What is TB-500?

TB-500 usually refers to a synthetic N-acetylated LKKTETQ peptide. The LKKTETQ segment corresponds to amino acids 17-23 of thymosin beta-4, a small endogenous beta-thymosin protein involved in actin binding, cell movement, inflammation signaling, and repair biology. [1][2][4]

The identity boundary matters. Full-length thymosin beta-4 has human studies in ophthalmic, dermal-wound, intravenous safety, and cardiac-development programs, while commercial TB-500 products are usually discussed as the shorter fragment. Those source streams are related, but they are not interchangeable. [6][9][5][1][13]

The practical interest comes from thymosin beta-4 biology: repair literature connects the parent peptide with cell migration, angiogenesis, anti-inflammatory effects, anti-apoptotic signaling, and wound repair. In plain terms, the research question is whether a peptide signal can help injured tissue coordinate movement, blood-vessel support, and remodeling. [4][5][2][3]

In sports and recovery communities, TB-500 is often discussed beside BPC-157. That pairing is common in logs and clinics, but the combination has not been validated as a controlled human recovery stack, and TB-500 has a separate anti-doping and FDA compounding risk profile. [13][14][18]

What TB-500 is investigated for

TB-500 evidence is grouped by practical use case and injectable and topical route context. Each use case separates confidence, human evidence, animal or mechanistic support, and the practical takeaway.

Wound healing and ocular repair

Topical

52% Emerging

Full-length thymosin beta-4 data support wound and ocular repair signals, while route, product, and molecule identity limit transfer to TB-500. [1][6][5]

Human evidence

Human full-length thymosin beta-4 research includes dry-eye studies, local wound studies, and IV safety work. These support parent-peptide translation but do not validate all TB-500 fragment products. [6][7][9][11]

Animal / mechanistic evidence

Corneal and dermal reviews describe thymosin beta-4 effects on epithelial migration, inflammation, apoptosis, angiogenesis, and wound repair. [4][5]

Cardiac tissue repair

Injectable

50% Emerging

Cardiac tissue repair has limited human thymosin beta-4 signal and active TB-500 trial activity, but direct TB-500 fragment benefit for heart disease is unproven. [10][28][21]

Human evidence

A Phase 1/2 TB-500 fragment study is recruiting adults with stable ASCVD and has no posted results. A randomized recombinant full-length thymosin beta-4 STEMI report found an early infarct-area signal, but overall infarct-area differences across the full sample were not significant and the molecule was not TB-500 fragment. [10][28][22]

Animal / mechanistic evidence

Cardiac repair reviews and the recombinant thymosin beta-4 translational study describe cardioprotection, neovascularization, inflammation modulation, apoptosis signaling, and remodeling biology. [21][2][28]

Soft-tissue recovery

Injectable

42% Preliminary

TB-500 has a plausible recovery rationale, but proven injury-repair or performance outcomes in people have not been established. [13][10]

Human evidence

Direct TB-500 human outcome evidence for injury recovery is not established. A recruiting Phase 1/2 study is evaluating safety, tolerability, pharmacokinetics, and exploratory cardiovascular biomarkers, not posted recovery outcomes. [10][13]

Animal / mechanistic evidence

The biological rationale comes from thymosin beta-4 repair literature involving actin, cell migration, angiogenesis, anti-inflammatory effects, and tissue remodeling. [2][5][4]

Tendon and ligament repair

Injectable

34% Limited

Tendon and ligament repair has animal thymosin beta-4 support; controlled human TB-500 fragment efficacy has not been established. [19][1]

Human evidence

No controlled human TB-500 fragment trial has established tendon or ligament repair outcomes. The direct TB-500 trial activity identified here is cardiovascular-biomarker focused, not musculoskeletal injury focused. [10][13]

Animal / mechanistic evidence

A rat medial-collateral-ligament model reported improved histologic organization and biomechanical healing after local thymosin beta-4 treatment, supporting plausibility for ligament repair biology rather than proving fragment efficacy in people. [19]

Alzheimer's-related neuroprotection

Injectable

34% Limited

Alzheimer's-related neuroprotection has cell, organoid, and mouse-model support, but human cognitive or dementia outcomes have not been established. [26][27]

Human evidence

No human TB-500 or thymosin beta-4 clinical outcome trial was identified for Alzheimer's disease or neuroprotection. [10]

Animal / mechanistic evidence

Recent Alzheimer's model studies reported that thymosin beta-4 or thymosin beta-4-derived peptides, including TB500, affected neuroinflammation, neurite atrophy, neuronal survival, and memory-related outcomes in organoid, cell, and 5xFAD mouse models. [26][27]

Muscle repair and recovery

Injectable

32% Limited

Muscle repair has thymosin beta-4 mechanism support, but controlled human TB-500 muscle-recovery outcomes have not been shown. [20][13]

Human evidence

No controlled human TB-500 fragment study was identified for muscle recovery, return to training, strength recovery, or performance outcomes. [10][13]

Animal / mechanistic evidence

A skeletal-muscle regeneration study found thymosin beta-4 expression increased early after injury and that thymosin beta-4 or its sulfoxized form promoted myoblast chemotaxis and wound closure in experimental models. [20]

Reduced inflammation and fibrosis

Injectable

32% Limited

Reduced inflammation and fibrosis are plausible from thymosin beta-4 signaling models, but clinical anti-inflammatory or anti-fibrotic TB-500 outcomes have not been established. [24][25]

Human evidence

No controlled human TB-500 fragment study was identified that establishes reduced inflammation or fibrosis as a clinical outcome. [10][13]

Animal / mechanistic evidence

Thymosin beta-4 literature connects the parent peptide with anti-inflammatory signaling and fibrotic remodeling, including hepatic stellate cell and NLRP3 inflammasome models. [24][25][4]

Hair regrowth

Injectable

30% Limited

Hair regrowth has parent-peptide animal support, but human TB-500 scalp or hair-density outcomes have not been established. [23]

Human evidence

No controlled human TB-500 fragment trial was identified for scalp hair growth, androgenetic alopecia, or hair-density outcomes. [10][13]

Animal / mechanistic evidence

A thymosin beta-4 rodent study reported hair growth in normal and aged animals along with angiogenesis, cell migration, and wound-repair effects. [23]

Evidence snapshot

Overall confidence

Emerging

52%

TB-500 is biologically plausible but not clinically settled. Human experience is stronger for full-length thymosin beta-4 products than for the marketed TB-500 fragment, and the direct TB-500 trial record has no posted outcomes. [6][9][10][13]

Overall confidence is a page-level composite, not an average; it weighs evidence quality, route/molecule match, and practical limitations.

50%

Human evidence

Emerging

Human evidence is strongest for full-length thymosin beta-4 products in dry-eye, wound, IV safety, and cardiac studies. Direct TB-500 fragment human outcome evidence remains limited, with no posted outcomes from the ASCVD biomarker trial. [6][7][9][28][10]

66%

Animal / preclinical

Moderate

Preclinical support is the stronger part of the TB-500 story. Thymosin beta-4 and related fragment studies cover wound, ligament, muscle, fibrosis, hair-growth, cardiac, and Alzheimer's-model biology, but they do not prove fragment outcomes in people. [19][20][23][25][26]

62%

Mechanism support

Moderate

Mechanism support is coherent: thymosin beta-4 biology connects actin handling, cell migration, angiogenesis, anti-inflammatory signaling, anti-apoptotic signaling, and tissue remodeling. Fragment identity and route still limit direct transfer to TB-500 protocols. [2][4][5][1]

Forms & administration

TB-500 is mostly discussed as an injectable fragment protocol, while full-length thymosin beta-4 has been studied as eye drops, dermal gel, and intravenous research products. These are separate administration categories with different evidence, sterility, dose, safety, and regulatory questions. [10][6][11][9][14]

Injectable

Dosing & protocols

The notes below separate published trial design from commonly discussed cosmetic or compounded-use patterns. They are educational context only, not a prescription or product instruction.

Typical Range

Common injectable TB-500 recovery protocols usually use 2-4 mg per dose. [13]

Frequency

Common schedules usually use 2-3 injections per week.

Timing Considerations

Post-workout or evening timing is common. The main practical point is consistency, because recovery notes and training-load changes are easier to compare when timing is stable.

Cycle Length

Common recovery cycles usually run 4-8 weeks before reassessment.

Protocol Notes

Track the rehab plan, pain, range of motion, training load, sleep, injection-site response, and product batch. A peptide log cannot interpret results if several recovery variables change at the same time. [13][14]

What to expect

First week

Small functional changes: less stiffness, steadier soreness, or easier movement during everyday activity and rehab drills. [13]

Weeks 2-4

Easier range of motion, steadier soreness, and better tolerance of rehab loads while the plan stays consistent. [13]

Weeks 4-8

Clearer trend toward less pain, better mobility, and more reliable return-to-training tolerance. [13]

After stopping

Pain, mobility, and return-to-training tolerance should hold steady as rehab load and normal activity continue. [13]

Safety profile

The safety profile is route- and identity-sensitive. Full-length thymosin beta-4 has limited human safety experience in specific trials, but FDA states it has not identified human exposure data for drug products containing thymosin beta-4 fragment (TB-500) and flags immunogenicity, impurity, API-characterization, and unresolved harm concerns. [8][9][14][13]

Common side effects

Injection-site irritation [14][13]

Cautions

Unapproved drug [15]
Sports prohibited [18]
Injectable purity and sterility [14]

What we don't know

The key unknowns are fragment-specific pharmacokinetics, long-term safety, immunogenicity by route, human recovery outcomes, and whether commercial products match studied material. [10][14][13]

Who TB-500 is not for

Route-specific avoid and medical-review notes:

Competitive athletes
Athletes subject to WADA-aligned rules should avoid TB-500 because thymosin beta-4 derivatives including TB-500 are prohibited. [18]
Active infection, surgery, or open wound
Open wounds, post-surgical sites, eye disease, and infections need medical care rather than self-directed TB-500 or thymosin beta-4 product use. [5][4][14]
Pregnancy, breastfeeding, or pediatric use
Safety data are not adequate for elective TB-500 use during pregnancy, breastfeeding, or pediatric care. [14][13]
Cancer or angiogenesis-sensitive conditions
Because thymosin beta-4 biology involves cell migration and angiogenesis, systemic use with cancer or unexplained growth is a theoretical medical-review issue, not a casual recovery decision. [2][5][14]

Drug & supplement interactions

Documented interactions are separated from theoretical or route-specific cautions.

Theoretical interactions

Recovery-plan confounding
Changing rehab intensity, anti-inflammatory medication use, physical therapy, and TB-500 at the same time makes it hard to interpret pain or function changes. [13]
Immune-active medications
Interactions with immunosuppressive or immune-active medications are not established, but the repair and inflammation biology makes medical review important. [4][14]

Pairing notes

Commonly included in these stacks

GLOW Stack

GLOW is a three-component recovery and skin-matrix stack built around BPC-157, TB-500, and GHK-Cu. It is used to frame soft-tissue repair, cell migration, collagen and extracellular-matrix remodeling, and post-procedure skin-support discussions.

BPC-157TB-500GHK-Cu

KLOW Stack

KLOW is a four-component recovery, skin, and inflammation-support stack built around BPC-157, TB-500, GHK-Cu, and KPV. It is used to frame tissue repair, cell migration, skin-matrix remodeling, gut or barrier inflammation, and post-procedure support in one plan.

BPC-157TB-500GHK-CuKPV

Wolverine Stack

The Wolverine Stack is a two-component repair and mobility stack built around BPC-157 and TB-500. BPC-157 supplies the localized repair and cytoprotection rationale, while TB-500 supplies the thymosin beta-4-derived cell-migration and wound-healing rationale. The exact combination lacks controlled human outcome trials.

BPC-157TB-500

Related peptides

BPC-157

Regulatory status

United States

United States: not FDA-approved for human use as a drug. FDA's safety-risk page lists thymosin beta-4 fragment (LKKTETQ), also known as TB-500, under nominated-but-withdrawn bulk drug substances with immunogenicity, impurity, API-characterization, absent human-exposure, and unresolved harm concerns. [15][14]

Route	FDA drug approval	503A compounding
Injectable	Not Approved openFDA Drugs@FDA queries for TB-500 and thymosin beta-4 returned no matching approved drug product. The recruiting TB-500 trial is research activity, not approval. [15][10]	Flagged FDA's safety-risk page lists thymosin beta-4 fragment (LKKTETQ), also known as TB-500, under nominated-but-withdrawn substances and flags immunogenicity, peptide-related impurity, API-characterization, absent human-exposure, and unresolved harm concerns. [14]
Topical	Not Approved No FDA-approved topical, ophthalmic, or dermal thymosin beta-4 or TB-500 drug product was identified in the reviewed openFDA query. Clinical trial listings do not equal FDA approval. [15][12][11]	Not Listed The current 503A PDF review did not identify a topical/local thymosin beta-4 listing separate from the TB-500 fragment safety-risk entry. Local clinical-trial products should not be treated as compounded-drug clearance. [16][14]

Injectable

FDA drug approval

Not Approved

openFDA Drugs@FDA queries for TB-500 and thymosin beta-4 returned no matching approved drug product. The recruiting TB-500 trial is research activity, not approval. [15][10]

503A compounding

Flagged

FDA's safety-risk page lists thymosin beta-4 fragment (LKKTETQ), also known as TB-500, under nominated-but-withdrawn substances and flags immunogenicity, peptide-related impurity, API-characterization, absent human-exposure, and unresolved harm concerns. [14]

Topical

FDA drug approval

Not Approved

No FDA-approved topical, ophthalmic, or dermal thymosin beta-4 or TB-500 drug product was identified in the reviewed openFDA query. Clinical trial listings do not equal FDA approval. [15][12][11]

503A compounding

Not Listed

The current 503A PDF review did not identify a topical/local thymosin beta-4 listing separate from the TB-500 fragment safety-risk entry. Local clinical-trial products should not be treated as compounded-drug clearance. [16][14]

International

International status is product-, route-, and claim-specific. No country-specific therapeutic approval outside the United States is established in the current sources; treat TB-500 as investigational unless a local regulator and product authorization say otherwise. [18]

Sports & competition

Sports competition: prohibited under WADA growth-factor-related rules. The prohibition covers thymosin beta-4 derivatives such as TB-500 and is relevant in and out of competition. [18]

How it works

Thymosin beta-4 biology starts with actin, a structural protein cells use to move and change shape. Repair cells need that movement to cover a wound, remodel tissue, and coordinate local healing. [2][4]

The parent peptide is also discussed in angiogenesis, anti-inflammatory signaling, anti-apoptotic signaling, and scar biology. That creates a coherent repair rationale, especially for local eye and dermal research. [5][3]

TB-500 adds a translation problem: the marketed compound is usually the N-acetylated LKKTETQ fragment. Fragment identity, product purity, and route-specific exposure decide how much parent-peptide biology can be assumed. [1][14]

Research gaps & open questions

What the current literature has not yet settled about TB-500:

Direct TB-500 fragment human outcomes are the biggest gap. The recruiting cardiovascular-biomarker trial can inform safety and pharmacokinetics, but it has no posted results and does not answer injury-recovery efficacy yet. [10]

Full-length thymosin beta-4 and TB-500 fragment evidence need separate pharmacokinetic, safety, and efficacy handling. [1][13]

Product-quality data are needed because sterility, identity, peptide-related impurities, and API characterization can change the safety profile. [14]

Combination-level trials are needed before TB-500 plus BPC-157 can be described as an evidence-backed recovery stack. [13]

Common questions

Is TB-500 the same as thymosin beta-4?

Not exactly. TB-500 usually refers to the N-acetylated LKKTETQ fragment, while many human clinical studies used full-length thymosin beta-4 products. [1][6][13]

Is TB-500 FDA-approved?

No. The reviewed openFDA query returned no matching approved TB-500 or thymosin beta-4 drug product, and FDA lists the TB-500 fragment in compounding safety-risk materials. [15][14]

Does TB-500 have human evidence for injury recovery?

Direct TB-500 fragment evidence for injury recovery is limited. The human literature is stronger for full-length thymosin beta-4 products in other routes and conditions, and one TB-500 trial is recruiting without posted results. [6][10][13]

Is TB-500 banned in sport?

Yes. WADA lists thymosin beta-4 and derivatives such as TB-500 as prohibited, so athletes should not treat research-use or recovery labeling as a loophole. [18]

Is TB-500 plus BPC-157 proven to work better?

No controlled human trial has established the TB-500 plus BPC-157 combination as better than either compound alone. Combination-level efficacy, safety, dosing, and regulatory status need separate review. [13]

Myths & misconceptions

Myth

Any thymosin beta-4 study proves TB-500 works.

Reality

Full-length thymosin beta-4 studies are relevant background, but TB-500 is usually the shorter N-acetylated LKKTETQ fragment. Molecule and route differences matter. [1][13]

Myth

TB-500 is an approved recovery drug.

Reality

It is not FDA-approved for recovery, injury, wound healing, cardiovascular disease, or performance use in the reviewed U.S. database query. [15][10]

Myth

The BPC-157 plus TB-500 stack is clinically proven.

Reality

The stack is common in recovery discussions, but combination-level human evidence, safety, dosing, stability, and regulatory status have not been established. [13][14]

History & discovery

TB-500 entered the peptide market through thymosin beta-4 repair biology and anti-doping attention around an acetylated LKKTETQ fragment. Full-length thymosin beta-4 has a separate clinical-development history in eye, wound, and cardiac programs. [1][2][3]

Research characterized thymosin beta-4 as an abundant actin-binding peptide with roles in cell migration, tissue repair, angiogenesis, inflammation, and scar biology. [2][4]

Anti-doping researchers described TB-500 as a veterinary preparation containing N-acetylated LKKTETQ and developed methods to detect the parent peptide and metabolites in equine samples. [1]

ClinicalTrials.gov lists a recruiting Phase 1/2 study of TB-500 in adults with stable atherosclerotic cardiovascular disease, focused on safety, tolerability, pharmacokinetics, and exploratory cardiovascular biomarkers. [10]

Published research 28 studies

[1]

Doping control analysis of TB-500, a synthetic version of an active region of thymosin beta4, in equine urine and plasma by liquid chromatography-mass spectrometry.

PubMed / Journal of Chromatography A, 2012-11-23. animal.

[2]

Thymosin beta4: a multi-functional regenerative peptide. Basic properties and clinical applications.

PubMed / Expert Opinion on Biological Therapy, 2012-01. review.

[3]

Advances in the basic and clinical applications of thymosin beta4.

PubMed / Expert Opinion on Biological Therapy, 2015. review.

[4]

Thymosin beta 4: A novel corneal wound healing and anti-inflammatory agent.

PMC / Clinical Ophthalmology, 2007. review.

[5]

Thymosin beta4 Promotes Dermal Healing.

PubMed / Vitamins and Hormones, 2016. review.

[6]

Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial conducted using the controlled adverse environment model.

PubMed / Clinical Ophthalmology, 2015. human clinical.

[7]

Thymosin beta4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial.

PubMed / Cornea, 2015-05. human clinical.

[8]

A first-in-human, randomized, double-blind, single- and multiple-dose, phase I study of recombinant human thymosin beta4 in healthy Chinese volunteers.

PubMed / Journal of Cellular and Molecular Medicine, 2021-09. human clinical.

[9]

A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteers.

PubMed / Annals of the New York Academy of Sciences, 2010-04. human clinical.

[10]

TB-500 (Thymosin Beta 4 17-23 Fragment) for Cardiovascular Biomarkers in Stable ASCVD

ClinicalTrials.gov, 2026. clinical trial registry.

[11]

Study of Thymosin Beta 4 in Patients With Venous Stasis Ulcers

ClinicalTrials.gov, 2009. clinical trial registry.

[12]

Comparative Study of Thymosin Beta 4 Eye Drops vs. Vehicle in the Treatment of Severe Dry Eye

ClinicalTrials.gov, 2012. clinical trial registry.

[13]

Safety and Efficacy of Approved and Unapproved Peptide Therapies for Musculoskeletal Injuries and Athletic Performance.

PubMed / Sports Medicine, 2026-04-12. review.

[14]

Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks

U.S. Food and Drug Administration, 2026-04-22. regulatory.

[15]

openFDA Drugs@FDA query for TB-500 and thymosin beta-4

openFDA / U.S. Food and Drug Administration. database query.

[16]

Bulk Drug Substances Nominated for Use in Compounding Under Section 503A of the Federal Food, Drug, and Cosmetic Act

U.S. Food and Drug Administration, 2026-05-14. regulatory.

[17]

FDA Authority Over Cosmetics: How Cosmetics Are Not FDA-Approved, but Are FDA-Regulated

U.S. Food and Drug Administration, 2025-11-20. official guidance.

[18]

2026 Prohibited List: International Standard

World Anti-Doping Agency, 2025. official guidance.

[19]

Thymosin beta4 enhances the healing of medial collateral ligament injury in rat.

PubMed / Regulatory Peptides, 2013. animal.

[20]

Muscle injury-induced thymosin beta4 acts as a chemoattractant for myoblasts.

PubMed / Journal of Biochemistry, 2011. animal.

[21]

Thymosin beta4: A Multi-Faceted Tissue Repair Stimulating Protein in Heart Injury.

PubMed / Current Medicinal Chemistry, 2020. review.

[22]

Safety and Efficacy Study of Thymosin Beta 4 in Patients With Acute Myocardial Infarction

ClinicalTrials.gov, 2022-07-20. clinical trial registry.

[23]

Thymosin beta4 promotes angiogenesis, wound healing, and hair follicle development.

PubMed / Mechanisms of Ageing and Development, 2004-02. animal.

[24]

Potential role of thymosin Beta 4 in liver fibrosis.

PubMed / International Journal of Molecular Sciences, 2015-05-08. review.

[25]

Thymosin Beta 4 Inhibits LPS and ATP-Induced Hepatic Stellate Cells via the Regulation of Multiple Signaling Pathways.

PubMed / International Journal of Molecular Sciences, 2023-02-08. in vitro.

[26]

Thymosin β4-derived peptides alleviate neuroinflammation and neurite atrophy in both in vitro models and in vivo 5xFAD mice: A potential therapy for memory improvement in Alzheimer's disease.

PubMed / International Immunopharmacology, 2026-02-01. animal.

[27]

Thymosin beta 4 as an Alzheimer disease intervention target identified using human brain organoids.

PubMed / Stem Cell Reports, 2025-09-09. animal.

[28]

Recombinant human thymosin beta 4 improves ischemic cardiac dysfunction in mice and patients with acute ST-segment elevation myocardial infarction after reperfusion.

PubMed / Cardiovascular Research, 2025-12-31. human clinical.