What Is TB-500? Thymosin Beta-4 and Healing Explained

Research on thymosin beta-4 points to several effects relevant to repair:

• Cell migration: by regulating actin, it helps skin cells, blood vessel cells and stem cells move into damaged areas.
• New blood vessels: it promotes angiogenesis, bringing more blood flow to healing tissue.
• Lower inflammation: it reduces inflammatory signaling in injured tissue.
• Less scarring: animal studies report reduced scar formation in skin and heart tissue.

Wound healing. In rodent studies, applying or injecting Tβ4 sped up skin wound closure and increased collagen deposition and blood vessel growth.

Heart repair. A widely cited 2004 Nature paper (Bock-Marquette et al.) found that Tβ4 improved heart cell survival and heart function in mice after a heart attack.

Eye. The company RegeneRx developed a Tβ4 eye drop (RGN-259) and tested it in human trials for dry eye and neurotrophic keratitis, with mixed results on primary endpoints.

TB-500 specifically. When the FDA reviewed TB-500 in 2026 for wound healing, it reported no direct human administration studies of TB-500 itself.

Both are studied for tissue repair and are often combined (sold as the “Wolverine” blend). They work differently: TB-500 is linked to actin and cell migration, while BPC-157 is linked to growth-factor signaling and blood vessel formation. Neither has strong human trial evidence, and there are no controlled studies of the combination. See our BPC-157 guide for more.

Without human studies, the side effect profile of TB-500 is unknown. A theoretical concern raised by researchers is that compounds promoting cell migration and new blood vessels could, in principle, support tumor growth. This has not been shown, but it has not been ruled out either.

On July 23, 2026, the FDA’s Pharmacy Compounding Advisory Committee voted 8–6, with one abstention, to recommend adding TB-500 to the 503A Bulks List for wound healing. The recommendation is non-binding, TB-500 is not FDA-approved, and pharmacies cannot compound it until the FDA completes rulemaking.

TB-500 is prohibited by WADA and has caused positive tests in horse racing and human sport.

TB-500 is rarely sold on its own anymore. Research suppliers commonly combine it with other repair-focused peptides:

What the research says about blends. None of these combinations has been tested as a combination in controlled studies. The rationale comes from each ingredient’s separate animal research. Blends also make quality control harder: a certificate of analysis needs to confirm the amount of each peptide, not just total purity.

Thymosin beta-4 in horses. TB-500 first became widely known in horse racing, where it was used to support recovery. Racing authorities now test for it, and several trainers have been sanctioned after positive tests.

Products sold as TB-500 by research suppliers are laboratory chemicals, not medicines. They are not made under drug manufacturing rules, so quality varies a lot between vendors. If you are evaluating a TB-500 supplier for lab research, these are the checks that matter:

• Batch-specific COA: the certificate should match the lot number on your vial, not a generic sample.
• Independent lab: testing should come from a named third-party lab, ideally with a way to verify the report online.
• Identity, not just purity: HPLC purity alone does not confirm the right molecule; look for mass spectrometry (MS) identity confirmation.
• Endotoxin and sterility results: these matter for any injectable research material.
• Correct fill amount: the measured content should be close to the labeled milligrams.

Our Trusted Sources page lists vendors we track, with current community codes. Our guide to reading a certificate of analysis explains each line of a COA.

• TB-500 is a synthetic peptide based on thymosin beta-4, a natural actin-binding protein.
• Tβ4 promotes cell migration, blood vessel growth and wound repair in animals.
• The FDA found no direct human studies of TB-500 itself.
• An FDA panel recommended it for compounding 8–6 in July 2026; it is not approved.
• It is banned in sport.

What is TB-500?

TB-500 is a synthetic peptide based on thymosin beta-4, a natural protein that helps cells move and supports wound repair.

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

Not exactly. TB-500 is based on the active region of thymosin beta-4, and products vary. Research on full thymosin beta-4 does not automatically apply to TB-500.

Does TB-500 work in humans?

There are no direct human studies of TB-500. The FDA noted this in its 2026 review. Evidence comes from animal studies of thymosin beta-4.

Is TB-500 FDA-approved?

No. An FDA advisory committee voted 8–6 in July 2026 to recommend it for compounding, but the FDA has not finalized that and it is not an approved drug.

Is TB-500 banned in sports?

Yes. TB-500 is prohibited by the World Anti-Doping Agency.

• Nature – Bock-Marquette et al. (2004), Thymosin β4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair
• Malinda et al. (1999) – Thymosin β4 accelerates wound healing
• Bass, Berry & Sims – FDA advisory committee recommends six peptides for compounding (2026)
• Rite Aid News – July 2026 FDA peptide panel vote: what changed
• World Anti-Doping Agency – Prohibited List