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TB-500 is a synthetic peptide derived from a short active region of thymosin beta-4, a protein found throughout the body that plays a central role in how cells move, repair tissue, and regulate the cytoskeleton. It has attracted interest in research and athletic contexts as a potential recovery and healing compound, though it has no approved medical use in humans and remains strictly a research chemical.
What is TB-500
TB-500 corresponds to amino acids 17-23 of thymosin beta-4 (sequence: Ac-LKKTETQ). It has a molecular weight of approximately 878 Da and is distinct from the full 43-amino acid thymosin beta-4 protein, though the two are often discussed together in research literature. TB-500 is not FDA-approved for any indication, is not a lawful dietary supplement ingredient, and is listed as a prohibited substance by the World Anti-Doping Agency (WADA). It circulates primarily as a research chemical, often sold through online retailers and compounding pharmacies without standardized quality controls.
How it works
The main mechanism behind thymosin beta-4 and its fragments is G-actin sequestration. G-actin is the monomeric form of the structural protein actin; by binding to it, TB-500 prevents it from polymerizing into filamentous F-actin, which helps maintain a flexible pool of actin available for rapid cytoskeletal changes. This process supports several downstream biological functions:
- Cell migration: Cells need to remodel their internal scaffolding to move toward injury sites. TB-500 facilitates this movement by keeping actin in a more responsive, unpolymerized state.
- Angiogenesis: The LKKTETQ sequence appears to promote endothelial cell migration and the formation of new blood vessels, with preclinical data showing upregulation of VEGF and activation of nitric oxide synthase pathways.
- Anti-inflammatory signaling: Animal studies suggest Thymosin Beta-4 downregulates pro-inflammatory mediators including TNF-alpha, IL-1beta, and IL-6, partly through inhibition of the NF-kB pathway.
- Extracellular matrix remodeling: The peptide has been associated with increased collagen deposition and activation of matrix metalloproteinases, both important steps in wound closure and tissue remodeling.
It is worth noting that a 2024 study raised questions about whether TB-500 itself drives wound-healing activity, or whether its active metabolite (Ac-LKKTE) is primarily responsible. This distinction matters when interpreting older preclinical literature.
What the research says
The evidence base for TB-500 is almost entirely preclinical. Animal studies, primarily rodent and equine models, have shown accelerated wound closure, improved muscle and tendon repair, and enhanced cardiac recovery following ischemic injury using thymosin beta-4 or related fragments. These findings have informed significant interest in the compound, but animal data does not directly translate to human outcomes.
In humans, two small Phase 2 trials tested topical thymosin beta-4 in chronic wound settings. One double-blind, placebo-controlled study (n=73) found that 0.03% topical application achieved complete healing in roughly 25% of patients with venous stasis ulcers over three months, with some acceleration of healing time. However, both trials had small sample sizes, methodological limitations, and did not involve systemic injectable TB-500. No Phase 3 trials have been completed for any form of the compound.
The current evidence does not establish clinical efficacy for the injectable, systemic use patterns common in athletic or performance contexts. Most claims about TB-500 for muscle injury, joint repair, or recovery speed in humans are extrapolated from animal data or anecdotal community reports.
Typical dosing
The following dosing ranges are drawn from reported community protocols and limited clinical research. They are not prescriptive recommendations. TB-500 is not approved for medical use, and anyone considering it should consult a qualified healthcare provider.
| Phase | Reported Range | Frequency |
|---|---|---|
| Loading | 2-5 mg/week | 1-2 injections per week |
| Maintenance | 2-2.5 mg/week | 1 injection per week |
| Cycle length | 4-8 weeks (varies) | Followed by a rest period |
Reported injection volumes are typically 50-200 microliters. Subcutaneous delivery is the most commonly reported route. Some protocols describe combining TB-500 with BPC-157 during the same cycle; see our guide on how to reconstitute peptides for preparation basics and injection site rotation for safe administration practices.
All dosing information should be treated with caution. Protocol ranges in the community vary considerably, and there is no established human dose with a proven safety and efficacy profile.
Side effects and safety
TB-500 does not have a formal human safety profile established through clinical trials. Based on reports from clinical use and community self-reporting, the commonly noted adverse effects include:
- Injection site reactions (redness, mild swelling, local discomfort)
- Headache or dizziness
- Mild nausea or gastrointestinal upset
- Fatigue, particularly early in a protocol
Less frequently reported effects include fever, skin rash, muscle aches, blistering at injection sites, and more severe hypersensitivity reactions. The absence of controlled long-term human safety data means the full risk profile, including effects on tumor growth, cardiovascular function, or endocrine signaling with sustained use, is not well characterized.
Because TB-500 is typically sourced as a research chemical without standardized manufacturing oversight, contamination and inaccurate labeling are additional practical concerns. WADA lists the compound as prohibited at all times, placing any competitive athlete who uses it at risk of a multi-year ban.
Tracking TB-500 with Redose
If you are using TB-500 under clinical supervision as part of a structured research protocol, Redose makes it straightforward to log each dose, track injection site rotation, and monitor your schedule from your phone. The free reconstitution calculator handles BAC water ratios and per-dose volumes instantly, so there is no manual math. Download the app at /#download to set up your protocol in under a minute.
This profile is educational information, not medical advice. Talk to a qualified healthcare provider before starting any protocol.