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TB-500

Tier 2 · Preclinical
Also known as TB500 · Thymosin Beta-4 fragment · TB4

Tier-1 human evidence is present, but with a critical caveat repeated across sources: nearly all of it was generated with pharmaceutical-grade full-length recombinant thymosin beta-4, not the TB-500 fragment sold in unregulated markets. Tier-1 human RCT/observational sources include the MOTIF cardiac trial, dry eye Phase 2b, Phase 3 ARISE safety trials, neurotrophic keratopathy and cardiac trials2, and an HFpEF plasma-biomarker cohort1. Multiple sources14 emphasize there are no completed human efficacy trials of the TB-500 fragment specifically;15's scoping review found direct TB-500 human evidence limited to a single included study. Lower-tier animal, in vitro, expert-opinion and community claims dominate the remainder.

Half-life
~4 h
Routes
Subcutaneous · Intramuscular · Intravenous · Topical (ophthalmic/dermal in trials) · Sublingual · Oral
Goals
Injury recovery / tissue repair · Wound healing · Anti-inflammatory support · Cardiovascular repair (research) · Joint / musculoskeletal recovery
Cost / mg
$22

How it works

According to the source set, TB-500 is described as a lab-made version of thymosin beta-4, a small peptide that occurs naturally in nearly every human cell. Sources report its core action is grabbing hold of the cell's building-block protein actin, which lets cells move, migrate to injury sites and reorganize — processes tied to wound healing. Across animal and lab studies, sources describe it promoting new blood-vessel growth, calming inflammation and helping tissue repair. Two big cautions run through the sources: sources disagree on whether TB-500 is a short 7-amino-acid fragment or the full 43-amino-acid protein, and almost all human trial data actually used the full-length pharmaceutical protein rather than the fragment vendors sell — so whether the injected fragment itself works is genuinely disputed.

Overview

What sources say TB-500 is

A tier-2 vendor source2 and several others describe TB-500 as a synthetic form related to Thymosin Beta-4 (Tβ4), a naturally occurring 43-amino-acid peptide encoded by the TMSB4X gene on the X chromosome, ubiquitously expressed in nearly all tissues except erythrocytes, with highest concentrations in platelets and wound fluid. A tier-1 review notes Tβ4 is one of the most abundant intracellular peptides in mammalian cells, present at ~0.5 mM in platelets.

The identity of TB-500 is itself contested across the sources. Many sources13 describe TB-500 as a short synthetic fragment — variously a 7-amino-acid acetylated heptapeptide (Ac-LKKTETQ, ~843-889 Da) or 17-residue peptide (~1.9 kDa, one source) corresponding to residues 17-23 of Tβ4. Other sources2,6 describe TB-500 as the full 43-amino-acid peptide (~4,963 Da). A tier-4 source stresses that TB-500 is NOT identical to full-length Tβ4 — different molecular weight, structure, pharmacokinetics and evidence base.

Reported mechanisms

Across tier-1 through tier-4 sources, the described core mechanism is G-actin sequestration regulating cytoskeletal dynamics and cell migration2,3,16. Preclinical/expert sources additionally report angiogenesis via VEGF upregulation, anti-inflammatory signaling through reduced TNF-α, IL-1β and IL-6 and NF-κB suppression, and repair signaling via Akt/PI3K, ERK1/2, p38 MAPK, mTOR, TGF-β, AMPK, HGF and Wnt/β-catenin. A tier-1 review reports that in preclinical models TB-500 retains the G-actin sequestration activity of full-length Tβ4 and produces equivalent cell migration and anti-inflammatory effects — though16 and one source explicitly note this assumed equivalence has not been rigorously validated, and13 reports a March 2024 study in which TB-500 (Ac-LKKTETQ) did not enhance wound healing whereas its metabolite Ac-LKKTE did.

The human evidence base — and its central caveat

Multiple sources14 emphasize that essentially all published human clinical trial data used pharmaceutical-grade full-length recombinant Tβ4, not the TB-500 fragment:

  • Ophthalmic:2 reports a Phase 3 RCT for neurotrophic keratopathy showing 60% healing vs 12.5% placebo (p=0.036 at day 43), but the European confirmatory Phase 3 (SEER-3) failed its primary endpoint; a US SEER-2 trial (N=70) was recruiting. One source14 notes no Tβ4 studies have gone past Phase 2 for FDA approval — an apparent tension in how the landscape is characterized.
  • Cardiac: one source reports the MOTIF trial showed statistically significant improvements in myocardial viability by cardiac MRI post-MI with a favorable safety profile;2 reports a Phase 2 cardiac trial (N=90, NL005) improved cardiac function post-MI.
  • Wound healing:13 reports a European double-blind placebo-controlled study (n=73) in which 0.03% topical TB-500 gave complete healing in ~25% of patients within 3 months and ~1-month acceleration in some, but overall healing rates were not conclusively superior to control — a qualifier vendor sources describing robust efficacy omit.

A tier-3 scoping review15 identified 1772 records and included 80 studies, but reports the evidence base is weighted toward mixed/in vitro designs, remains largely preclinical, and that direct TB-500 human evidence was limited to a single included study. A tier-4 source states there are 0 human studies of the TB-500 fragment versus 6 animal and 3 in vitro studies, describing it as one of the most widely used peptides in the self-experimentation community while being one of the least tested in humans.

Preclinical and single-study signals

Animal/in-vitro sources report accelerated wound re-epithelialization and contraction13, cardiac cell migration/survival and improved function after coronary ligation7, and support for muscle and tendon recovery in rodents. Single, uncorroborated studies within the set report: neuroprotective and cognitive benefits in 5×FAD Alzheimer's mice4, a fetal growth-promoter effect in mice9, corneal repair via a TB500 hydrogel5, tympanic-membrane cell effects in vitro6, and elevated plasma TB4 in HFpEF (especially women1). A tier-2 human observational report8 found that of 4 patients given BPC157+TB4 intra-articular injections, 3/4 (75%) improved in knee pain.

Regulatory and sport status

Sources agree TB-500 is not FDA-approved and is prohibited under WADA — described as S0 unapproved substances (10 context/one source) and Section S2 growth factors13.

What the research shows

150 findings extracted from the 20 sources cited below, strongest evidence first within each group. Every one links to the source it came from.

What human studies found

Based on 7 human trial findings, 11 human study findings, 15 animal findings, 5 in vitro findings and 10 expert opinion findings.

  • human trialPhase 3 RCT for neurotrophic keratopathy showed 60% healing vs 12.5% placebo (p=0.036 at day 43)2

  • human trialEuropean confirmatory Phase 3 trial (SEER-3) for neurotrophic keratopathy failed its primary endpoint2

  • human trialPhase 2 cardiac trial (N=90) completed by Beijing Northland Biotech (NL005) showing improved cardiac function post-MI2

  • human trialPhase 2 RCT trials conducted for dry eye disease2

  • human trialPilot study in STEMI patients (Phase 2 IV, post-PCI)2

  • human trialThe parent molecule has human clinical trial data for ophthalmic and cardiac applications16

  • human trialThymosin beta-4 is the full 43-amino-acid molecule that has been studied in human clinical trials16

  • human studyPlasma TB4 was elevated in HFpEF patients compared with controls (1401 [720-2379] ng/mL versus 985 [421-1723] ng/mL, p<0.001)1

Show 40 more findings

  • human studyPlasma TB4 was not significantly elevated in HFrEF patients compared with controls (1106 [556-1955] ng/mL, p=0.642)1

  • human studyWomen with HFpEF had significantly elevated TB4 compared to controls (1623 [1040-2625] ng/mL versus 942 [386-1891] ng/mL, p<0.001)1

  • human studyMen with HFpEF did not have significantly elevated TB4 compared to controls (1238.5 [586-1967] ng/mL versus 1004 [451-1538] ng/mL, p=1.0)1

  • human studyHazard ratio to all-cause mortality is significantly higher in women with elevated TB4 (1.668, p=0.036), but not in men (0.791, p=0.456) with HF1

  • human studyVenous stasis ulcers trial (small European study)2

  • human studyOf 4 patients who received a combination of BPC157 and TB4 intra-articular injections, 75% showed significant improvement in knee pain, but 25% had no relief8

  • human studyOf 12 patients who received only BPC157 as an intra-articular injection, 11 of 12 patients (91.6%) had significant improvement in knee pain, whereas 1 patient (8.3%) had no improvement8

  • human studyOverall, 14 of 16 patients (87.5%) had relief of knee pain when BPC157 or a combination of BPC157 and TB4 was used8

  • human studyIn a European double-blind, placebo-controlled study (n=73), 0.03% topical TB-500 led to complete healing in approximately 25% of patients within 3 months, typically in small to moderate venous stasis ulcers13

  • human studyIn pressure and stasis ulcers, TB-500 accelerated healing by nearly one month in some patients, but overall healing rates were not conclusively superior to control13

  • animalTB500 ameliorated cognitive impairments in 5×FAD mice as evidenced by improved performance in Morris water maze4

  • animalTB500 improved performance in novel object recognition tests in 5×FAD mice4

  • animalTB500 reduced glial activation in 5×FAD mice4

  • animalTB500 reduced neuronal apoptosis in 5×FAD mice4

  • animalTB500 restored axonal density in the perirhinal cortex of 5×FAD mice4

  • animalTB500 attenuated β-amyloid (Aβ) plaque-associated dystrophic neurites in 5×FAD mice, though hippocampal Aβ burden remained unchanged4

  • animalIn an alkali burn model, the hydrogel significantly accelerated epithelial regeneration, reduced inflammation, and improved corneal barrier function5

  • animalTB4 enhances myocyte survival and improves cardiac function after coronary artery ligation7

  • animalMothers treated with TB4 showed higher cranio-caudal length in newborns compared to control newborns9

  • animalMaternal TB4 treatment was associated with more advanced development of lungs, heart, kidney, cerebral cortex and notochord at histology9

  • animalTβ4 has demonstrated accelerated wound healing, increased angiogenesis, enhanced cardiac repair following ischemic injury, as well as support for skeletal muscle and tendon recovery in rodent models13

  • animalA 2003 study determined that application of Tβ4 in mice accelerated re-epithelialization and wound contraction when compared to saline controls13

  • animalResearch published in March 2024 reported that TB-500 (Ac-LKKTETQ) did not enhance wound healing activity, whereas its metabolite, Ac-LKKTE, did13

  • animalThere is evidence on animals that TB-500 might help heart muscles or other tissues repair more quickly14

  • animalUnapproved peptides like TB-500 demonstrate favorable tissue repair outcomes in animal models17

  • in vitroTB500 significantly attenuated neurite atrophy in Aβ25-35-treated HT22 cells4

  • in vitroTB500 restored cell viability in Aβ25-35-treated HT22 cells and primary cortical neurons4

  • in vitroNap-YpYY-TB500 hydrogel promoted human corneal epithelial cell (HCEC) migration, proliferation, and tight junction recovery in vitro5

  • in vitroTB4 induces tumor metastasis and paclitaxel resistance11

  • in vitroSoluble TB4 peptides produced in cancer cells could be an obstacle to treat tumors with paclitaxel11

  • expert opinionMost published clinical evidence uses pharmaceutical-grade recombinant Tβ4 (e.g., RegeneRx's RGN-259 for eyes, NL005 for cardiac)2

  • expert opinionTB-4 and its derivative TB-500 human orthopaedic data are lacking3

  • expert opinionThere are no controlled human clinical trials for TB-500, and clinical research for thymosin beta-4 is limited and indication-specific13

  • expert opinionThere are no studies of thymosin beta-4 that have gone past Phase 2 for FDA approval14

  • expert opinionStudies conducted on humans with thymosin beta-4 have only been for external use such as dry eye or skin conditions14

  • expert opinionAnimal evidence for TB-500 has not been shown in humans14

  • expert opinionHuman evidence was concentrated in ocular/cornea and wound/skin/soft tissue settings15

  • expert opinionDirect TB-500 evidence was limited to a single included study15

  • expert opinionThe mapped literature supports the popular interest in several repair-related pathways but remains unevenly distributed and largely preclinical, with limited human evidence directly relevant to musculoskeletal applications15

  • expert opinionPreclinical studies on therapeutic peptides including TB-500 are promising but there is a current lack of clinical trials18

How it works

Based on 1 human study finding, 14 animal findings, 31 in vitro findings, 15 expert opinion findings and 5 theoretical findings.

  • human studyThymosin beta-4 (TB4) is an X-linked gene product with cardioprotective properties1

  • animalTB4 can preserve ejection fraction in animal studies of cardiac injury1

  • animalTB-4 and its derivative TB-500 promoted angiogenesis and tissue repair in preclinical models3

  • animalTB500 neuroprotective effects are linked to modulation of apoptosis and synaptic plasticity through regulation of genes including forkhead box B2 (Foxb2) and olfactory receptor, family 2, subfamily K, member 2 (Or2k2)4

  • animalTB4 is expressed in the developing heart7

  • animalTB4 promotes cardiac cell migration and survival7

  • animalIntravenous injections of TB4 alter the morphology of the adult epicardium7

  • animalTB4 changes resemble the characteristics of the embryo7

Show 58 more findings

  • animalTB4 results in increased number of cardiac vessels7

  • animalTB4 alters the gene expression profile typical of the embryonic state7

  • animalTB4 is capable of epicardial progenitor activation7

  • animalTB4 epicardial progenitor activation effect is independent of hypoxic injury7

  • animalTb4-overexpressing transgenic mice showed higher levels of ILK, pGSK3b, and Hh activity compared with wild-type mice10

  • animalTB-500 displays pro-angiogenic properties via several complementary pathways, promoting endothelial cell migration, capillary tubule formation, and stabilization of new vascular networks13

  • animalThe LKKTET sequence is recognized as critical to angiogenic activity and mutations in this sequence greatly diminish the angiogenesis-supporting effects of Tβ413

  • in vitroTB500 modulated expression of apoptosis-related genes in Aβ25-35-treated HT22 cells and primary cortical neurons4

  • in vitroTB500 exhibited anti-inflammatory effects by suppressing lipopolysaccharide (LPS)-induced nitric oxide (NO) production in BV2 microglia4

  • in vitroTB500 reduced expression of pro-inflammatory cytokines in BV2 microglia assays4

  • in vitroTB500 inhibited M1 microglial polarization in BV2 microglia assays4

  • in vitroNap-YpYY-TB500 hydrogel enhanced myofibroblastic differentiation and cytoskeletal reorganization of human corneal stromal fibroblasts (HCSFs) in vitro5

  • in vitroAmong three candidate sequences, Nap-YpYY-TB500 exhibited optimal gelation kinetics, nanostructure, and therapeutic efficacy5

  • in vitroTB-500 (Thymosin beta-4) is a 43 amino acid peptide with regenerative properties in various organ systems6

  • in vitroTB-500 affects the behavior of epidermal and epithelial cells of the tympanic membrane in vitro6

  • in vitroLocal epidermal progenitor cells are the primary targets of TB-500, rather than differentiated cells6

  • in vitroTB4 influences HSC activation through hedgehog (Hh) pathway10

  • in vitroHSC functions declined in TB4 siRNA-treated LX-2 cells10

  • in vitroTB4 suppression down-regulated integrin linked kinase (ILK) and phosphorylated glycogen synthase kinase 3 beta (pGSK-3B)10

  • in vitroTB4 suppression decreased expression of smoothened and GLI210

  • in vitroTB4 CRISPR blocked the activation of primary HSCs10

  • in vitroTB4 interacted with smoothened at the cytoplasm or GLI2 at the nucleus in LX-210

  • in vitroSmoothened suppression in primary HSCs decreased TB4 expression10

  • in vitroThymosin-beta-4 (TB4) is an actin-sequestering peptide that has been detected outside of cells in blood plasma or in wound fluid11

  • in vitroTB4 peptides increase cell survival rate11

  • in vitroTB4 peptides decrease caspase-3 activity11

  • in vitrosiRNA of TB4 inhibited cell viability and augmented caspase-3 activity11

  • in vitroSignificant changes in Bcl-2 phosphorylation were detected by TB4 peptide treatment11

  • in vitroTB4 peptide treatment reduced population in G2/M phase, correlated with decreased expression of cyclin B111

  • in vitroThymosin-beta-4 (TB4) has been known as actin-sequestering protein and functions in tumor metastasis12

  • in vitroTB4-HeLa cells showed a higher growth rate and a lower percentage of basal apoptosis than HeLa cells12

  • in vitroTB4-HeLa cells were more resistant to paclitaxel-induced cell death than HeLa cells12

  • in vitroTB4 transcript expression with paclitaxel treatment was dose-dependently increased in HeLa cells but that was not in TB4-HeLa cells12

  • in vitroSmall interfering RNA (siRNA) of TB4 inhibited HeLa cell growth and enhanced paclitaxel-induced cell death12

  • in vitroBasal ERK phosphorylation was elevated and basal p38 kinase phosphorylation was reduced in paclitaxel non-treated TB4-HeLa cells12

  • in vitroPaclitaxel-resistance of TB4-HeLa cells was overcome by the inhibition of basal ERK activity with PD98059 pre-treatment12

  • in vitroThe inhibition of basal p38 kinase activity with SB203580 pre-treatment attenuated the paclitaxel-induced HeLa cell death12

  • in vitroTB4 induced paclitaxel-resistance through the elevation of basal level of ERK phosphorylation12

  • expert opinionThymosin beta 4 (TB4) is the most abundant member of the beta-thymosin family in humans9

  • expert opinionThe main physiological role of TB4 is the regulation of actin polymerization9

  • expert opinionTB4 is involved in angiogenesis, cell survival, cell migration and fetal development9

  • expert opinionTB-500 is a synthetic heptapeptide (Ac-LKKTETQ) that corresponds to amino acids 17–23 of thymosin beta-4 (Tβ4), a naturally occurring 43–amino acid peptide involved in actin binding, cell migration, angiogenesis, and tissue repair13

  • expert opinionTβ4 regulates cytoskeletal organization by sequestering G-actin, which influences cellular mobility and structural remodeling during wound healing and tissue regeneration13

  • expert opinionTB-500 is a lab-produced peptide that mimics the action of thymosin beta-414

  • expert opinionThymosin beta-4 is a growth hormone that helps tissues like tendons and muscles grow stronger14

  • expert opinionTB-500 is a synthetic peptide derived from thymosin beta-4 that promotes tissue repair through actin regulation, enhanced cell migration, anti-inflammatory signaling, and angiogenesis16

  • expert opinionThymosin beta-4 (Tb4) is a 43-amino-acid peptide found in virtually every human cell16

  • expert opinionTB-500 is centered around the actin-binding domain, specifically the sequence Leu-Lys-Lys-Thr-Glu-Thr (LKKTET at positions 17-22)16

  • expert opinionTB-500 likely carries the same biological activity for tissue repair as the parent molecule, but this has not been rigorously validated across all applications16

  • expert opinionTb4 binds to G-actin in a 1:1 complex, preventing premature polymerization and maintaining a pool of available monomers16

  • expert opinionTB-500 is a wound-healing peptide that promotes angiogenesis, integrin-mediated extracellular matrix remodeling, and fibroblast activation18

  • expert opinionTB-500 acts by modulating molecular signaling networks including PI3K/Akt, mTOR, MAPK, TGF-β, and AMPK pathways18

  • expert opinionThymosin beta-4 (TB4) is an endogenous peptide with protective and regenerative effects in models of cellular and organ injury19

  • theoreticalTB-500 is the commercially available synthetic form of Thymosin Beta-4 (Tβ4), a naturally occurring 43-amino acid peptide encoded by the TMSB4X gene on the X chromosome2

  • theoreticalTβ4 is ubiquitously expressed in nearly all tissues except erythrocytes, with highest concentrations in platelets and wound fluid2

  • theoreticalPrimary intracellular role is sequestering monomeric G-actin to regulate cytoskeletal dynamics, cell migration, and division2

  • theoreticalThymosin-β4 (TB4) is a cellular protein with known extracellular function identified as a hypothetical candidate molecule to examine as a potential mediator in mouse models of osteomyelofibrosis20

  • theoreticalTB4 has a positive effect on osteoblast formation and function20

Dosing

Based on 1 expert opinion finding and 1 anecdotal finding.

  • expert opinionInformation regarding the indications, dosing, frequency, and duration of treatment remains unknown for TB-5003

  • anecdotalPeople who buy TB-500 online typically take it as a powder, pill, or spray, meaning systemic rather than topical use14

How the body handles it

Based on 1 expert opinion finding.

  • expert opinionTB4 release following ex vivo platelet activation can confound clinical measurements19

Safety and side effects

Based on 1 human trial finding and 9 expert opinion findings.

  • human trialTwo Phase 1 IV safety/pharmacokinetic studies conducted with 84 healthy volunteers total2

  • expert opinionTB-500 sold by peptide vendors is a synthetic version but from unregulated sources with variable purity, distinct from pharma-grade products used in trials2

  • expert opinionSignificant research regarding the safety and efficacy of TB-500 is required before definitive recommendations can be made to patients3

  • expert opinionTB-500 is not an FDA-approved drug and is not a lawful dietary supplement ingredient13

  • expert opinionTB-500 has not received FDA approval for any indication, and regulatory agencies have not established its safety or efficacy based on available data13

  • expert opinionTo be considered safe and effective for humans, studies have to go past Phase 3 FDA approval14

  • expert opinionThe assumption that the active fragment retains all properties of the parent molecule is reasonable but has not been rigorously validated16

  • expert opinionRigorous human safety data for unapproved peptides like TB-500 are scarce17

Show 2 more findings

  • expert opinionThere is potential for serious harm to patients from unapproved peptides including TB-50017

  • expert opinionResidual platelets remaining in suspension after centrifugation can confound TB4 clinical measurements19

What people use it for

Based on 2 animal findings, 1 in vitro finding, 11 expert opinion findings, 1 anecdotal finding and 2 theoretical findings.

  • animalTB4 administration during gestation may act as a powerful fetal growth promoter by accelerating development of newborn organs and tissues9

  • animalTb4-overexpressing transgenic mice treated with CCl4 were susceptible to hepatic fibrosis development10

  • in vitroTB-500 promotes tympanic cell migration and proliferation6

  • expert opinionTB-4 and TB-500 remain banned substances in sports3

  • expert opinionTB-500 appears on the World Anti-Doping Agency (WADA) Prohibited List13

  • expert opinionTB-500 was initially designed for veterinary purposes and was used with racehorses and was banned14

  • expert opinionTB4 and TB-500 are widely discussed in tissue healing and musculoskeletal medicine15

  • expert opinionThe most common tissue categories studied were wound/skin/soft tissue, vascular/endothelial, ocular/cornea, and bone15

Show 9 more findings

  • expert opinionDirect musculoskeletal tissue categories such as tendon, ligament, muscle, cartilage, and spine/intervertebral disc were comparatively sparse in the literature15

  • expert opinionTB-500 is most effective for chronic tendinopathies, post-surgical adhesions, and injuries with poor tissue remodeling16

  • expert opinionTB-500 is often combined with BPC-157 for complementary mechanisms16

  • expert opinionTB-500 (thymosin beta-4 fragment) is an unapproved peptide marketed direct to patients17

  • expert opinionTB-500 is used in sports medicine for accelerated injury recovery and performance enhancement17

  • expert opinionTB4 is increasingly measured as a potential plasma or serum biomarker in human cardiovascular, liver, infectious, and autoimmune disease19

  • anecdotalSystemic musculoskeletal use relies on animal studies and clinical observation16

  • theoreticalTB500 has not been previously explored for corneal disease treatment5

  • theoreticalTB-500 could in theory help tissues repair better after injury14

Other findings

Based on 1 in vitro finding and 5 expert opinion findings.

  • in vitroTB500 has the amino acid sequence LKKTETQ5

  • expert opinionThe evidence base for TB4 and TB-500 was weighted toward mixed and in vitro designs15

  • expert opinionMost studies evaluated TB4 rather than TB-50015

  • expert opinionSubstantial intra- and inter-study variability in healthy controls exists19

  • expert opinionLack of protocol standardization in TB4 measurement19

  • expert opinionAssay specificity towards posttranslational modifications can confound TB4 measurements19

Points of contention

Where the evidence is unsettled, thin, or says less than the popular claim — worth knowing before you draw conclusions.

Contested

Whether the injected TB-500 fragment itself works is directly disputed.

Vendor/practitioner sources assume the fragment retains the parent protein's activity (TB-500 and Thymosin Beta-4 Clinical Evidence: What the Human Trial Data Shows | Research Guide | Blackwell BioLabs preclinical, TB-500 (Thymosin Beta-4): A Physician's Complete Guide — Julian Douwes M.D., TB-500 Peptide | Healing & Flexibility), but TB-500 - Status, Risks, and Bans in Sport and Military | Blog reports a March 2024 study finding that TB-500 (Ac-LKKTETQ) did NOT enhance wound healing whereas its metabolite Ac-LKKTE did. TB-500 (Thymosin Beta-4): A Physician's Complete Guide — Julian Douwes M.D. and TB-500 Dosage Guide: Complete Protocol for Safe Administration - Beverly Hills Rejuvenation Center explicitly note the assumption of retained activity has not been rigorously validated.

Limited evidence

Nearly all human clinical evidence used full-length thymosin beta-4, not the TB-500 fragment.

Multiple sources (TB-500: Research Evidence & Safety Profile | PeptideInsight, TB-500: Research, Evidence, Dosing & Safety | Peptidings, TB-500 Dosage Guide: Complete Protocol for Safe Administration - Beverly Hills Rejuvenation Center, TB-500 Dosing Guide: Protocol, Reconstitution & Safety (2026), Superpower, TB-500 for Injury Recovery – Does it Work and is it Safe?, Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians.) emphasize that human trials (Ruff et al. 2010 Phase 1, RGN-259 ophthalmic, SEER neurotrophic keratopathy, MOTIF cardiac, dermal wound-healing) all used pharmaceutical-grade full-length recombinant Tβ4, and that there are no completed human efficacy trials of TB-500 specifically. Thymosin Beta-4 and TB-500 in Tissue Healing ... found direct TB-500 human evidence limited to a single study.

Contested

Wound-healing benefit in humans was not conclusively superior to control.

TB-500 - Status, Risks, and Bans in Sport and Military | Blog reports the European venous stasis ulcer study (n=73) showed ~25% complete healing with 0.03% topical TB-500 and ~1 month acceleration in some patients, but states overall healing rates were not conclusively superior to control — a qualifier that vendor sources describing robust wound-healing efficacy omit.

Other

The same pro-angiogenic mechanism raises oncological safety concerns.

TB-500: Research, Evidence, Dosing & Safety | Peptidings warns the parent protein is overexpressed in several human cancers and that its pro-angiogenic mechanism raises oncological concerns. In vitro studies (Actin-sequestering protein, thymosin-beta-4 (TB4), inhibits caspase-3 activation in paclitaxel-induced tumor cell death., ERK activation by thymosin-beta-4 (TB4) overexpression induces paclitaxel-resistance.) report TB4 induces tumor metastasis and paclitaxel resistance, increases cancer cell survival, and decreases apoptosis. Thymosin beta-4 regulates activation of hepatic stellate cells via hedgehog signaling. reports TB4 promotes hepatic fibrosis in transgenic mice. These contrast with predominantly favorable tolerability reports (TB-500 Half-Life, Sequence, and Dosing: A Physician’s…, Thymosin Alpha-1 vs TB-500: Immune vs Healing | FormBlends, TB-500 (Thymosin Beta-4 Fragment) — Dosing, Side Effects, FDA Status & Research | PeptIQ | PeptIQ).

Limited evidence

No controlled human trial has established TB-500 dosing; protocols come from animal data and community practice.

TB-500 Dosage Guide: Complete Protocol for Safe Administration - Beverly Hills Rejuvenation Center, TB-500 Dosing Guide: Protocol, Reconstitution & Safety (2026), TB-500 (Thymosin Beta-4 Fragment) — Dosing, Side Effects, FDA Status & Research | PeptIQ | PeptIQ and Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians. state dosing ranges (commonly 2–2.5 mg or 2.5–5 mg SC twice weekly during loading) are drawn from animal research and community/anecdotal practice, not validated human prescriptions, and Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians. states indications, dosing, frequency and duration remain unknown.

Single source

Some mechanistic and biomarker findings rest on a single study each.

The HFpEF plasma biomarker findings (Thymosin Beta-4 Is Elevated in Women With Heart Failure With Preserved Ejection Fraction.), the fetal growth-promoter effect in mice (Thymosin beta-4 prenatal administration improves fetal development and halts side effects due to preterm delivery.), the tympanic membrane in vitro work (Thymosin beta-4 - A potential tool in healing middle ear lesions in adult mammals.), the 5×FAD Alzheimer's model results (Thymosin β4-derived peptides alleviate neuroinflammation and neurite atrophy in both in vitro models and in vivo 5 × FAD mice: A potential therapy for memory improvement in Alzheimer's disease.), and the corneal hydrogel study (Alkaline Phosphatase-Triggered Spatiotemporal Repair of Corneal Injury with TB500 Peptide Hydrogel.) each derive from a single study and have not been independently corroborated within the provided sources.

Limited evidence

Plasma TB4 biomarker measurement is confounded and unstandardized.

Sources of variability in quantifying circulating thymosin beta-4: literature review and recommendations. cautions that TB4 as a clinical biomarker suffers from substantial intra- and inter-study variability in healthy controls, lack of protocol standardization, and confounding from residual platelets, ex vivo platelet activation, and assay specificity toward posttranslational modifications.

Sold inside these blends

Commercial products that contain this compound alongside others.

Using it with other compounds

Check a stack
  • GHK-CuComplementary

    May be complementary

    GHK-Cu stimulates collagen/GAG synthesis and ECM remodeling while TB-500 (Thymosin β4 fragment) sequesters G-actin to promote cell migration, angiogenesis and inflammation resolution. Different mechanisms both converge on angiogenesis, integrin/ECM remodeling and NF-κB suppression — a classic complementary regeneration pairing.

    Tier 3Largely anecdotal — commonly discussed
  • ElafinComplementary

    May be complementary

    TB-500 promotes cell migration, angiogenesis and matrix remodeling for wound healing, while elafin protects healing tissue by inhibiting neutrophil proteases and suppressing NF-κB inflammation. Distinct mechanisms both favoring tissue repair.

    Tier 3Largely anecdotal — commonly discussed

    Shares tissue repair · anti inflammatory · NF kB modulation

  • Follistatin-344Complementary

    No documented conflict

    TB-500 promotes tissue repair, angiogenesis and matrix remodeling, while Follistatin reduces muscle fibrosis and inflammatory infiltration and drives hypertrophy. Different mechanisms both favoring healthier muscle/soft-tissue recovery, so they can be viewed as complementary repair agents.

    Tier 4Theoretical — not established

    Shares anti inflammatory · mTOR PI3K

  • HexarelinComplementary

    Worth caution

    Both show cardiac-repair and anti-inflammatory signals through different routes: hexarelin via CD36/PI3K-Akt cardioprotection and NLRP3/NF-κB suppression, TB-500 via actin/cytoskeletal remodeling, angiogenesis and NF-κB suppression. They target the same repair and inflammation-resolution goals through non-overlapping mechanisms, making them a plausible complementary pair for tissue recovery.

    Tier 4Theoretical — not established

    Shares anti inflammatory · NF kB modulation · mTOR PI3K

  • ImunofanComplementary

    No documented conflict

    TB-500 drives cytoskeletal-based cell migration, angiogenesis and NF-κB-suppressing anti-inflammatory repair. This converges with imunofan's reported fibroblast/keratinocyte stimulation and anti-inflammatory cytokine modulation through an entirely different mechanism, supporting a complementary tissue-recovery goal.

    Tier 4Theoretical — not established

    Shares tissue repair · anti inflammatory

  • KPVComplementary

    No documented conflict

    KPV dampens the inflammatory cytokine signal (TNF-α, IL-6, NF-κB), while TB-500 drives the structural side of repair through actin/cytoskeletal dynamics, angiogenesis and cell migration. One quiets inflammation, the other rebuilds tissue — a complementary pairing for wound and mucosal healing.

    Tier 4Theoretical — not established

    Shares inflammation resolution · anti inflammatory · NF kB modulation

  • LL-37Complementary

    May be complementary

    Both promote wound healing, new blood-vessel growth (VEGF), and reduced inflammation, but through distinct mechanisms — LL-37 drives keratinocyte migration and angiogenesis via EGFR/FPR2, while TB-500 regulates actin/cytoskeletal dynamics and cell migration. This makes them a strong complementary tissue-repair pairing.

    Tier 4Theoretical — not established

    Shares tissue repair · angiogenesis · anti inflammatory · VEGF upregulation

  • Palmitoyl Tripeptide-1Complementary

    No documented conflict

    TB-500 (thymosin β4 fragment) promotes cell migration, angiogenesis and anti-inflammatory tissue repair, while Pal-GHK drives collagen and matrix deposition. They converge on the same goal of tissue healing through distinct pathways (actin/cytoskeletal remodeling vs TGF-β collagen synthesis), so they can be viewed as complementary for repair contexts.

    Tier 4Theoretical — not established

    Shares anti inflammatory · tissue repair

  • MatrixylComplementary

    No documented conflict

    TB-500 supports the cell-migration and ECM-remodeling side of repair, while Matrixyl (a topical collagen matrikine) stimulates collagen I/III/IV and fibronectin production. They target different steps of matrix rebuilding \u2014 one systemic, one topical \u2014 so they complement rather than overlap.

    Tier 4Theoretical — not established

    Shares tissue repair

  • GLOWSame mechanism

    Worth caution

    TB-500 (thymosin beta-4 fragment) is already inside GLOW. Adding a separate TB-500 means the same peptide is being administered from two products at once, which is redundant rather than synergistic. Adjust the GLOW dose rather than layering an additional TB-500.

    Tier 3Largely anecdotal — commonly discussed

    Shares tissue repair · angiogenesis · anti inflammatory · NF kB modulation · VEGF upregulation

  • PTD-DBMComplementary

    No documented conflict

    PTD-DBM accelerates wound healing and collagen deposition through Wnt/beta-catenin, while TB-500 promotes cell migration, angiogenesis and matrix remodeling via actin regulation (and also touches Wnt/beta-catenin). The two support tissue and wound repair through largely different mechanisms, a plausible complementary pairing.

    Tier 4Theoretical — not established

    Shares tissue repair

  • BPC-157Complementary

    May be complementary

    BPC-157 and TB-500 drive tissue repair through entirely different molecular targets (VEGF/NO signalling vs. actin regulation), so they are frequently discussed as a complementary healing pair rather than a redundant one.

    Tier 3Largely anecdotal — commonly discussed

    Shares tissue repair · angiogenesis

Safety and side effects

Reported tolerability

Community- and practitioner-level sources describe a generally favorable tolerability profile. A tier-3 comparison source lists common side effects as mild fatigue and injection-site irritation. A tier-2/community source, drawing on 103 community reports, describes TB-500 as generally well-tolerated in research settings with possible mild nausea at higher doses, injection-site redness or discomfort, rare dizziness or lightheadedness, and a potential effect on blood pressure (advising monitoring in hypertensive users).

Human safety data (mostly full-length Tβ4)

One source (via2) reports two Phase 1 IV safety/PK studies were conducted with 84 healthy volunteers total. As with efficacy, these data reflect full-length pharmaceutical Tβ4, not the TB-500 fragment.

Oncological and fibrosis concerns

Several sources raise concerns that contrast with the favorable tolerability reports:

  • A tier-4 source warns the parent protein is overexpressed in several human cancers, and that the same pro-angiogenic mechanism of interest for wound healing raises oncological concerns.
  • Tier-2 in vitro studies report TB4 induces tumor metastasis and paclitaxel resistance, increasing cancer-cell survival and decreasing caspase-3 activity, altering Bcl-2 phosphorylation and reducing the G2/M population11, and inducing paclitaxel resistance via elevated basal ERK phosphorylation (reversed by PD98059)12.
  • A tier-2 study10 reports TB4 promotes hepatic fibrosis in CCl4-treated transgenic mice via hedgehog-pathway activation.

Broader caveats

A tier-2 orthopaedic review3 states human orthopaedic data are lacking, dosing/frequency/duration remain unknown, and that significant safety and efficacy research is required before definitive recommendations can be made. A tier-3 review17 describes TB-500 as an unapproved peptide marketed direct to patients with scarce rigorous human safety data and potential for serious harm. One source13 states regulatory agencies have not established its safety or efficacy. Sources uniformly note TB-500 is not FDA-approved and is prohibited under WADA (see Overview). Reported material properties for reference: molecular weight ~4,963.5 g/mol for full-length Tβ410 versus ~843-889 Da for the fragment4.

Reconstitution and handling

Dosing

No dose has been established for this compound. Multiple sources3 state that no controlled human trial has ever established a TB-500 dose, and that ranges come from animal research and community/anecdotal practice rather than a validated human prescription;3 states indications, dosing, frequency and duration remain unknown. No regulatory label exists, so the figures below are what sources report — not guidance.

  • A tier-3 dosing guide describes the most common dosing as 2–2.5 mg subcutaneously twice per week during a 4–6 week loading phase, then reduced to roughly 2–2.5 mg once every 1–2 weeks for maintenance, with some higher-intensity protocols running 5–7.66 mg per week split across 2–3 injections during loading — and explicitly stresses these are drawn largely from animal research and community practice.
  • A tier-3 protocol source describes community research-use plans of ~2–2.5 mg SC twice weekly during loading (weeks 1–6, ~4–5 mg/week), dropping to 2–2.5 mg once weekly for maintenance (weeks 7–12), with 4–8 week off periods and cycle length commonly 4–12 weeks(vendor claim).
  • A community source describes 2.5–5 mg twice weekly in 4–8 week cycles: a loading phase (weeks 1–4) of 5 mg twice weekly SC, maintenance (week 5+) of 2.5 mg once weekly SC, and an acute-injury protocol of 5 mg twice weekly for 4 weeks.
  • A comparison source cites a typical dose of 2–5 mg SC twice weekly at a reported monthly cost of $150–350;16 reports a 4–6 week loading phase and a cost of 100–300 EUR/month, and notes TB-500 is often combined with BPC-157 (also noted by one source).

No human trial has tested any of these fragment protocols. One source16 describes TB-500 as most discussed for chronic tendinopathies, post-surgical adhesions, and injuries with poor tissue remodeling.

Routes

A podcast14 notes online buyers typically use powder, pill or spray forms.

Reconstitution arithmetic (as reported by sources)

These are calculations about a vial, not dosing guidance:

Store at 2–8°C and use within ~28–30 days.

One source also notes long tissue persistence (the reported basis for twice-weekly dosing) and an athlete detection window of ~30–45 days;2/one source note pharma-grade RGN-259 ophthalmic solution is formulated at 0.1% (13 cites 0.03% topical in the venous-ulcer study).

Sources

Ordered by evidence quality — the strongest first.

  1. Thymosin Beta-4 Is Elevated in Women With Heart Failure With Preserved Ejection Fraction.(opens in a new tab)
    Tier 1PubMed · pubmed.ncbi.nlm.nih.gov · 2017
  2. TB-500 · Compound Monograph | Apotheon(opens in a new tab)
    Tier 2Web · apotheon.io
  3. Injectable Peptide Therapy: A Primer for Orthopaedic and Sports Medicine Physicians.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2026
  4. Thymosin β4-derived peptides alleviate neuroinflammation and neurite atrophy in both in vitro models and in vivo 5 × FAD mice: A potential therapy for memory improvement in Alzheimer's disease.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2026
  5. Alkaline Phosphatase-Triggered Spatiotemporal Repair of Corneal Injury with TB500 Peptide Hydrogel.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2025
  6. Thymosin beta-4 - A potential tool in healing middle ear lesions in adult mammals.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2023
  7. Thymosin beta-4 denotes new directions towards developing prosperous anti-aging regenerative therapies.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2023
  8. Intra-Articular Injection of BPC 157 for Multiple Types of Knee Pain.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2021
  9. Thymosin beta-4 prenatal administration improves fetal development and halts side effects due to preterm delivery.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2021
  10. Thymosin beta-4 regulates activation of hepatic stellate cells via hedgehog signaling.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2017
  11. Actin-sequestering protein, thymosin-beta-4 (TB4), inhibits caspase-3 activation in paclitaxel-induced tumor cell death.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2007
  12. ERK activation by thymosin-beta-4 (TB4) overexpression induces paclitaxel-resistance.(opens in a new tab)
    Tier 2PubMed · pubmed.ncbi.nlm.nih.gov · 2006
  13. TB-500 - Status, Risks, and Bans in Sport and Military | Blog(opens in a new tab)
    Tier 3Web · bscg.org
  14. TB-500 for Injury Recovery – Does it Work and is it Safe?(opens in a new tab)
    Tier 3Web · youtube.com
  15. Thymosin Beta-4 and TB-500 in Tissue Healing ...(opens in a new tab)
    Tier 3Web · mdpi.com · 2026
  16. TB-500 (Thymosin Beta-4): A Physician's Complete Guide — Julian Douwes M.D.(opens in a new tab)
    Tier 3Web · juliandouwes.com · 2026
  17. Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance.(opens in a new tab)
    Tier 3PubMed · pubmed.ncbi.nlm.nih.gov · 2026
  18. Therapeutic Peptides in Orthopaedics: Applications, Challenges, and Future Directions.(opens in a new tab)
    Tier 3PubMed · pubmed.ncbi.nlm.nih.gov · 2026
  19. Sources of variability in quantifying circulating thymosin beta-4: literature review and recommendations.(opens in a new tab)
    Tier 3PubMed · pubmed.ncbi.nlm.nih.gov · 2018
  20. Platelets and osteoblasts: secretome connections.(opens in a new tab)
    Tier 4PubMed · pubmed.ncbi.nlm.nih.gov · 2022

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