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Saunatica

Peptide

TB-500

  • Peptide
  • Tissue & recovery research
  • Not FDA-approved

TB-500 is a lab-made seven-amino-acid fragment of thymosin beta-4 that has drawn interest for wound and tissue repair. Direct evidence for TB-500 itself is extremely limited, and it has never been studied as an administered treatment in people.

The basics

What is it?

TB-500 is a synthetic, N-acetylated peptide containing seven amino acids. Its sequence comes from positions 17 through 23 of thymosin beta-4, a much larger 43-amino-acid protein. TB-500 is not full-length thymosin beta-4, so findings about the full protein cannot automatically be applied to TB-500. The fragment includes an actin-binding region that researchers think could affect cell movement, but whether this explains any wound-healing effect remains unknown.

Why it comes up

What are people interested in it for?

  • Wound-repair research
  • Tissue recovery
  • Muscle and tendon recovery
  • Inflammation research
  • Cell movement and actin signaling

Most claims in these areas come from studies of full-length thymosin beta-4, a chemically different unacetylated fragment, or online marketing. They are not supported by human trials of TB-500 itself.

Evidence

What does the research show?

Animal evidence

FDA found no in-vivo study showing that actual acetylated TB-500 free base or acetate promotes wound healing. An older study in aged mice reported changes in skin closure and collagen, but it used unacetylated LKKTETQ, which is chemically different from TB-500. In a 2024 laboratory study, parent TB-500 did not improve closure in a fibroblast scratch model; one smaller metabolite showed a modest effect in the dish. Rat and horse studies have examined how TB-500 is absorbed and broken down, not whether it improves disease or healing.

Human evidence

There are zero published human administration studies, zero human randomized controlled trials, and no published human cohorts, case series, case reports, or pharmacokinetic studies. Studies of full-length thymosin beta-4 do not count as TB-500 evidence. A 2026 ClinicalTrials.gov-style record that appears to describe a TB-500 trial identifies itself as fictional and is not human evidence.

Evidence grade

No formal GRADE assessment was found. Direct human evidence is absent, and even the direct animal efficacy evidence for acetylated TB-500 is missing. Describing the evidence as very low certainty is an editorial assessment, not a published letter grade.

Unknowns and risks

What about safety?

FDA found no TB-500 studies covering acute toxicity, repeated exposure, genetic damage, reproductive or developmental effects, or cancer risk. A FAERS search through March 26, 2025 found no reports, while two reports mentioning blended TB-500 and BPC-157 contained no safety assessments. Sparse voluntary reporting does not establish safety. Human risks, long-term effects, immune reactions, product identity, impurities, and peptide aggregation remain unknown.

Regulatory status

Is it legal / FDA-approved?

  1. 1TB-500 free base and acetate are not FDA-approved, have no applicable USP/NF drug-substance monograph, and are not components of an FDA-approved drug.
  2. 2TB-500 was previously associated with a 503A Category 2 nomination, but that nomination was withdrawn. It is now listed by FDA under substances nominated but withdrawn — not as a current Category 2 or Category 1 substance.
  3. 3TB-500 is not on the final 503A Bulks List. Withdrawal from Category 2 did not authorize compounding or create Category 1 enforcement discretion.
  4. 4On July 23, 2026, PCAC reviews TB-500 for wound healing. FDA staff currently proposes not adding either the free base or acetate form. The committee's recommendation is nonbinding, and FDA has not issued a final decision.
  5. 5Products sold online may be labeled "research use only." That label is not FDA approval or authorization for human administration.
  6. 6WADA prohibits thymosin beta-4 and derivatives such as TB-500 in sport. That anti-doping rule is separate from FDA drug and compounding status.

A practical checklist

Questions to ask a licensed provider

  • Is the evidence being discussed actually about TB-500, or about full-length thymosin beta-4?
  • Are there any published human studies for the reason I'm considering this?
  • What is known — and not known — about short- and long-term safety?
  • What is its current FDA and compounding status?
  • How would the product's identity, purity, sterility, and peptide impurities be checked?
  • Are there approved options with stronger human evidence?
  • What side effects or warning signs should we discuss?