TB-500: Benefits, Dosage and What the Evidence Shows
TB-500 is not a natural molecule. It is a synthetic fragment of thymosin beta-4, a protein present in nearly every human cell and in wound fluid, where it plays a role in the repair response. The fragment isolates the part of that protein that binds actin — which is where most of its regenerative activity comes from.
How TB-500 works
Actin is the structural protein cells use to move. Thymosin beta-4 binds actin and regulates its assembly, which controls how cells migrate — and cell migration is the rate-limiting step in tissue repair. When tissue is damaged, healing requires fibroblasts, endothelial cells and keratinocytes to physically travel to the site.
Three documented effects follow from that: increased cell migration into damaged tissue, angiogenesis (formation of new blood vessels, which brings the blood supply repair requires), and downregulation of inflammatory mediators. Thymosin beta-4 also upregulates laminin-5 and appears to influence stem cell differentiation in cardiac repair models.
What the research covers
Wound healing
This is the strongest area. Thymosin beta-4 accelerated dermal wound repair in animal models and progressed into human clinical trials for chronic wounds including venous stasis and diabetic foot ulcers, plus ophthalmic trials for corneal epithelial defects. Those trials studied the full protein, not the TB-500 fragment — a distinction usually lost in product marketing.
Cardiac repair
Two Nature papers underpin this, and they report different things. Bock-Marquette and colleagues (2004) found thymosin beta-4 activated the PINCH/ILK/Akt complex, promoting cardiomyocyte survival and migration after infarction. Smart and colleagues (2007) reported that it mobilized adult epicardial progenitor cells and drove neovascularization. Together they are the most striking regenerative findings in the literature — and both are mouse findings.
Soft tissue and tendon
This is what TB-500 is actually sold for, and it is where the published evidence is thinnest in humans. Animal and veterinary research — particularly equine tendon work — supports improved healing, which is a real body of evidence. Controlled human trials for tendon or muscle injury do not exist.
Dosing references
Protocols in circulation follow a loading-then-maintenance structure, based on the idea that tissue saturation matters early and less thereafter:
| Phase | Common amount | Frequency | Duration |
|---|---|---|---|
| Loading | 2–2.5 mg | 2× weekly | 4–6 weeks |
| Maintenance | 2 mg | Every 1–2 weeks | Ongoing as needed |
TB-500 acts systemically rather than only locally, so protocols generally do not require injection at the injury site — a practical difference from compounds that depend on local concentration.
| Vial | Water | Concentration | 2 mg dose | 2.5 mg dose | Doses per vial (2 mg) |
|---|---|---|---|---|---|
| 5 mg | 2 ml | 2.5 mg/ml | 80 units | 100 units | 2.5 |
| 5 mg | 2.5 ml | 2 mg/ml | 100 units | — | 2.5 |
| 10 mg | 2 ml | 5 mg/ml | 40 units | 50 units | 5 |
Formula: concentration = peptide (mcg) ÷ water (ml). Volume = dose ÷ concentration. One unit on a U-100 insulin syringe = 0.01 ml. Values are for laboratory reference only.
TB-500 and BPC-157 together
The pairing is common enough to have its own name in the community ("Wolverine" stacks). The rationale is complementary mechanisms rather than additive potency: BPC-157 has stronger local and gastrointestinal data and acts partly through the VEGFR2 pathway, while TB-500 works systemically on cell migration. Blend vials typically pair 5 mg of each; remember that a 5/5 mg vial holds 10 mg total and each draw delivers both.
Side effects and status
No controlled human safety data exists. Reports describe injection-site irritation, transient lethargy and occasional head-rush after administration. The structural concern raised in the literature is the same one that applies to any angiogenic compound: stimulating new blood vessel growth is not desirable in the presence of a tumor, since tumors depend on angiogenesis. This is theoretical, unresolved, and worth knowing.
TB-500 is prohibited by WADA at all times — thymosin-β4 and its derivatives are listed specifically under S2.3 (growth factors and growth factor modulators). Anyone in tested sport should treat it as a certain positive.
TB-500 — 5 mg / 10 mg — American Peptides
Available individually and in BPC-157 blends. Batch-tested with HPLC and mass spectrometry. Research use only.
We may earn a commission if you buy through this link (at no extra cost to you). Sold for research purposes only.
Frequently asked questions
What is TB-500?
TB-500 is a synthetic fragment of thymosin beta-4, a naturally occurring protein involved in cell migration and tissue repair. The fragment contains the actin-binding domain responsible for most of the parent protein's regenerative activity.
What is TB-500 used for in research?
Published work centers on wound healing, tissue repair and angiogenesis. Thymosin beta-4 has been studied in corneal and dermal wound healing and in cardiac repair after injury, and TB-500 is used in animal and veterinary research for soft tissue and tendon recovery.
What TB-500 dose is used in protocols?
Research protocols commonly reference a loading phase of about 2–2.5 mg twice weekly for four to six weeks, followed by a maintenance dose around 2 mg every one to two weeks. No human clinical trial has established a dose, so these figures are practice-based.
What is the difference between TB-500 and BPC-157?
They work through different mechanisms and are often studied together. TB-500 acts systemically on actin and cell migration, favouring broad tissue repair and new blood vessel formation. BPC-157 acts more locally with strong gut and tendon data. Neither replaces the other.
Is TB-500 banned in sport?
Yes. TB-500 and thymosin beta-4 are prohibited by the World Anti-Doping Agency under the growth factors and modulators category, in and out of competition. Anyone subject to drug testing should treat it as a positive test risk.
Sources
- Bock-Marquette I et al. Thymosin β4 activates integrin-linked kinase and promotes cardiac cell migration, survival and cardiac repair. Nature, 2004;432(7016):466–72. PubMed
- Smart N et al. Thymosin β4 induces adult epicardial progenitor mobilization and neovascularization. Nature, 2007;445(7124):177–82. PubMed
- Malinda KM et al. Thymosin β4 accelerates wound healing. Journal of Investigative Dermatology, 1999;113(3):364–8. PubMed
- Goldstein AL, Hannappel E, Kleinman HK. Thymosin β4: actin-sequestering protein moonlights to repair injured tissues. Trends in Molecular Medicine, 2005;11(9):421–9. PubMed
- Philp D, Kleinman HK. Animal studies with thymosin β4, a multifunctional tissue repair and regeneration peptide. Annals of the New York Academy of Sciences, 2010;1194:81–6. PubMed
- World Anti-Doping Agency. Prohibited List 2026, section S2.3 — lists “Thymosin-β4 and its derivatives e.g. TB-500”. WADA Prohibited List