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Research information only. Not medical advice. 18+ only. Not FDA-approved for human therapeutic use.

TB-500

Also known as: Thymosin beta-4 fragment, Ac-LKKTETQ, N-acetyl-LKKTETQ, Tβ4 fragment (17-23), Thymosin beta-500

Synthetic peptide fragment (actin-binding / tissue repair peptide); derived from the active site of thymosin beta-4 (Tβ4)

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What it is

TB-500 is the synthetic N-terminal acetylated heptapeptide fragment (Ac-LKKTETQ) corresponding to residues 17–23 of thymosin beta-4 (Tβ4), representing the actin-binding active site of the parent protein (PMID 23084823; PMID 17). In its unacetylated form (LKKTETQ), biological functions include actin binding, dermal wound healing, angiogenesis, and skin repair. TB-500 is claimed to promote endothelial cell differentiation, angiogenesis in dermal tissues, keratinocyte migration, collagen deposition, and decreased inflammation. Reviews describe TB-500 as promoting angiogenesis and tissue repair in preclinical models, and acting via integrin-mediated extracellular matrix remodeling and fibroblast activation (PMID 41490200; PMID 41476424). Metabolic studies found that the primary metabolites are Ac-LK (highest concentration at 0–6 h) and Ac-LKK (detectable up to 72 h), and suggest that previously reported wound-healing activity may be attributable to the metabolite Ac-LKKTE rather than the parent compound itself.

Class: Synthetic peptide fragment (actin-binding / tissue repair peptide); derived from the active site of thymosin beta-4 (Tβ4)

What it's studied for

  • Tendon healing / Achilles tendon repair Animal studies only
    • In a rat Achilles tendon transection model (n=8/group), TB-500 at 60 µg/kg/day IP for 4 weeks produced significantly higher maximum load to failure versus controls (p<0.05), significantly lower Bonar scores (p=0.016) and Movin scores (p=0.017), and altered collagen type I/III distribution consistent with matrix maturat PMID 42542926 Biçer O et al. Joint Diseases and Related Surgery (2026)
  • Wound healing / angiogenesis / tissue repair Mixed
    • In vitro fibroblast wound healing assay: no cytotoxicity found for parent TB-500 or its metabolites; metabolite Ac-LKKTE showed significant wound healing activity compared to control, suggesting that wound-healing activity attributed to TB-500 in the literature may be due to this metabolite. PMID 38382158 Rahaman KA et al. Journal of Chromatography B (2024)
    • Narrative review concludes TB-4 and its derivative TB-500 promoted angiogenesis and tissue repair in preclinical models; human orthopaedic data are lacking. PMID 41476424 Mayfield CK et al. American Journal of Sports Medicine (2026)
    • Review notes TB-500 promotes angiogenesis, integrin-mediated extracellular matrix remodeling, and fibroblast activation; preclinical studies promising but lack of clinical trials noted. PMID 41490200 Rahman OF et al. JAAOS Global Research & Reviews (2026)
    • Narrative review summarizes TB-500's proposed mechanisms in tissue repair and chronic pain; notes evidence in humans is limited and the therapy remains unapproved by the FDA. PMID 42635865 Luansritisakul C et al. Current Pain and Headache Reports (2026)
  • Musculoskeletal recovery and athletic performance Animal studies only
    • Scoping review: 67% of identified publications used preclinical animal models. TB-500 demonstrated unique mechanisms with promising but variable effects on tendon, muscle, bone, and ligament healing in animal models. Human clinical studies were limited, lacking robust controls. Benefits for musculoskeletal recovery rem PMID 42578445 Tewari K et al. American Journal of Sports Medicine (2026)
    • Narrative review: TB-500 demonstrates favorable tissue repair outcomes in animal models, but rigorous human safety data are scarce and there is potential for serious harm. Describes TB-500 as operating in a 'gray market' outside regulatory oversight. PMID 41966639 Mendias CL & Awan TM. Sports Medicine (2026)
  • Healthy aging / gerontology Animal studies only
    • Narrative review identifies TB-500 among peptides with potential applications in tissue repair relevant to aging; non-approved peptides show promising preclinical and limited clinical evidence but lack long-term safety data and systematic validation. PMID 42021992 Mavrych V et al. Frontiers in Aging (2026)

Community-reported dosing

RouteDoseFrequency / DurationPopulation / contextSource tier
Intraperitoneal60 µg/kg/day4 weeksanimalResearch PMID 42542926
Not explicitly stated (post-administration samples collected from horses)Single dose containing 10 mg of N-acetylated LKKTETQSingle administrationanimalResearch PMID 23084823
Subcutaneous10 mg N-acetylated LKKTETQSingle administrationanimalResearch PMID 23318763
subcutaneous injection2.0-2.5 mgtwice per weekbiohackers and athletes seeking accelerated soft-tissue injury recovery[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection2.0-2.5 mgonce per weekbiohackers and athletes post-loading phase or for injury maintenance[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection2.0-2.5 mgonce every 2 weeksbiohackers using TB-500 for anti-aging, general recovery, or injury prevention[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection5.0 mgtwice per weekathletes or bodybuilders with acute or severe soft-tissue injuries[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection5.0 mgonce per weekathletes with moderate-to-severe musculoskeletal injuries[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection750 mcgdailybiohackers preferring daily microdose protocols for systemic distribution[S] Claude Sonnet 4.6 — synthesized from aggregate training data
intramuscular injection2.0-2.5 mgtwice per weekathletes preferring IM administration for localized muscle injuries[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection2.0-2.5 mgtwice per weekbiohackers stacking TB-500 with BPC-157 for synergistic tissue repair[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection2.0 mgonce per weekolder biohackers (40+) using TB-500 for longevity, cardiovascular health, and systemic anti-inflammatory effects[S] Claude Sonnet 4.6 — synthesized from aggregate training data
subcutaneous injection1.0 mgtwice per weekbeginners or cautious biohackers starting with a conservative TB-500 protocol[S] Claude Sonnet 4.6 — synthesized from aggregate training data

Tier key: Research = PMID-cited study · [C] = scraped community source · [S] = model-synthesized from aggregate community reports (softer evidence). How we source.

Safety signals

  • No established human safety profile; rigorous human safety data are scarce and there is potential for serious harm to patients using unapproved TB-500 PMID 41966639
  • Risk of product contamination, manufacturing impurities, and inaccurate dosing from unregulated gray-market sources PMID 42757290
  • Potential for pathological angiogenesis and carcinogenesis associated with unapproved angiogenic peptides including TB-500 PMID 42757290
  • No cytotoxicity observed for parent TB-500 or its metabolites in in vitro fibroblast assays, but biological effects of TB-500 in vivo have not been fully documented PMID 38382158
  • Lack of long-term safety data and systematic clinical validation for TB-500 as a non-approved peptide PMID 42021992

Contraindications

  • No specific contraindications described in the reviewed literature. Use in competitive sports contexts is prohibited under WADA regulations. PMID 41476424

Frequently asked

What is TB-500 and where does it come from?

TB-500 is a synthetic heptapeptide (Ac-LKKTETQ) corresponding to residues 17–23 of thymosin beta-4 (Tβ4), which is the actin-binding active site of the parent protein. It is sometimes referred to as a 'fragment' of thymosin beta-4 (PMID 23084823; PMID 38382158). It is produced synthetically and has been identified as the key ingredient in a veterinary preparation.

What does TB-500 do / what is it used for?

In preclinical models, TB-500 has been studied for promoting angiogenesis, wound healing, collagen deposition, keratinocyte migration, and tissue repair (PMID 23084823; PMID 41476424). An animal study showed improved tendon biomechanics and histopathology after Achilles tendon injury in rats. Importantly, there are no robust human clinical trials supporting these uses, and benefits in humans remain unsubstantiated (PMID 42578445; PMID 41966639).

What dose of TB-500 should I take?

I'm not a medical professional and can't recommend a protocol for you specifically. What research has shown: the only dose reported in a published animal study was 60 µg/kg/day administered intraperitoneally in rats for 4 weeks, and a single equine study used 10 mg subcutaneously. No human dosing data exist in the reviewed literature, and one review explicitly states that 'information regarding the indications, dosing, frequency, and duration of treatment remains unknown'.

Is TB-500 FDA-approved?

No. Reviewed literature consistently describes TB-500 as an unapproved compound. One review states it is among peptides that 'remain unapproved by the U.S. Food and Drug Administration (FDA)', and another describes it as operating in a 'gray market' outside regulatory oversight. Manual verification of current FDA regulatory status is recommended.

Is TB-500 banned in sports?

Yes. Multiple reviewed publications describe TB-500 as a WADA-prohibited substance. One review explicitly states that TB-4 and its derivative TB-500 'remain banned substances in sports'. Anti-doping detection methods for TB-500 in urine and plasma have been developed and validated for both human and equine sports (PMID 26578461; PMID 23084823; PMID 25469748).

Is TB-500 safe for humans?

Human safety data are scarce. Reviewed literature states that 'rigorous human safety data are scarce, and there is potential for serious harm to patients'. Risks associated with unregulated injectable peptides including TB-500 include product contamination, manufacturing impurities, inaccurate dosing, pathological angiogenesis, and carcinogenesis. Non-approved peptides like TB-500 lack long-term safety data and systematic clinical validation. No cytotoxicity was observed in an in vitro fibroblast study, but this does not establish human safety.

Can I combine TB-500 with BPC-157 or other peptides?

I can't recommend combining compounds — that's a prescribing decision. Here's what has been studied individually: one rat study examined TB-500 (60 µg/kg/day IP), BPC-157 (10 µg/kg/day IP), and their combination on Achilles tendon repair. The combination did not confer additional benefit over either agent alone, possibly reflecting convergence on shared downstream pathways. No human combination studies were identified in the reviewed literature.

Where can I buy TB-500?

I don't recommend vendors or sources. Please consult a licensed provider.

Can TB-500 help with my [specific injury or condition]?

I can't suggest treatments for medical conditions. Please speak with a licensed healthcare provider. What the literature shows is that TB-500 has demonstrated tissue repair and tendon healing effects in preclinical animal models (PMID 42542926; PMID 41476424), but human clinical trials are absent and claimed benefits in humans remain unsubstantiated (PMID 42578445; PMID 41966639).

How is TB-500 metabolized and how long can it be detected?

In vitro and rat studies found that the primary metabolite of TB-500 (Ac-LKKTETQ) is Ac-LK, which reached the highest concentration at 0–6 hours after dosing, while Ac-LKK was detectable as a long-term metabolite up to 72 hours in rats. Human kidney microsomes and liver S9 fractions showed high metabolic activity against TB-500 in vitro. In equine anti-doping studies, the parent compound and its metabolite Ac-LK were detected in plasma and urine following a single subcutaneous dose. Human pharmacokinetic data are not available in the reviewed literature.

References

  1. [1] PMID 42542926 — In a rat Achilles tendon transection model (n=8/group), TB-500 at 60 µg/kg/day IP for 4 weeks produced significantly higher maximum load to failure versus contr
  2. [2] PMID 38382158 — In vitro fibroblast wound healing assay: no cytotoxicity found for parent TB-500 or its metabolites; metabolite Ac-LKKTE showed significant wound healing activi
  3. [3] PMID 41476424 — Narrative review concludes TB-4 and its derivative TB-500 promoted angiogenesis and tissue repair in preclinical models; human orthopaedic data are lacking.
  4. [4] PMID 41490200 — Review notes TB-500 promotes angiogenesis, integrin-mediated extracellular matrix remodeling, and fibroblast activation; preclinical studies promising but lack
  5. [5] PMID 42635865 — Narrative review summarizes TB-500's proposed mechanisms in tissue repair and chronic pain; notes evidence in humans is limited and the therapy remains unapprov
  6. [6] PMID 42578445 — Scoping review: 67% of identified publications used preclinical animal models. TB-500 demonstrated unique mechanisms with promising but variable effects on tend
  7. [7] PMID 41966639 — Narrative review: TB-500 demonstrates favorable tissue repair outcomes in animal models, but rigorous human safety data are scarce and there is potential for se
  8. [8] PMID 42021992 — Narrative review identifies TB-500 among peptides with potential applications in tissue repair relevant to aging; non-approved peptides show promising preclinic
  9. [9] PMID 23084823 — Single dose containing 10 mg of N-acetylated LKKTETQ Not explicitly stated (post-administration samples collected from horses) (animal)
  10. [10] PMID 23318763 — 10 mg N-acetylated LKKTETQ Subcutaneous (animal)
  11. [11] PMID 42757290 — Risk of product contamination, manufacturing impurities, and inaccurate dosing from unregulated gray-market sources
  12. [12] PMID 17 — in-prose reference
  13. [13] PMID 26578461 — in-prose reference
  14. [14] PMID 25469748 — in-prose reference
  15. [15] PMID 27569051 — in-prose reference
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