TB-500
Thymosin β4 Fragment (research chemical; WADA-prohibited)
There are no human efficacy trials of the TB-500 fragment; the supporting science is animal work and the biology of the full thymosin β4 protein. No efficacy claim can be graded, and human safety is unknown.
How confident is BioSignal?
Our overall position, and how sure we are of it across each dimension — including where we are not sure at all.
Limited evidence
There are no human efficacy trials of the TB-500 fragment; the supporting science is animal work and the biology of the full thymosin β4 protein. No efficacy claim can be graded, and human safety is unknown.
Early or sparse human evidence; conclusions remain uncertain.
Human Evidence
No human efficacy trials of the fragment; some formal clinical development exists for the full protein, a different agent.
Mechanistic Plausibility
Thymosin β4 sequesters actin and supports cell migration and tissue repair — demonstrated for the protein, not the marketed fragment.
Research Activity
Full-protein Tβ4 has had clinical programs; the fragment is largely preclinical/anecdotal.
Safety Profile
No human safety data for the fragment; unregulated product.
Consensus
Not approved; explicitly prohibited in sport.
Where the evidence stands today
How mature the science is, what kinds of evidence exist, and — the part nobody else prints — what is still missing.
3/9
steps proven in humans
Evidence-poor
6 steps not demonstrated: Human biomarker / pharmacology · Human safety data · Small human outcome trials · Large human RCTs · Clinical outcomes · Guideline / regulatory support
Guideline / regulatory support
Not shownNot approved; WADA-prohibited.
Clinical outcomes
Not shownNone.
Large human RCTs
Not shownNone.
Small human outcome trials
Not shownNone for the fragment.
Human safety data
Not shownNo controlled human safety data (fragment).
Human biomarker / pharmacology
Not shownNo human data on the fragment.
Animal
ProvenPreclinical repair studies.
Cell / in vitro
ProvenFull-protein studies.
Mechanistic plausibility
ProvenActin-sequestration / cell-migration biology of the full protein.
The bottom line
What we know, what we think, what we don't know — and what would change our mind.
Protein biology, not fragment trials
Thymosin β4 (the full protein) has real tissue-repair biology and has been studied clinically. TB-500 (the short fragment sold as a research chemical) has no human efficacy trials.
Assumed, not tested
The fragment is assumed to share the protein's actions, but that assumption is untested in humans — and the two are not interchangeable.
Everything human
Whether TB-500 does anything in humans, safe dose, long-term safety, and product identity/purity are unknown.
Full-protein work only
Some full-protein Tβ4 clinical development; little rigorous work on the fragment.
What would change the picture
A human randomized trial of the TB-500 fragment would allow the first graded efficacy claim.
The biggest myth
“TB-500 is the same as thymosin β4.”
It is a fragment, not the full protein; equivalence in humans is unproven.
Ask BioSignal
Still have a question about tb-500?
Answers are retrieved from this record and the rest of the knowledge graph — never generated.
Why people take tb-500
Popularity is not evidence — but it is not stupid either. This explains the interest on its own terms.
People search TB-500 for injury and tendon recovery in athletes and gym-goers. Interest is not evidence: the reputation is borrowed from the full thymosin β4 protein, the marketed fragment has no human trials, and it is banned in sport.
If you're here because…
Jump straight to the part of the evidence that answers your question.
Approval, safety and regulatory
What it is approved for, who should be careful, what remains unknown — and the limits of what this evidence can tell you.
Regulatory status
Not Approved
Availability
Unapproved research chemical
Sport (WADA)
Prohibited (S2.3) — confirm at publication
Known safety profile
Unknown in humans for the fragment — no controlled human safety data.
Common issues
- Not characterized in humans
Use caution if
- Everyone (unestablished safety; unregulated product)
- Cancer history (theoretical angiogenic/cell-migration concern)
Long-term unknowns
All long-term safety.
Limits of this evidence
Efficacy evidence is animal/full-protein; human fragment safety is a genuine unknown.
Full regulatory and sport detail
- Regulatory approval
- None (no approved therapeutic for the TB-500 fragment).
- Approved indication
- None.
- Investigational
- The full thymosin β4 protein has had clinical programs; the marketed fragment has not.
- Research chemical
- Yes — sold outside pharmaceutical quality control.
- Compounding
- Not applicable / not an approved compounding substance.
- Sport (WADA)
- Prohibited under S2.3 (peptide hormones / growth factors), in- and out-of-competition — confirm at publication.
- Publication note
- Re-confirm regulatory and anti-doping status against primary sources at publication.
Demand, separated from evidence
Every claim people make about this, counted against what the evidence actually showed.
BioSignal evaluated 4 popular claims about tb-500.
Here is where each one landed — including the claims of harm, where “not established” is reassuring rather than damning.
- Insufficient evidence
- 1
- Not established
- 3
Popularity is not evidence. This is simply a count of every claim BioSignal evaluated on this page, sorted by what the evidence actually showed — the full reasoning behind each verdict is in the Evidence Review below.
Insufficient evidence
- TB-500 heals injuries in people.
Not established
- TB-500 is the same as thymosin β4.
- TB-500 is safe.
- TB-500 is allowed for athletes.
The evidence review
Every claim with the reasoning behind its verdict, the doses actually studied, where scientists agree and disagree, and the questions still open.
What people claim
Every popular claim, with BioSignal’s verdict and how confident we are in it. The verdicts are always visible; open any claim to read the evidence behind it.
TB-500 heals injuries in people.Insufficient evidenceLimited evidence
No human efficacy trials of the fragment; evidence is animal work and full-protein biology.
TB-500 is safe.Not establishedCaution
No human safety data; unregulated product of unknown composition.
TB-500 is allowed for athletes.Not establishedHigh confidence
Thymosin β4 and its derivatives (including TB-500) are prohibited by WADA (class S2.3) at all times.
Doses used in human studies
What was actually given to participants in the research. These are descriptions of studies, not recommendations.
—
- Intervention
- TB-500 fragment
- Dose
- None
- Duration
- —
- Outcome
- —
- Notes
- No controlled human efficacy studies of the fragment. Market 'protocols' are not evidence-based.
Where scientists agree — and don’t
Agreed
- Thymosin β4 (full protein) has genuine repair biology and has entered clinical development
Debated
- Whether the marketed fragment reproduces the protein's effects
- The reliability of anecdotal athlete reports
Unknown
- All human efficacy, dose, and safety questions for the fragment
What remains unknown
- Is there any human efficacy of the TB-500 fragment?
- What is a safe human dose and the short/long-term safety?
- Do fragment and full protein behave equivalently in humans?
Questions people actually ask
Is TB-500 the same as thymosin beta-4?
No. TB-500 is a short fragment of the full thymosin β4 protein. The full protein has real repair biology and some clinical development, but the marketed fragment has no human trials and is not proven to behave the same way.
Is TB-500 banned in sport?
Yes — thymosin β4 and its derivatives, including TB-500, are prohibited by WADA at all times.
Practical takeaways
- TB-500 (the fragment) has no human efficacy trials — its reputation borrows from the full protein.
- Human efficacy and safety are unknown; BioSignal cannot recommend it.
- It is not an approved drug and is sold as an unregulated research chemical.
- It is banned in sport by WADA — a positive test carries serious consequences.
- For recovery, rely on the evidence-based basics (sleep, protein, loading, time), not an unproven, prohibited peptide.
How it works
The mechanism comes last on purpose. A compelling explanation of how something might work is the easiest part of the story to tell, and the part most likely to outlive the evidence for it.
How we found out
2005 — Tβ4 biology review
Actin-sequestration and tissue-repair functions of the full protein.
2010 — Tβ4 clinical-application review
Structure/function supporting clinical development of the full protein.
Ongoing
No human efficacy trials of the TB-500 fragment; standing WADA prohibition.
References
Verified sources. BioSignal does not print a citation it has not checked.
- 01
Thymosin beta4: actin-sequestering protein moonlights to repair injured tissues
Trends Mol Med 11(9):421-429 · 2005
- 02
Thymosin beta4: structure, function, and biological properties supporting current and future clinical applications
Ann N Y Acad Sci 1194:179-189 · 2010
Version history
1.0
Initial review-hardened record (Experimental; Insufficient/Caution; WADA-prohibited). Review cadence: Semiannual.
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