TB-500
Repair and Recovery
In short
- A synthetic version of the actin-binding region of thymosin beta-4, not the full protein.
- Preclinical work covers wound healing, cardiac repair, and corneal injury; human trials of full-length thymosin beta-4 exist but are limited and did not establish efficacy.
- No published human pharmacokinetics for the TB-500 fragment specifically.
- Explicitly prohibited by WADA at all times, unlike BPC-157 — this matters for any tested athlete.
- Not approved by any regulator. Sold for research use only.
Structure
How it works
Thymosin beta-4 is a 43-amino-acid protein whose main known function is sequestering G-actin, regulating the actin cytoskeleton that drives cell migration. TB-500 corresponds to the short actin-binding sequence within it.
In preclinical models the downstream effects attributed to this are increased cell migration into injured tissue, promotion of angiogenesis, reduced inflammatory signalling, and reduced fibrosis. Whether the isolated fragment reproduces full-length thymosin beta-4 activity in humans has not been established.
What the research shows
Rodent and rabbit models report accelerated dermal wound closure, improved cardiac function after induced infarction, and corneal healing.
Human evidence relates to full-length thymosin beta-4, not TB-500: phase 2 trials in pressure ulcers, venous stasis ulcers, and epidermolysis bullosa were conducted, and did not produce approval.
Use in performance and recovery contexts is anecdotal, uncontrolled, and frequently confounded by concurrent BPC-157 use.
Dosing in the literature
Figures below are quoted from published studies, with the species or population they were measured in. They are records of what was studied, not recommendations.
| Studied in | Amount | Route | Source |
|---|---|---|---|
| Rodent — cardiac and dermal repair models | Commonly in the range of milligrams per kilogram, varying widely by model | intraperitoneal or intravenous | PubMed |
| Human — full-length thymosin beta-4, phase 2 wound trials | Topical and intravenous protocols; see source for schedules | — | PubMed |
Commonly reported ranges
These are amounts people report using. They are not from any study, have not been evaluated for safety, and are reproduced here only because they circulate widely and are better seen alongside the evidence than instead of it.
| Reported by | Amount | Route |
|---|---|---|
| Commonly reported loading phase | 2–5 mg twice weekly | subcutaneous |
| Commonly reported maintenance | 2–5 mg every 1–2 weeks | subcutaneous |
No human pharmacokinetic study of TB-500 has been published, so there is no established dose, interval, or duration. Rodent figures are per kilogram of rodent and do not translate by simple scaling.
Handling and storage
Supplied lyophilised, reconstituted with bacteriostatic water, refrigerated after mixing. Subcutaneous injection is the usual reported route.
Unlike BPC-157, site-local injection has little mechanistic rationale here — the described mechanism is systemic cell migration rather than local action.
Side effects
No systematic safety data exists for TB-500 in humans. Reported issues are mostly local injection-site reactions and transient fatigue or head-rush after dosing.
The mechanistic concern worth understanding is the same as BPC-157 but stronger: a compound promoting angiogenesis and cell migration is promoting two processes central to tumour growth and metastasis. This is theoretical, has not been demonstrated in humans, and has also not been excluded.
Combinations
Most frequently paired with BPC-157 (the Wolverine blend), on the rationale of complementary repair pathways. No controlled human study has tested the combination.
Running both simultaneously makes attribution impossible in either direction.
Research status
The thymosin beta-4 literature is respectable in preclinical volume, concentrated in wound healing and cardiac repair. The TB-500 fragment specifically has far less direct study, and much of what circulates about it is inferred from the parent protein.
No registered clinical trial of TB-500 as sold in the research-chemical market has been completed.
Legal status
Not approved by the FDA or any comparable regulator for any indication. Sold labelled for research use only. In 2023 the FDA included thymosin beta-4 in the category of substances presenting significant safety risks for compounding.
WADA status
PROHIBITED AT ALL TIMES under WADA class S2 (peptide hormones, growth factors, related substances and mimetics). This is a meaningful difference from BPC-157 — TB-500 has been explicitly named in anti-doping cases. Any tested athlete should treat it as a positive test waiting to happen.
Conclusion
TB-500 rests on a genuinely interesting parent protein and a much thinner evidence base for the fragment actually being sold. The gap between "thymosin beta-4 does X in rodents" and "TB-500 does X in humans" is two separate leaps, and both are routinely elided in marketing.
For tested athletes the WADA status alone should settle it.
Sources
Track your own TB-500 protocol
Peppers logs your doses, models your levels from this half-life, tracks your vials and tells you when you will run out. Free on iPhone.
Reference and educational information only. Not medical advice. Nothing here diagnoses, treats, or prescribes, and nothing here is a recommendation to use any compound. The compounds described are research chemicals and are not approved for human consumption. Legal and anti-doping status change — the review date above is when these claims were last checked. Talk to a qualified clinician about anything you intend to take.