What Is TB-500 (Thymosin β4 fragment)?
TB-500 is a synthetic peptide marketed as a fragment/analogue of the naturally occurring protein thymosin β4, sold for tissue repair, recovery, and “flexibility.” It is used (typically by injection) in the hope of speeding healing of muscle, tendon, and other soft tissue. Like BPC-157, TB-500 is a research chemical — not an approved medicine or dietary supplement — and importantly it is not the same thing as full-length thymosin β4, which is the molecule that has actually reached human trials.
Evidence
Preclinical (animal) research on thymosin β4 and TB-500-type fragments suggests roles in cell migration, angiogenesis, and wound repair, and several animal models report tissue-healing effects. However, direct human clinical trials of the TB-500 fragment specifically are absent — the human data that exists is for the full thymosin β4 molecule (developed pharmaceutically as RGN-259 and related agents), not for the TB-500 fragment sold to consumers. I did not find a verifiable human trial of TB-500 itself in this quick pass; claims about its effects in people therefore rest on animal data and extrapolation from full-length thymosin β4, and should be treated as unproven. (See the separate Thymosin Beta-4 entry for the human trial evidence on the full protein.)
Dosage & Safety
There is no established human dose for TB-500, and no controlled human trials from which to derive one; this page makes no dosing recommendation. TB-500 is not approved by the FDA or other major regulators as a drug or dietary supplement, its fragment is listed among substances flagged as unsuitable/high-risk for compounding, and it is prohibited in sport. Human safety, long-term effects, interactions, and pregnancy/lactation safety are not established. This entry is informational only and is not an endorsement of use.