TB-500 is one of the most searched research peptides online, and one of the most confusingly named. Here’s what it actually is, what the research covers, and where the evidence stops.
“TB-500” is the name sold online for thymosin beta-4 (Tβ4), a naturally occurring peptide made of 43 amino acids. It is named after the thymus gland, where the thymosin family of peptides was first isolated. The body releases Tβ4 at sites of tissue injury, and it is best known for binding actin, a structural protein cells use to move and change shape.1,2
The vial we carry is supplied as thymosin beta-4. That detail matters, because the name “TB-500” is used for more than one thing.
Online, “TB-500” is used in two different ways: for the full thymosin beta-4 sequence, and for a shorter synthetic fragment built around its actin-binding region (residues 17–23).2 Anti-doping rules treat them together, listing “thymosin-β4 and its derivatives, e.g., TB-500.”4 Research on one does not automatically carry over to the other.
Ask any supplier which one they sell. The only reliable way to tell is identity testing of the batch (mass spectrometry), not the label.
Laboratory and animal work on thymosin beta-4 has looked at cell migration, the growth of new blood vessels, and wound and tissue repair, including in skin, cornea and heart models. Published reviews summarise this work at length.1,2
Human trials exist for thymosin beta-4 itself, but they are narrow. Early-phase studies in healthy volunteers reported no dose-limiting toxicity or serious adverse events, and phase II studies have looked at heart attack, heart surgery, dry eye and chronic skin wounds.2 The best-known late-stage work is an eye drop, RGN-259: in a small phase III trial in neurotrophic keratopathy, 6 of 10 treated patients had complete healing at four weeks versus 1 of 8 on placebo.3
Know what that human data is. It comes from company-linked trials of a pharmaceutical eye drop and similar supervised studies. None of it tested the research-grade vials sold online.
TB-500 is also prohibited in sport: the World Anti-Doping Agency lists thymosin-β4 and its derivatives at all times, in and out of competition.4
Independent testing programs have repeatedly found that a meaningful share of research peptide samples on the market fail on purity, identity, or labelled quantity — most often quantity, where the material is clean but there’s simply less of it than the label claims.
For TB-500, identity matters most: with one name covering both a 43-amino-acid peptide and a short fragment, only independent testing can confirm which one is in the vial. A certificate of analysis (COA) from the manufacturer is a starting point, not proof; independent testing after a batch arrives is the only way to know what is actually in a vial. Our approach is described in how we source and test.
Supplied as a lyophilised (freeze-dried) 10mg vial, reconstituted by the lab with bacteriostatic water before use. Bacteriostatic water is sold separately.
Freeze-dried peptide is far more stable than reconstituted solution. Keep vials away from heat and direct light; refrigerate once reconstituted rather than leaving it at room temperature.
It isn’t a scientific name. It’s the label sellers use for thymosin beta-4 or one of its fragments, and the number is not a dose.
Often described that way, but not always. Some sellers use the name for a shorter fragment. The vial we carry is supplied as thymosin beta-4.
Thymosin beta-4 has been studied in human trials, mostly as an eye drop and in early-phase safety studies. Research-grade vials have not been the subject of clinical trials, and long-term human safety and dosing for them are not established.
No. The World Anti-Doping Agency lists thymosin-β4 and its derivatives, e.g., TB-500, as prohibited at all times.
Keep lyophilised peptide cool, dark, and dry; refrigerate reconstituted solution rather than storing it at room temperature.
Supplied as thymosin beta-4. Or pair it with BPC-157 in the Recovery Stack and save $21.
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