TB-500 / Thymosin Beta-4
Also known as: TB-500, thymosin beta-4, Tβ4
A naturally-occurring repair peptide with interesting lab biology — and no controlled human evidence for the recovery claims.
What it is
TB-500 is a peptide marketed for recovery and tissue repair, closely tied to thymosin beta-4, a naturally-occurring repair-related peptide. It is often paired with BPC-157 in marketing, and shares the same core problem: real lab biology, no controlled human evidence for the fitness claims.
Composition
Thymosin beta-4 (Tβ4) is a naturally-occurring 43-amino-acid peptide. “TB-500” is the name commonly used for a synthetic version — often described as an active fragment — sold as a research chemical. The two names are used loosely and are not always the identical molecule.
Proposed mechanism
Thymosin beta-4 regulates actin, a protein central to how cells move, migrate and rebuild tissue. Through that role it is proposed to support wound healing, blood-vessel formation and cell migration to injured areas.
Claimed benefits
Faster injury recovery, reduced inflammation, improved flexibility and tissue repair.
What the evidence shows
Preliminary· animal data only. The mechanism is real and thymosin beta-4 has been studied in humans for specific medical conditions (for example certain eye-surface and cardiac indications). But the recovery-and-repair claims for athletes rest on cell and animal studies plus mechanistic reasoning — there are no controlled human trials showing it improves athletic recovery. So that use is unproven, not disproven; the evidence simply isn’t there yet.
Legal & regulatory status
Not an approved medicine for fitness use. Sold as a research chemical. TB-500 / thymosin beta-4 is prohibited in sport under the WADA code (growth factors and related peptides) at all times.
Known risks & unknowns
Long-term safety for fitness use is not established. Because Tβ4 influences cell migration and blood-vessel growth, there are theoretical concerns around anything that could promote unwanted tissue growth — concerns that human safety trials for this use have not addressed. Research-chemical products add the usual purity and contamination unknowns.
Sources
Frequently asked questions
- What is thymosin beta-4?
- It is a naturally-occurring peptide involved in regulating actin, a protein central to how cells move, migrate and repair. 'TB-500' is the name commonly used for a synthetic version (or fragment) sold as a research chemical.
- Does TB-500 speed up recovery in people?
- The recovery and tissue-repair claims come from cell and animal studies plus mechanism. Thymosin beta-4 has been studied in humans for specific medical conditions (such as certain eye and heart indications), but there are no controlled trials showing it improves athletic recovery — so that use is unproven.
- Is it safe?
- Long-term safety for fitness use is not established, and 'research chemical' products carry the usual purity and contamination unknowns. Treat any online supplier's safety assurances with scepticism.
- Is TB-500 banned in sport?
- Yes. Thymosin beta-4 / TB-500 is prohibited under the WADA code (growth factors and related peptides) at all times.
Related compounds
- BPC-157 — Preliminary
An evidence-tiered explainer on BPC-157: a synthetic peptide heavily marketed for tendon and gut healing, whose supporting evidence is almost entirely animal studies, with no controlled human trials.
Written and reviewed by Mathew Beale — MSc Biotechnology, University of Reading.
Last reviewed: