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TB-500

Also known as Thymosin beta-4 fragment, LKKTETQ

Sold on research into thymosin beta-4, a different, longer molecule. FDA says it has no human exposure data for the fragment itself.

Information only. Not medical advice. Talk to a doctor before you start, stop or change anything.

What people claim

  • Speeds up injury repair
  • Reduces inflammation and scar tissue
  • Has the same benefits as thymosin beta-4

What the evidence shows

  • FDA says it has no human exposure data and lacks important safety information.[1]
  • Human research is mostly on full-length thymosin beta-4 in eye and wound settings. Those results do not verify the fragment sold as TB-500.[2]
  • In November 2026, TGA testing found some products labelled TB-500 contained none that could be detected.[3]
  • The October 2026 US policy allows compounding in limited cases. It is based on enforcement discretion and does not show that it works.[4][5]

Known risks

  • Human safety is unknown.[1]
  • FDA flags possible immune reactions from aggregation and impurities.[1]
  • Regulator testing shows products may not contain what the label says.[3]
  • Thymosin beta-4 and its derivatives, including TB-500, are banned in sport at all times.[7]

Reported side effects

Moderated user reports are not open yet, so nothing is shown here. They will be labelled as unverified personal accounts.

Legal status

A summary, not legal advice. Rules change, and sport bans are separate.

United States

Unapproved, compounding tolerated

An interim HHS policy from 28 Oct 2026 covers injectable forms from licensed compounding pharmacies, on a patient-specific prescription. It is not FDA approval, and "research use" products are not covered.

United Kingdom

Unlicensed

No licensed medicine contains it.

Australia

Not approved

TGA names it among unapproved peptides and says importing, advertising or supplying them is unlawful.

European Union

Not authorised

No authorised medicine. National rules on possession and import differ.

Sources

  1. 1.Bulk drug substances that may present significant safety risksUS FDA
  2. 2.TB-500: benefits, safety, legal status and researchBSCG
  3. 3.TGA testing finds unapproved peptides do not contain what their labels claimTGA Australia, Nov 2026
  4. 4.HHS interim enforcement discretion policy for six peptides (legal summary)Holland & Knight, Nov 2026
  5. 5.Not approved, not listed: the HHS peptide proposalScience-Based Medicine
  6. 6.Importing, compounding and supplying unapproved peptide productsTGA Australia
  7. 7.Thymosin beta-4 peptide hormone informationSport Integrity Australia

Profile last checked 7 Nov 2026.