a 43-amino-acid protein.

A 7-mer is not a 43-mer. Laboratory and clinical work on full-length Tβ4 does not automatically describe what TB-500 does in a vial sold online.

That single distinction undoes a large share of social-media citations.

What the fragment is sold for

Vendors market TB-500 for tissue repair and recovery. That is marketing language, not an approved indication.

We could not locate a published human randomized controlled trial of the heptapeptide for a musculoskeletal or tissue-repair endpoint. Treat “it heals tendons” as an unproven claim for this molecule.

Mechanism language - keep it in the lab

In vitro actin-binding work describes the motif binding and sequestering monomeric G-actin, which can influence cytoskeletal dynamics and cell migration in laboratory systems. That is not a human outcome trial.

Evidence strength

Animal / lab only

Studied in cells or animals. No controlled trials in humans. In vitro and animal work for related sequences; no published human RCT of the heptapeptide for tissue-repair indications that we could locate. Full-length Tβ4 literature is frequently mis-cited as TB-500 evidence.

Legal and sport status

US legal status - Research use only · not for human use

Sold for laboratory research use only. Not approved by the FDA for human use, and cannot be lawfully marketed as a supplement or a medicine. Products sold this way are not made to pharmaceutical quality standards, and their contents are not verified by anyone.

AU legal status - Not on the ARTG

Schedule 4 of the Poisons Standard, and Appendix D, clause 5 - prescription only, and possession without authority is illegal. The Poisons Standard lists "TB-500" and "Thymosin beta 4" as separate entries, so the distinction this page exists to draw is one the TGA draws too, and both sides of it are captured. Nothing containing either is on the ARTG.

Regulators reach their own conclusions on their own timelines. Where these two disagree, the difference is the point - not an error.

Not FDA-approved in the US for any indication.
Sold as a research chemical / not for human use - that label is a sales posture, not a purity certificate. See research peptides and the law.
WADA 2026 lists Thymosin-β4 and its derivatives e.g. TB-500 under S2.3, prohibited at all times. The ban groups parent and fragment; that is a regulatory grouping, not proof they are chemically identical.

Practical next reads

BPC-157 - another research compound with thin human data
Ipamorelin
CJC-1295
Are peptides safe?
All compounds

References

Bibliographic detail is fetched from PubMed, not written by us - so a citation here cannot drift from the paper it names. Study design comes from PubMed's own tags rather than our judgement.

1.WADA 2026 Prohibited List, section S2.3 - Growth Factors and Growth Factor Modulators, listing Thymosin-ß4 and its derivatives e.g. TB-500 as prohibited at all times (national anti-doping agency mirror, PDF).- World Anti-Doping Agency (mirrored by the Jamaica Anti-Doping Commission)regulatory
2.Wikipedia - TB-500. Secondary source used only for the Ac-LKKTETQ structure, the fragment-versus-parent distinction, and non-US prescription notes reported there.- Wikipediaother
3.Therapeutic Goods (Poisons Standard - June 2026) Instrument 2026, the current Poisons Standard (SUSMP). "TB-500" and "Thymosin beta 4 (Thymosin B4)" are separate Schedule 4 (prescription only) entries, both also in Appendix D, clause 5 - possession without authority is illegal.- Federal Register of Legislation, Australian Governmentstatute
4.TGA - Unapproved therapeutic goods. Goods not on the ARTG have not been assessed by the TGA for safety, quality or effectiveness, and reach patients only through defined pathways such as the Special Access Scheme.- Therapeutic Goods Administration, Australian Governmentregulatory