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Limited EvidencePeptide

TB-500

Thymosin beta-4 fragment 17–23

Experimental peptide fragment

Last updated: October 2026
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TB-500 is a short fragment of thymosin beta-4, not the full-length molecule. Human studies cited in marketing often tested full-length thymosin beta-4 by a different route for a different condition. In its July 2026 review, FDA staff reported that it did not identify clinical studies or reliable human exposure data for TB-500 itself. Human injury recovery from the fragment remains unproven.

Evidence Level: Limited Evidence

Limited or indirect human evidence; confidence varies by outcome

Regulatory Status: No FDA-approved TB-500 drug. FDA staff reviewed the TB-500 fragment for compounding in July 2026; the review is not a final rule.

How It Works

Thymosin beta-4 is a larger peptide involved in cellular processes. TB-500 represents amino acids 17–23 of that molecule. Shared sequence does not establish shared clinical effects or safety. A claim about injected TB-500 requires studies of that exact fragment, route and outcome; full-length eye-drop or wound-gel trials cannot substitute.

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

TB-500 accelerates recovery from human muscle, tendon or ligament injury.

Population: Injured people; no clinical studies of the fragment were identified in FDA’s 2026 review.

Why this rating

Clinical work on full-length thymosin beta-4 is indirect and cannot establish an injury benefit for the TB-500 fragment.

Supporting studies

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

Full-length thymosin beta-4 eye drops may improve dry-eye measures.

Population: Adults with dry eye treated with topical full-length thymosin beta-4, not TB-500.

Why this rating

A small phase 2 trial measured dry-eye outcomes. It is not a TB-500 trial and does not establish fragment efficacy.

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 October 2026· Designing Longevity EditorialHow we grade

Potential Benefits

  • The relationship to thymosin beta-4 provides a laboratory research question
  • Full-length thymosin beta-4 has been studied separately in human dry-eye trials, but those results do not establish TB-500 benefit

Risks & Considerations

  • No identified clinical efficacy studies or reliable human exposure data for TB-500 itself in FDA’s 2026 review
  • Safety of the marketed fragment and common routes is not established by full-length thymosin beta-4 studies
  • The molecule, route and claimed recovery outcome may differ from the study a seller cites
  • Product identity and purity cannot be inferred from a research-use label

Dosing Information

There is no FDA-approved TB-500 recovery indication or established human dosing protocol. Doses reported for another molecule or from online protocols are not validated for this fragment.

Need to mix this from a vial?

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

Practical Tips

  • 1Confirm whether a cited paper tested the 17–23 TB-500 fragment or full-length thymosin beta-4
  • 2Check whether the studied outcome was an injury, dry eye, a wound or only a laboratory measurement
  • 3Discuss an injury and established recovery care with a licensed clinician

Key Research

FDA July 2026 review of TB-500

U.S. Food and Drug Administration, 2026

FDA staff identified TB-500 as a fragment and did not identify clinical studies or reliable human exposure data for the fragment.

View Study

FDA TB-500 substance identity

U.S. Food and Drug Administration

TB-500 is identified as a thymosin beta-4 fragment, not full-length thymosin beta-4.

View Study

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

Clinical Ophthalmology, 2015

This trial tested topical full-length thymosin beta-4 for dry eye, not TB-500 or injury recovery.

View Study

Read the recovery evidence

TB-500 is a fragment of thymosin beta-4; full-length findings do not establish fragment benefits.

Compare TB-500 and BPC-157Peptide safetyResearch evidence

For medical decisions, discuss established options with a licensed clinician.Human outcome evidence here is limited.

Frequently Asked Questions

Are TB-500 and thymosin beta-4 the same?

No. TB-500 is a short fragment of the larger thymosin beta-4 molecule. A study of the full-length molecule does not directly test the fragment.

Does a human thymosin beta-4 trial prove TB-500 works?

No. Human dry-eye studies used full-length thymosin beta-4 by a different route and for a different condition.

Has TB-500 been shown to heal injuries in people?

FDA staff reported that their 2026 review did not identify clinical studies or reliable human exposure data for TB-500 itself.

Is TB-500 FDA approved?

No FDA-approved TB-500 drug exists. FDA’s 2026 compounding review was not an approval.

What dose or injection location is recommended?

There is no approved injury-recovery indication or validated human dosing or injection protocol for TB-500.

New to Peptides?

Learn the basics of peptide therapy, how to inject safely, and what to look for in quality sources.

What Are Peptides? Peptide Safety Guide

Related Goals

The Injury Recovery Guide

Compare TB-500

BPC-157 vs TB-500

What was actually studied for injury recovery?

Related Peptides

BPC-157Experimental peptide
GHK-CuCopper-Binding Peptide
Thymosin Alpha-1Immune-Modulating Peptide

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 October 2026.

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