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Moderate EvidencePeptide

TB-500

Thymosin Beta-4 Fragment

Tissue Repair Peptide

Last updated: December 2025
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Evidence Level: Moderate Evidence

Some human data, strong animal studies, plausible mechanism

Regulatory Status: Not FDA approved. Banned by WADA. Sold as "research chemical" in gray market.

TB-500 is a synthetic peptide derived from thymosin beta-4 (Tβ4), a naturally occurring protein found in nearly all human cells. It plays a critical role in tissue repair, cell migration, and new blood vessel formation. Like BPC-157, it's popular in biohacking circles for injury recovery, but the human evidence is even more limited.

How It Works

Thymosin beta-4 is one of the most abundant proteins inside cells, primarily involved in regulating actin (a building block of the cellular skeleton). TB-500 is a synthetic fragment that appears to retain the key regenerative properties.

Key mechanisms:

Cell migration: TB-500 promotes the movement of cells to injury sites, essential for wound healing and tissue repair.

: Stimulates new blood vessel formation, improving nutrient and oxygen delivery to damaged tissue.

Anti-inflammatory: Reduces inflammatory markers like TNF-α and IL-1β, potentially speeding recovery.

Anti-fibrotic: May reduce scar tissue formation, promoting more functional healing.

Actin regulation: Helps reorganize the cellular skeleton, enabling damaged cells to repair and migrate.

The systemic nature of TB-500 (it affects the whole body rather than just the injection site) distinguishes it from more localized peptides like BPC-157.

Evidence by Outcome

Each claim below is rated using a GRADE-aligned five-tier system. Same molecule, different outcomes, different evidence.

Evidence at a glance

How we grade

Want to see how this compares to every other peptide? Browse the full evidence matrix, where every graded claim is grouped by outcome and sorted by certainty.

Tissue repair / healingPreclinical certainty

Accelerates healing of muscle, tendon, and ligament injuries when injected.

Population: No human population has been studied for this use. Evidence is from animal models.

Why this rating

There are no human efficacy trials of injected TB-500 for musculoskeletal injury. There is a second, easily missed problem: TB-500 is a short fragment (LKKTETQ) of thymosin beta-4, while essentially all of the human clinical work, including the dry eye and ulcer trials, used full-length recombinant thymosin beta-4. Vendors routinely cite the full-length trials as evidence for the fragment. They are different molecules, given by different routes, for different conditions.

Supporting studies

Reviewed September 2026· Designing Longevity EditorialHow we grade
Tissue repair / healingLow certainty

Full-length thymosin beta-4 eye drops reduce discomfort and corneal damage in dry eye disease.

Population: Adults with moderate to severe dry eye disease, treated with topical full-length Tb4 (not TB-500)

Why this rating

This comes from a real randomized, double-masked, phase 2 trial of 72 participants, which is far better evidence than anything supporting the injectable fragment. It is graded low rather than moderate because it is a single small phase 2 trial that has not been confirmed by a , and because it is highly indirect evidence for how TB-500 is actually sold: a different molecule, a different route, and a different condition.

GRADE downgrade factors applied

  • Indirectness: Studied population, intervention, comparator, or outcome differs from the question being answered.
  • Imprecision: Wide confidence intervals or small sample size, the estimate could be substantially different.

Supporting studies

Reviewed September 2026· Designing Longevity EditorialHow we grade
Tissue repair / healingLow certainty

Speeds healing of chronic pressure and venous stasis ulcers.

Population: Adults with chronic pressure or venous stasis ulcers, treated with topical full-length Tb4 gel

Why this rating

Phase 2 programs reported faster mean healing times, but the trials were underpowered and the differences did not reach statistical significance, and the results are company-reported rather than published in full. As with dry eye, this used full-length thymosin beta-4 applied topically, not the injected TB-500 fragment.

GRADE downgrade factors applied

  • Imprecision: Wide confidence intervals or small sample size, the estimate could be substantially different.
  • Indirectness: Studied population, intervention, comparator, or outcome differs from the question being answered.
  • Publication bias: Suspicion that negative or null results were not published, inflating apparent effect.

Supporting studies

  • RegeneRx phase 2 programs in pressure ulcers and venous stasis ulcersRandomized Controlled Trial
    n=143

    Mean healing time about 39 days versus 71 on placebo in venous stasis ulcers, not statistically significant at this sample size.

Reviewed September 2026· Designing Longevity EditorialHow we grade

Potential Benefits

  • Animal studies show accelerated wound healing and tissue repair
  • May reduce inflammation and promote
  • Systemic effects, doesn't require injection at injury site
  • Research suggests cardiac tissue regeneration potential in animal models
  • Generally well-tolerated in Phase I human safety trials (up to 1260mg IV)
  • May help with flexibility and reduce muscle adhesions

Risks & Considerations

  • No FDA approval, buying from unregulated gray market sources
  • Extremely limited human clinical trial data for musculoskeletal use
  • Quality and purity vary wildly between vendors
  • Banned by WADA, will cause positive doping test
  • Theoretical cancer concern (promotes cell migration and )
  • Long-term effects completely unknown
  • May interact with blood thinners or affect clotting
  • Systemic effects mean you can't control where it acts

Dosing Information

There is no official dosing since TB-500 is not approved for human use. The following reflects common practices in the biohacking and veterinary communities.

  • •Loading phase: 2-2.5mg twice weekly for 4-6 weeks
  • •Maintenance phase: 2-2.5mg once weekly or every 2 weeks
  • •Subcutaneous injection (anywhere, it's systemic)
  • •Some users combine with BPC-157 ("healing stack")
  • •Typical cycle: 4-12 weeks depending on injury
  • • with , store refrigerated

Need to mix this from a vial?

Use our reconstitution calculator to get the exact insulin syringe units to draw.

Practical Tips

  • 1Unlike BPC-157, injection location doesn't matter, TB-500 is systemic
  • 2Often stacked with BPC-157 for complementary mechanisms
  • 3Source quality is critical, demand third-party COAs
  • 4Start with loading phase for acute injuries, maintenance for ongoing support
  • 5Not a replacement for proper rehabilitation and physical therapy
  • 6If you compete in tested sports, this will trigger a positive test

Key Research

Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial

Clinical Ophthalmology, 2015

A double-masked, phase 2 trial of topical full-length thymosin beta-4 eye drops in moderate to severe dry eye reported reductions in ocular discomfort and corneal staining. Note this used full-length recombinant Tb4, not the TB-500 fragment, and was applied to the eye rather than injected.

View Study

De novo cardiomyocytes from within the activated adult heart after injury

Nature, 2011

Thymosin beta-4 priming enabled adult mouse heart progenitor cells to form new cardiomyocytes after injury, alongside new blood vessel recruitment.

View Study

RegeneRx phase 2 programs in pressure ulcers and venous stasis ulcers

Company-reported phase 2 results

Topical full-length Tb4 gel was reported to shorten mean healing time in venous stasis ulcers (about 39 days versus 71 on placebo), but the trials were too small for the difference to reach statistical significance.

Looking into TB-500?

Learn about sourcing and working with a knowledgeable provider.

Compare with BPC-157Peptide Safety Guide

Always consult a healthcare provider before starting any treatment.

Frequently Asked Questions

What is the difference between TB-500 and BPC-157?

TB-500 and BPC-157 both promote healing but work differently. TB-500 is systemic, it doesn't matter where you inject it because it affects the whole body through cell migration and blood vessel formation. BPC-157 works more locally and is particularly effective for gut healing. TB-500 has better human safety data (Phase I trials), while BPC-157 has more extensive animal research. Many people combine them.

Is TB-500 banned in sports?

Yes, TB-500 is banned by WADA (World Anti-Doping Agency) and will cause a positive drug test. It's prohibited both in and out of competition. If you compete in any tested sport, professional, amateur, or collegiate, using TB-500 will result in a doping violation. This ban exists because of its healing and potential performance-enhancing properties.

How long does TB-500 stay in your system?

TB-500 can be detected in urine for approximately 5-10 days after use with current testing methods, though detection windows continue to improve. If you're subject to drug testing, assume it could be detected longer. The biological effects last longer than detectability, benefits may persist for weeks after a course.

Where do I inject TB-500?

Unlike BPC-157, TB-500 is systemic, so injection location doesn't significantly affect which tissues benefit. Subcutaneous injection in the abdominal fat or thigh is most common. You don't need to inject near an injury site. Intramuscular injection is also used but may be more uncomfortable.

What is the recommended TB-500 dosing protocol?

Common protocols use a loading phase of 2-2.5mg twice weekly for 4-6 weeks, followed by maintenance of 2mg once weekly or every two weeks. Total weekly dose during loading is typically 4-5mg. These doses come from veterinary use and biohacking communities, there's no established human medical protocol.

Can TB-500 help with hair loss?

There's anecdotal interest in TB-500 for hair growth based on its effects on cell migration and tissue repair. Some animal studies show thymosin beta-4 promotes hair growth. However, there's minimal human evidence specifically for hair loss. It's not a first-line option and would be highly experimental for this use.

Is TB-500 safe for long-term use?

Long-term safety is unknown. Phase I human trials showed TB-500 was well-tolerated for up to 14 days at high IV doses, but there are no studies on repeated subcutaneous use over months or years. Theoretical concerns include promoting blood vessel growth in unwanted areas (tumors) and unknown effects on immune function. Most protocols use it for defined periods rather than indefinitely.

Can I take TB-500 orally?

TB-500 is not effective orally, it's a peptide that would be broken down by digestive enzymes before absorption. It must be injected, typically subcutaneously. Some companies claim to sell oral thymosin beta-4 products, but these are unlikely to deliver active peptide to the bloodstream.

New to Peptides?

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What Are Peptides? Peptide Safety Guide

Related Goals

The Injury Recovery Guide

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Disclaimer: This information is for educational purposes only and is not medical advice. Many peptides discussed are not FDA-approved for human use. Always consult with a qualified healthcare provider before starting any treatment. Evidence levels and regulatory status can change, this content was last updated December 2025.

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