TB-500 (Thymosin Beta-4)
A synthetic fragment related to Thymosin Beta-4; not FDA-approved for human use.
What it is
TB-500 is a synthetic fragment of thymosin beta-4, a naturally occurring protein involved in cell migration and tissue repair. Like BPC-157 — its constant companion in 'healing stack' marketing — it is not an approved drug in any country.
The evidence base is animal models and laboratory work; thymosin beta-4 itself has seen small human studies in other contexts, but TB-500 as sold online has no published controlled human trials. It also appears on sport anti-doping prohibited lists, which matters for tested athletes.
What researchers have actually studied it for
Wound healing and tissue-repair models in animals; the parent protein has limited early human research in unrelated contexts.
How it works
Thymosin beta-4's day job is binding actin — the protein cells use to move — which makes it central to cell migration into wounds. The TB-500 fragment carries the actin-binding region, and animal models credit it with promoting cell migration, blood-vessel formation and reduced scarring at injury sites.
Where it came from
Thymosin beta-4 came out of 1960s–70s thymus research; its wound-healing thread produced legitimate trials of the full protein (eye injuries, pressure ulcers, cardiac repair) with mixed results that never reached approval. The TB-500 fragment took a different road: veterinary use in racehorses, then the human gray market.
What the research record actually contains
- Animal wound, cardiac and corneal models for thymosin beta-4 and its fragments.
- Small human trials of full-length thymosin beta-4 in unrelated indications — mixed, never approved.
- No published controlled human trials of TB-500 itself.
- Anti-doping positives confirm real-world athletic use, not efficacy.
What's known about risks
No human safety characterization exists for the fragment. The same cell-migration and angiogenesis biology behind the healing hypothesis is biology worth respecting — promoting cell movement is not inherently benign — and gray-market sourcing stacks unverified contents on top.
Where it stands legally
Unapproved everywhere; no compounding pathway; research-chemical channel only. Explicitly prohibited in equine and human sport.
Worth asking a licensed provider
- 1.Does any human evidence connect this fragment to my injury, or only animal models?
- 2.If healing support is the goal, which evidence-backed protocols should we exhaust first?
- 3.Am I subject to any drug testing where this would end my season?