TB-500

TB-500 is a synthetic peptide best known for research into tissue healing and recovery — tendon, ligament, wound, and cardiac repair. It's based on a fragment of thymosin beta-4 (Tβ4), a protein naturally involved in tissue repair. It is not FDA-approved for any use, and most of the published research is on the full thymosin beta-4 molecule rather than the TB-500 fragment that's actually sold, so human evidence specific to TB-500 is limited. It's also banned by the World Anti-Doping Agency in competitive sport.

TB-500 has been studied for tissue healing and recovery. Most research is in animals and on full thymosin beta-4 (its parent molecule) — those studies reported faster healing in wound and cardiac repair models. Human evidence specific to the TB-500 fragment is very limited, so the tendon, ligament, and recovery uses people pursue have not been confirmed in people and rely on extrapolation from the parent molecule plus user reports.

Not FDA approved for any indication. Banned by the World Anti-Doping Agency (WADA) in human sport and by major equine racing authorities. TB-500 was a named subject of FDA's 503A Bulks List review and was voted on at the Pharmacy Compounding Advisory Committee meeting held July 23, 2026 (separate votes on the free base and the acetate); FDA's own briefing document proposed that neither form be added. FDA has published no summary minutes, vote results, or determination from that meeting as of 2026-09-03, and a PCAC recommendation is advisory and non-binding, so TB-500 is not on the 503A Bulks List and is not compoundable under 503A on that basis (as of 2026-09-03). Not permitted for 503A compounding under current policy; not FDA-approved; not DEA-scheduled.

TB-500 is not FDA-approved, and its safety in humans has not been established in clinical trials. It is also banned in regulated sport (WADA). VialWise is a research and educational reference, not medical advice — consult a licensed professional.

⚠️ For research and educational purposes only. TB-500 is not approved by the FDA for any indication and is banned in regulated human and equine sport. Information in this entry is informational, not medical advice. Always confirm dose calculations with the in-app calculator and consult appropriate professional guidance before any protocol decisions.

⚠️ Precision matters at low doses. Small dosing errors that look trivial in absolute terms can be significant in percentage terms when starting doses are small. A one-unit mis-draw at a 5-unit dose is a 20% error; the same one-unit error at a 50-unit dose is only 2%. TB-500 is dosed in milligrams (typically) and produces draws in the range at common reconstitutions, where precision is less acute than for microgram-dosed peptides — but the inverse problem (draw exceeding U-100 syringe capacity at low-concentration reconstitutions) is more common. Always verify draws against the in-app calculator.

⚠️ TB-500 is not the same molecule as full thymosin beta-4. Most of the published clinical and preclinical literature is on full thymosin beta-4 (Tβ4) — a 43-amino-acid endogenous peptide. TB-500 as commonly sold and used in the research community is a synthetic fragment of Tβ4 — specifically, the N-terminal acetylated 17-23 amino acid sequence, as identified and characterized in published doping-control literature.[⁶] The research community frequently treats TB-500 and full Tβ4 as equivalent; the published literature does not. Claims about TB-500 efficacy that extrapolate from full-Tβ4 trials are making an assumption that should be explicit. This entry treats them as related but distinct compounds and flags inline where a citation refers to full Tβ4 vs TB-500 fragment specifically.

TB-500 is a synthetic peptide commonly described as a "fragment of thymosin beta-4 (Tβ4)." Tβ4 itself is a 43-amino-acid actin-sequestering protein that occurs naturally in human cells (especially platelets and tissue) and has been studied for over two decades for its role in tissue repair, cell migration, anti-inflammatory effects, and angiogenesis.[¹] TB-500 as commonly sold in the research-peptide community is a synthetic short fragment derived from Tβ4's actin-binding region; the exact sequence varies by source, with the 7-amino-acid Ac-SDKP fragment being one common form.

Regulatory status. TB-500 has never received FDA approval for any indication. The full Tβ4 molecule (under the development name TB4-001 and others) has progressed through several clinical trials in regenerative medicine — particularly for corneal wound healing and dry eye — but has not received FDA approval for any major indication. TB-500 specifically is banned by the World Anti-Doping Agency (WADA) in human sport under section S2.3 (Growth Factors and Growth Factor Modulators) — named verbatim as *"Thymosin-ß4 and its derivatives e.g. TB-500"*, prohibited at all times[⁵] — and is similarly banned by major horse racing authorities. On US compounding: TB-500 (both free base and acetate) is one of several peptides FDA is reviewing for the 503A Bulks List at a Pharmacy Compounding Advisory Committee (PCAC) meeting on July 23–24, 2026 — the same docket that includes BPC-157, KPV, and MOTS-c. FDA's published briefing materials propose that TB-500 not be added, citing that it is not physically or chemically well characterized (inconsistent INN/USAN/IUPAC naming), that there is no human effectiveness data (including an in-vitro study in which TB-500 did not induce fibroblast wound healing), and that human safety data is insufficient, with injection-site immunogenicity risk unassessed. A PCAC recommendation is advisory and FDA is not bound by it, so the accurate current framing is "FDA proposing against inclusion, determination pending" — not a decided outcome. TB-500 is not FDA-approved for any indication and is not a DEA-controlled substance (not scheduled under the Controlled Substances Act). `[confirm the final PCAC outcome — FDA had published no minutes, vote results, or determination as of 2026-09-03; re-check before App Store submission; lock the interim 503A Category-2 listing/removal dates against fda.gov/media/94155 before shipping any interim-status wording]`

Mechanism. Mechanism claims for TB-500 are extrapolated from the full Tβ4 mechanism literature. Tβ4 functions as an actin-sequestering protein that regulates cell migration, particularly of endothelial cells, keratinocytes, and stem/progenitor cells. The proposed downstream effects include: angiogenesis through VEGF pathway upregulation, anti-inflammatory effects through suppression of NF-κB activation, promotion of collagen deposition, and acceleration of wound healing.[¹][²] Whether the synthetic short fragment marketed as TB-500 reproduces all of these effects, or only a subset, is not well established in the published literature.

Evidence quality. As with BPC-157, the published evidence base for TB-500 specifically is limited. Most rigorous published studies are on the full Tβ4 molecule (Goldstein lab, RegeneRx development program for corneal and dry eye indications, cardiac-repair preclinical work).[¹][³] Research-community use of the TB-500 fragment is based on a combination of (a) extrapolation from full-Tβ4 mechanism work, (b) accumulated researcher experience for tendon/ligament recovery, and (c) the parallel literature on BPC-157, with which TB-500 is commonly stacked. The veterinary literature (especially equine) provides additional but non-rigorous data on TB-500 fragment use.

Common research interests. Despite the limited specific clinical evidence base, TB-500 is one of the most commonly used regenerative peptides in the research community, primarily for: - Tendon and ligament injury recovery (most common, often stacked with BPC-157) - Soft tissue injury and post-surgical recovery - Wound healing - Adjunct to athletic recovery protocols (note: prohibited by WADA in regulated sport)

These uses are based on extrapolation from preclinical Tβ4 data plus accumulated researcher experience. They are not FDA-approved indications, and the evidence specific to the TB-500 fragment (vs full Tβ4) is thinner still.

Commonly reported

• Injection site reactions (local redness, soreness)
• Mild lethargy or fatigue, especially during the loading phase
• Transient flu-like symptoms during the first 1–2 weeks (uncommon)
• No consistent pattern of serious adverse events in the published preclinical or case-report literature
• Angiogenic activity in the context of malignancy — same theoretical concern as BPC-157 and full Tβ4. The VEGF-promoting and angiogenesis-promoting effects raise a theoretical concern about supporting tumor vasculature in researchers with active or undiagnosed malignancy. Not validated in clinical data but is the most commonly cited theoretical safety issue.
• Long-term safety in humans is essentially unknown for the TB-500 fragment. No multi-year human safety dataset exists.

Active malignancy or undiagnosed cancer concern — theoretical contraindication based on angiogenic mechanism shared with full Tβ4 (see Side Effects section)

Pregnancy and lactation: no data; default to contraindicated — no published reproductive toxicology in humans

Pediatric use: no data — should not be used in researchers under 18

Active anti-coagulation regimens — no published interaction data; theoretical concern given vascular effects

Concurrent immunosuppressive or chemotherapeutic regimens — no published interaction data

WADA-banned in regulated sport. Researchers competing in any WADA-tested sport, or any regulated equine racing context, will test positive. This is a regulatory compliance issue, not a safety issue, but is the most common reason a researcher would need to disclose use.

Regulatory note (US): TB-500 (free base and acetate) is under FDA review for the 503A Bulks List at the Pharmacy Compounding Advisory Committee meeting of July 23–24, 2026 — the same batch as BPC-157, KPV, and MOTS-c. FDA's briefing materials propose it not be added, citing insufficient characterization, no human effectiveness data, and insufficient human safety data. The committee met and voted on July 23, 2026, but FDA has published no minutes, vote results, or determination as of 2026-09-03, so treat the status as *FDA proposed against inclusion; committee recommendation unpublished and advisory in any case; no FDA determination* rather than decided. TB-500 is not FDA-approved and is not DEA-scheduled. `[confirm the final PCAC outcome — FDA had published no minutes, vote results, or determination as of 2026-09-03; re-check before App Store submission]`

Peptide

A short chain of amino acids, the building blocks of proteins. Many compounds in this library are peptides.

Preclinical

Research done in cells or animals, before human clinical trials. Promising preclinical results don't always hold up in people.

Subcutaneous

An injection into the fatty layer just under the skin, rather than into a muscle or vein.

WADA Prohibited List

The list of substances banned in regulated sport by the World Anti-Doping Agency.

1. Goldstein AL, Hannappel E, Sosne G, Kleinman HK. (2012). Thymosin β4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opinion on Biological Therapy, 12(1):37–51.(PMID 22074294)
2. Crockford D, Turjman N, Allan C, Angel J. (2010). Thymosin beta4: structure, function, and biological properties supporting current and future clinical applications. Annals of the New York Academy of Sciences, 1194:179–189.(PMID 20536467)
3. Bock-Marquette I, Saxena A, White MD, Dimaio JM, Srivastava D. (2004). Thymosin beta4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature, 432(7016):466–472.(PMID 15565145)
4. Sosne G, Qiu P, Goldstein AL, Wheater M. (2010). Biological activities of thymosin beta4 defined by active sites in short peptide sequences. FASEB Journal, 24(7):2144–2151.(PMID 20179146)
5. World Anti-Doping Agency. The 2026 Prohibited List, International Standard (effective 1 January 2026). Canonical PDF: wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf (linked from the WADA landing page at wada-ama.org/en/prohibited-list; local archival copy in `docs/legal/wada-2026-prohibited-list.pdf`). TB-500 is named explicitly under Section S2.3 (Growth Factors and Growth Factor Modulators) — not under S2.2. Verbatim wording from the canonical PDF, page 8: "Thymosin-ß4 and its derivatives e.g. TB-500" — listed alongside Fibroblast growth factors (FGFs), Hepatocyte growth factor (HGF), Insulin-like growth factor 1 (IGF-1, mecasermin) and its analogues, Mechano growth factors (MGFs), Platelet-derived growth factor (PDGF), and Vascular endothelial growth factor (VEGF). The S2.3 catch-all clause reads verbatim: "and other growth factors or growth factor modulators affecting muscle, tendon or ligament protein synthesis/degradation, vascularisation, energy utilization, regenerative capacity or fibre type switching." Prohibited at all times.
6. Esposito S, Deventer K, Goeman J, Van der Eycken J, Van Eenoo P. (2012). 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. Drug Testing and Analysis, 4(9):733–738.(PMID 22962027)
7. Mendias CL, Awan TM. (2026). Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance. Sports Medicine (Auckland).(PMID 41966639)
8. Nguyen C, Allen MR, Hornburg K, Fredericson M. (2026). Effects of Supplementation in Masters Athletes and Older Adults: A Narrative Review. Current Sports Medicine Reports, 25(7):216–223.(PMID 42385164)

• BPC-157 — discussed together in this entry's stacks section
• ARA-290 — same mechanism class
• BPC-157 / TB-500 Blend — same mechanism class
• GHK-Cu — same mechanism class
• GLOW — same mechanism class
• KLOW — same mechanism class