TB-500: what it is and what the evidence says
A synthetic seven-amino-acid fragment of thymosin beta-4, the region that binds actin; it is studied for its role in cell migration and in the general repair of soft tissue.
Last reviewed: August 16, 2026 · How we verify this
The ground it plays on
Tissue repair happens in phases, not all at once: an initial inflammation that is actually useful, the building of new tissue, and then its remodeling, which can take months. Compounds studied in this area relate to one of those phases. None of them replaces rest or rehabilitation, and that is precisely the most common mistake people make when reading about them.
What it is studied for
Systemic recovery, mobility after an injury, soft tissue repair.
There is a distinction that almost always gets lost. A compound being studied for something is not the same as achieving it. And even where it works in a dish or in a mouse, that says little about whether it works in a person or whether the benefit is worth the risk. The section below therefore carries more weight than everything above it.
What the human evidence says
The trials in people were done with full-length thymosin beta-4: intravenous safety in healthy volunteers (2010 and 2021), phase 2 in dry eye (2015), a randomized study in venous ulcers (2007), and phase 3 in neurotrophic keratopathy (2023). The TB-500 fragment still has no clinical trials of its own.
The limitation that matters most
TB-500 is the acetylated 17-23 fragment of the protein, and data from the full molecule do not carry over to it automatically. Trials in people with the fragment, its pharmacokinetics, and studies in tendon, muscle, or joint are still missing; a 2024 study suggests that part of its activity could be due to a metabolite.
Regulatory status
Not approved by any agency. In the United States, the FDA removed it from Category 2 in April 2026 and its advisory committee voted in July 2026 in favor of allowing pharmacies to compound it, a recommendation that still needs a rule to take effect. Full-length thymosin beta-4 remains in ophthalmic clinical trials. Prohibited at all times in sport by WADA (section S2).
Status can change and varies by country. Always verify the rules in force where you live before drawing conclusions.
Cautions and context
It acts throughout the body and still has no clinical trials of its own in people; the existing ones were done with full-length thymosin beta-4. A history of cancer is reviewed with your doctor, and the certificate of analysis should confirm which molecule the vial contains.
With a diagnosed injury, ongoing medication, or new symptoms, have a professional assess it before you use it or combine it with another recovery strategy.
What this page cannot give you
A reference page can take you this far. You know what TB-500 is and where its research stands, which already puts you ahead of most readers. Four questions remain that no encyclopedia can answer for you, because the answers depend on your own situation:
- What would you measure beforehand, so that later you could tell whether anything actually changed?
- What would you watch along the way, and how consistently?
- What would you ask a professional, and in how much detail, so you do not walk out with a textbook answer?
- What would make you stop?
That is what the course is for
PeptiXtreme is ${CIF.LECCIONES} lessons that hand out no numbers. Each one ends with your starting point, what to watch along the way, the specific questions you take to a professional and the signals that mean stop. It includes per-module exams, a Certificate of Completion with a verifiable certificate ID, a Progress Tracker to follow how you are doing, and a human advisor you can actually write to.
See the course → Or measure your judgment, freeReferences
Every entry links to its record on PubMed, the US National Library of Medicine database. Open them and check. We would rather have a reader who verifies than one who takes our word for it.
- A first-in-human, randomized, double-blind, single- and multiple-dose, phase I study of recombinant human thymosin β4 in healthy Chinese volunteershuman J Cell Mol Med · 2021 · PMID 34346165 →
- Thymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trialhuman Cornea · 2015 · PMID 25826322 →
- Thymosin beta 4 ophthalmic solution for dry eye: a randomized, placebo-controlled, Phase II clinical trial conducted using the controlled adverse environment (CAE) modelhuman Clin Ophthalmol · 2015 · PMID 26056426 →
- A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin beta4 in healthy volunteershuman Ann N Y Acad Sci · 2010 · PMID 20536472 →
- Thymosin beta-4 and venous ulcers: clinical remarks on a European prospective, randomized study on safety, tolerability, and enhancement on healinghuman Ann N Y Acad Sci · 2007 · PMID 17495250 →
- Thymosin β4: a multi-functional regenerative peptide. Basic properties and clinical applicationsreview Expert Opin Biol Ther · 2012 · PMID 22074294 →
- Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500, a product suspected to possess doping potentialpreclinical Drug Test Anal · 2012 · PMID 22962027 →
- The potential use and abuse of thymosin β-4 in sport and exercise sciencereview J Sports Sci · 2013 · PMID 23421910 →
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Frequently asked questions
What is TB-500?
A synthetic seven-amino-acid fragment of thymosin beta-4, the region that binds actin; it is studied for its role in cell migration and in the general repair of soft tissue. It is studied within the area of regenerative.
Is there human evidence for TB-500?
The trials in people were done with full-length thymosin beta-4: intravenous safety in healthy volunteers (2010 and 2021), phase 2 in dry eye (2015), a randomized study in venous ulcers (2007), and phase 3 in neurotrophic keratopathy (2023). The TB-500 fragment still has no clinical trials of its own.
Is it approved by any health agency?
Not approved by any agency. In the United States, the FDA removed it from Category 2 in April 2026 and its advisory committee voted in July 2026 in favor of allowing pharmacies to compound it, a recommendation that still needs a rule to take effect. Full-length thymosin beta-4 remains in ophthalmic clinical trials. Prohibited at all times in sport by WADA (section S2).
What is the dose of TB-500?
We do not publish dosages. This is not an oversight. No single figure works for everyone: the regimen depends on a person's medical history, on whatever medication they already take, and on the goal they are chasing, which is something a professional weighs with the case in front of them. What you can build is the ability to walk into that appointment knowing what to ask.
Where can I learn to evaluate this properly?
This page tells you what TB-500 is and what the evidence says. The PeptiXtreme course teaches the other half: what you would measure before considering anything, what you would watch, the specific questions you would take to a professional and when you would stop.