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What it is
A synthetic peptide corresponding to a fragment of thymosin beta-4, a naturally occurring actin-binding protein involved in cell migration and wound repair. What is sold as TB-500 is the fragment, not the full protein studied in most of the literature.
How it is proposed to work
Actin sequestration influencing cell migration, angiogenesis and inflammatory signalling during repair. Whether the fragment reproduces the full protein's activity in humans is an open question and a fairly fundamental one.
Approved medical uses
None. TB-500 has no approved human medical indication in the jurisdictions we track. Any use is outside an approved label.
Human research
Each entry states what the study found and, separately, what it cannot show.
No adequate published human research. This absence is the reason for the evidence grade above — it is not a gap we can fill with animal data.
Preclinical research
Animal and laboratory work. Useful for generating hypotheses; it cannot establish that something works in people.
- Animal2003
Impaired-healing dermal wound models: diabetic and aged mice
Finding. In full-thickness dermal wounds, thymosin beta-4 given in phosphate-buffered saline or a hydrogel formulation accelerated repair across more than one impaired-healing model. In db/db diabetic mice, wound contracture and collagen deposition were significantly increased with treatment, but keratinocyte migration showed no difference — all diabetic animals showed almost complete coverage of the wound at 8 days. In 26-month-old aged mice, whose healing was significantly delayed, treatment increased keratinocyte migration, wound contracture and collagen deposition. A seven-amino-acid synthetic peptide duplicating the actin-binding domain, LKKTETQ, promoted repair in the aged animals comparably to the parent molecule. The hydrogel formulation generally showed wound-healing activity similar to thymosin beta-4 in saline.
Limitation. Rodent wound models — mice, with normal rats for the parent protein — and the abstract reports no animal counts. The peptide was given in saline or a hydrogel formulation for a skin wound; the abstract describes no systemic injection, which is how TB-500 is actually used for musculoskeletal injury. As abstracted, the seven-amino-acid actin-binding fragment was tested in the aged mice only; everything else here is the full-length parent protein. No cardiac outcomes and no human outcomes.
- Animal2014
Dermal burn wound healing in diabetic mice
Finding. In db/db diabetic mice given a deep second-degree burn on the dorsal skin, thymosin beta-4 injected intradermally near the burn wound, twice a week for two weeks, improved wound-healing markers — wound closure, granulation and vascularization — and reduced levels of the receptor for advanced glycation end products (RAGE) during the healing period. The authors frame this as a potential therapy for the impaired burn-wound healing associated with diabetes.
Limitation. An animal study: diabetic mice, thymosin beta-4 itself rather than the fragment sold commercially, and repeated local intradermal injection near the wound rather than systemic dosing. The abstract reports healing markers qualitatively, with no effect sizes and no total animal count, and the model is a dermal burn — it says nothing about musculoskeletal injury in humans. The authors note that earlier thymosin beta-4 wound-repair work had been limited to mechanical damage and dermal impairment.
Potential safety concerns
- SeriousInsufficient
No adequate human safety dataset. Absence of reported harm reflects absence of systematic study, not a clean record.
- SeriousPromising
Independent testing has repeatedly found mislabelled and impure peptide products in this category.
- CautionInsufficient
Effects on angiogenesis and cell migration are the mechanism it is bought for and also the reason its oncological profile would need study before any reassurance is possible. That study does not exist.
Known interactions and contraindication considerations
- Not characterised in humans.
This list is not exhaustive and is not a substitute for a clinician reviewing your full medication history.
Regulatory status
Status is shown per jurisdiction and is accurate only as of the date stated. Where a compound is approved, the approval is bound to a specific formulation, manufacturer and indication — shown in the detail column.
| Jurisdiction | Standing | Detail |
|---|---|---|
United States FDA | Not approved as of 24 Jul 2026 | Not approved. Has appeared in compounding-category discussion, which is not an approval. Prohibited in sport. |
European Union EMA | Unapproved / investigational as of 1 Jun 2026 | No marketing authorisation. |
India CDSCO | Unapproved / investigational as of 1 Jun 2026 | New-drug pathway would apply. Not approved for human use. |
How it is being used
What the grey community actually runs, the reasoning they give, and our read on whether it follows from known biology. This is observation, not evidence, and not a recommendation.
Tissue repair, usually stacked with BPC-157
What is run
Less frequent than BPC-157 — typically a loading pattern of a few administrations weekly, then reduced.
Their mechanistic reasoning
That actin sequestration promotes cell migration and angiogenesis at injury sites, complementing BPC-157's growth-factor effects through a separate pathway.
Reported in the community’s own terms. Not our position.
Stacked with
- BPC-157—The near-universal pairing, on complementary-pathway reasoning.
Regimen shape
- Dose
- figure withheld
- Scale
- Milligram-scale
- Route
- Subcutaneous injection
- Frequency
- Two or three times weekly, reducing after an initial period
- Timing
- No consistent convention
- Duration
- Multi-week blocks
Our read
The pathway distinction is real and the complementarity argument is coherent. Two problems sit underneath it. The animal evidence largely studies the full thymosin beta-4 protein, while what is sold is a fragment — whether the fragment reproduces that activity in humans is unresolved and fairly fundamental. And no adequate human trial exists for either. Combining two untested compounds does not produce a tested one.
What the community reports
The comparison is between how sure the community is and how much is actually known — evidence strength, not direction. A compound can have solid research that came out negative.
Believed in largely by association with BPC-157 rather than on its own reports. Very few people run it alone, so its reputation is effectively borrowed.
Commonly reported as helping
- Improved recovery when added to BPC-157
- Reports of benefit in more systemic or widespread injury
Also reported, when it goes wrong
- Hard to attribute anything to it specifically
- Lethargy reported by some
- Cost, given the amounts used
Why these reports can mislead
Almost every report comes from someone running it alongside BPC-157, so the compound has essentially no independent evidence base even at the anecdotal level. Its reputation is inherited rather than earned.
Direct quotations are not published here yet. We will only carry verbatim reports once they are sourced, dated and checked — an unattributed quote is a testimonial, and testimonials are exactly what this section exists to replace.
Watch for, in this use specifically
- What is sold is a fragment, not the protein most of the cited research studied.
- Angiogenesis and cell migration are the mechanism and also the reason the oncological profile would need study before anyone can offer reassurance.
- Prohibited in sport.
Active clinical trials
No registered trials currently tracked for TB-500.
What remains unknown
The questions that would change our assessment if they were answered.
- Does the commercial fragment reproduce the parent protein's activity at all?
- Does systemic administration deliver anything to an injured site in humans?
- What would repeated stimulation of angiogenesis and cell migration do over years?
References
- 1.Philp D, Badamchian M, Scheremeta B, Nguyen M, Goldstein AL, Kleinman HK. Thymosin beta 4 and a synthetic peptide containing its actin-binding domain promote dermal wound repair in db/db diabetic mice and in aged mice. Wound Repair Regen. 2003 Jan-Feb;11(1):19-24.PMID 12581423doi
- 2.Kim S, Kwon J. Thymosin beta 4 improves dermal burn wound healing via downregulation of receptor of advanced glycation end products in db/db mice. Biochim Biophys Acta. 2014 Dec;1840(12):3452-9.PMID 25230158doi
Editorial change history
When we change a grade or a regulatory note, we log it here rather than editing quietly.
Dossier created. Note added distinguishing the commercial fragment from the full protein studied in most of the cited literature.
Spotted something wrong? Tell us — we publish corrections.