TB-500
A synthetic analogue corresponding to the N-terminal acetylated fragment (Ac-LKKTETQ, residues 17–23) of Thymosin Beta-4, a 43-amino-acid actin-sequestering protein expressed ubiquitously in mammalian cells. Reportedly investigated for tissue repair, wound healing, and musculoskeletal recovery; most community use focuses on injury contexts. The evidence base draws primarily from native Thymosin Beta-4 preclinical research — the two bodies of literature are not directly interchangeable — and human data are sparse; US compounding eligibility was revoked in 2026.
Side effects & risks
TB-500 (a synthetic analogue of Thymosin Beta-4) has not been evaluated in large-scale, randomised controlled trials in humans. No comprehensive human safety profile has been established. The risk profile for human use is, in practical terms, unknown.
In animal studies — primarily rodent and equine models — acute toxicity was not observed at doses studied. Goldstein et al. (2012, Annals of the New York Academy of Sciences, vol. 1269) noted an absence of significant adverse events in animal models used for wound healing research. However, this does not constitute demonstrated human safety.
TB-500 / Thymosin Beta-4 has been studied in a small number of human wound healing trials, notably a Phase II trial in chronic venous stasis ulcers (Guarnera et al., 2010; PMID 20536470). In that trial, no serious adverse events were attributed to the study drug in the treatment group. The study population was small (n=20 in treatment arm) and the follow-up period was limited; a systemic safety profile cannot be extrapolated.
Community reports describe a range of subjective experiences including transient lethargy, mild nausea, and localised injection-site discomfort. These reports are uncontrolled and causality cannot be established. Theoretical concerns exist about any agent that promotes angiogenesis and cell migration in the context of oncological risk. This concern is directly connected to TB-500's proposed mechanism: the same cell migration and angiogenesis via VEGF-related pathways that are hypothesised to underlie wound healing and cardiac repair are the mechanisms through which any theoretical oncological risk would operate. This interaction has not been formally studied in humans, and the magnitude of any such risk is unknown.
TB-500 is not approved for human therapeutic use in any major regulatory jurisdiction. Individuals obtaining it as a research chemical assume an undetermined risk profile.
Evidence summary
Latest studies
Peptides in Regenerative Medicine: A Comprehensive Review of Clinical Applications in Tissue Repair and Chronic Pain Management.
This narrative review gathers what is currently known about several regenerative peptides — BPC-157, thymosin beta-4/TB-500, GHK-Cu and related compounds — in the context of long-term pain management and tissue repair. The authors describe proposed mechanisms and safety profiles, then conclude that human clinical evidence is still thin. Most of these compounds are not FDA-approved for these uses.
Peptide Supplements and Their Therapeutic Applications in Sports Medicine.
Researchers systematically searched the published literature on six peptides marketed for injury recovery and athletic performance - BPC-157, TB-500, CJC-1295, MK-677, ipamorelin and GHK-Cu - and found that about two-thirds of the studies were preclinical, mostly in rats. The handful of human studies were small, often lacked robust control groups, and showed at best modest changes in metabolic bone health measures and degenerative knee pain. The authors also flag documented risks, including congestive heart failure with MK-677 and insulin resistance, and conclude the marketing claims are not yet substantiated by human trials.
Understanding the effects of ciprofloxacin on corneal epithelial cells: a study using electric cell-substrate impedance sensing (ECIS) technology.
This lab-dish study was really about how the antibiotic ciprofloxacin damages corneal cells; thymosin beta-4 was only included as a wound-healing helper on the side.
Community discussion
Community-reported · not verified
These are synthesised observations from public forum discussions. They are community-reported, not clinically verified, and should not inform any health decision. The peptide does not cure, treat, or prevent any condition based on these reports.
“How local is the Wolverine Stack (BPC-157 + TB-500)”
A question thread about the so-called Wolverine Stack of BPC-157 and TB-500, asking whether injecting near an injury produces a localized effect or whether the peptides act systemically regardless of injection site.
“Thymosin alpha-1 vs thymosin beta-4 vs TB-500: why the shared name misleads”
An educational thread untangling the naming confusion between thymosin alpha-1, thymosin beta-4, and TB-500, explaining that the shared thymosin label obscures distinct molecules with different research profiles.
“BPC-157 vs TB-500 (and where KPV fits): what the published record actually says”
A comparison thread reviewing what published research says about BPC-157 and TB-500, and where the smaller peptide KPV fits within that evidence landscape.
“Thymosin alpha-1 vs thymosin beta-4 vs TB-500: why the shared name misleads”
An educational thread explaining why thymosin alpha-1, thymosin beta-4, and TB-500 are frequently conflated, and how the shared thymosin naming masks distinct molecules with different research literatures.
“BPC-157 vs TB-500 (and where KPV fits): what the published record actually says”
A comparison thread walking through the published record on BPC-157 versus TB-500 and situating KPV alongside them, with emphasis on what the evidence does and does not show.
Reported protocols (with caveats)
| USE | ROUTE | COMMON DOSE | FREQUENCY | TYPICAL CYCLE |
|---|---|---|---|---|
| Soft-tissue injury recovery | SC or IM injection | 2–5 mg | 2× weekly (loading); then weekly (maintenance) | 4–6 weeks (loading) |
| General recovery | SC injection | 2 mg | 2× weekly | 4–8 weeks |
Frequently asked questions
- What are the known risks and side effects of TB-500?
- No comprehensive human safety profile has been established for TB-500 as a synthetic compound administered via injection. The only human safety data available is from a small Phase II topical wound healing trial of native Thymosin Beta-4 (Guarnera et al., 2010; PMID 20536470), which cannot be extrapolated to systemic injection use. Community reports describe transient lethargy, nausea, and injection-site discomfort. A theoretical concern exists regarding any pro-angiogenic agent and oncological risk, though this has not been formally studied. The risk profile is, in practical terms, unknown.
- Is TB-500 the same as Thymosin Beta-4?
- No. TB-500 is a synthetic analogue corresponding to an active fragment of the native Thymosin Beta-4 (Tβ4) peptide. The TB-500 fragment is the N-terminal acetylated 17–23 residue sequence (Ac-LKKTETQ; 7 amino acids; PMID 22962027). Native Tβ4 is a 43-amino-acid protein sequenced by Low, Hu, and Goldstein in 1981. Research conducted on native Tβ4 does not automatically apply to TB-500 — they are related but not identical compounds, and the literature should not be conflated.
- How strong is the evidence for TB-500?
- The human clinical evidence is very limited. One small Phase II randomised controlled trial of native Thymosin Beta-4 (topical application) showed a significant wound healing effect (Guarnera et al., 2010; PMID 20536470). A Phase II cardiac trial did not demonstrate significant benefit on primary endpoints. Preclinical (animal) evidence across wound healing, cardiac, and neurological models is more extensive, but animal-to-human translation is not established. For the specific synthetic analogue TB-500, controlled human trial data is absent.
- Is TB-500 legal to buy or use?
- TB-500 is not approved for human therapeutic use in the United States, Australia, Canada, the UK, or most of the EU. The FDA removed TB-500 from its Category 2 compounding list (~April 2026), meaning it can no longer be legally compounded by 503A/503B pharmacies in the US. In most jurisdictions it is sold as a research chemical. It has been banned by multiple equine sports regulatory bodies. Regulatory status varies by country and is subject to change; verify current status with a qualified legal or clinical professional.
- What is TB-500 reported to do in the body?
- Based on research into native Thymosin Beta-4, the compound is hypothesised to facilitate cell migration by modulating actin polymerisation, promote angiogenesis via VEGF-related pathways, and exert anti-inflammatory effects. These mechanisms have been characterised primarily in animal and cell-culture models. The extent to which they operate in humans via injection of the synthetic analogue TB-500 has not been established in peer-reviewed clinical studies.