Peptides.media

Comparison

TB-500 vs Thymosin Beta-4

The single most common identity confusion in the recovery-peptide market.

Summary

Thymosin beta-4 is a full-length 43-amino-acid protein with a real research literature; TB-500 is a market name usually attached to fragments of it. Evidence from one does not automatically transfer to the other.

Key answers

Are they the same molecule?

Not exactly. Thymosin beta-4 is the full-length protein. Products sold as TB-500 are usually fragment-based (often centered on the Ac-SDKP region), which share only part of the full protein's biology.

Does the research on thymosin beta-4 apply to TB-500 vials?

Only partially, at best. The full-length protein's actin-sequestering, angiogenic, and anti-fibrotic work involves the whole molecule, and fragment products were not what the studies used. The first question for any TB-500 claim is which exact substance was studied.

What is the regulatory picture for each?

Both are prohibited in sport, with LC-MS detection methods published. TB-500 fragments are also on FDA's 2026 compounding advisory agenda, while full-length thymosin beta-4 has registered trials but no approval.

Comparison matrix

Comparison matrix
DimensionTB-500Thymosin beta-4
Overall evidence gradeED
Evidence labelEvidence unclearLimited human evidence
Regulatory statusInvestigational / not approvedInvestigational / not approved
Editorial confidenceLow confidenceLow confidence
Efficacy0/5 not mapped1/5 limited
Safety1/5 limited1/5 limited
Regulatory risk4/5 high4/5 high
Product quality risk5/5 very high5/5 very high
Primary claim categoriesRecovery claims, Soft-tissue claims, Performance claimsWound-healing research, Ocular surface research, Cardiovascular research, Recovery and soft-tissue claims

Peptide summaries

0/5 efficacy

TB-500

TB-500 is not interchangeable with full-length thymosin beta-4. Current evidence separates Ac-LKKTETQ identity and animal or in-vitro work from adjacent full-length thymosin beta-4 human trial records.

Investigational / not approved
1/5 efficacy

Thymosin beta-4

Thymosin beta-4 has its own evidence. Eye-drop, wound, IV, and registry sources do not prove consumer recovery benefit, and TB-500/Ac-LKKTETQ fragment sources are not interchangeable full-length thymosin beta-4 evidence.

Investigational / not approved

References

  1. 1.

    ClinicalTrials.gov. ClinicalTrials.gov record NCT00382174 2006.

    NCT00382174 Accessed 2026-06-08.

    Full-length thymosin beta-4 trial record; adjacent to TB-500 fragment discussion, not interchangeable evidence.

  2. 2.

    PubMed. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potential 2012.

    PMID:22962027 Accessed 2026-06-08.

    Identity and anti-doping source for TB-500/Ac-LKKTETQ; not human efficacy evidence.

  3. 3.

    FDA. July 23-24, 2026: Meeting of the Pharmacy Compounding Advisory Committee 2026.

    Accessed 2026-07-24.

    FDA meeting page for the July 23-24, 2026 PCAC review of BPC-157, KPV, TB-500, MOTs-C, emideltide/DSIP, Semax, and Epitalon bulk substances, including the uses evaluated for each, briefing documents, and docket FDA-2025-N-6895.