TB-500 / Thymosin Beta-4

About TB-500 / Thymosin Beta-4

TB-500 is a synthetic fragment of thymosin beta-4, a protein produced at higher concentrations at injury sites. In animal studies it promotes cell migration, blood-vessel growth, and wound healing. The evidence for TB-500's marketed recovery uses is preclinical (animal) — TB-500 itself has not been tested in human trials. Its parent protein thymosin beta-4 has been studied in humans, but as an eye drop (RGN-259) for dry eye and corneal healing — a different formulation, route, and indication. Be aware that vendors use "TB-500" and "Thymosin Beta-4" interchangeably for the same product, so the label tells you very little about what is in the vial. A vetted vendor's listing checked in August 2026 was titled "Thymosin Beta-4," described itself as an "analog," and published a molecular formula matching the full-length 43-amino-acid protein rather than a short fragment. Two things follow: check the molecular formula or mass-spec identity rather than the product name if the distinction matters to you, and do not assume the RGN-259 eye-drop trial results apply to an injected vial regardless of which name is on it.

Key Benefits

• Promoted cell migration and wound healing in animal studies
• Supported blood-vessel growth (preclinical)
• Reduced inflammation and improved recovery in animal models
• TB-500 itself not tested in human trials

Category Ratings

How to Take

Common Side Effects

• Headache
• Nausea
• Injection site redness
• Temporary lethargy

Legal & Regulatory Status

Research use only; not FDA-approved. Thymosin beta-4, its parent molecule, has been studied through Phase 2–3 as an ophthalmic solution (RGN-259) for dry eye and neurotrophic keratopathy; neither TB-500 nor any injected form has been through human trials.

Safety and regulatory details for FDA-approved compounds are drawn from the official product label via openFDA; clinical development status reflects ClinicalTrials.gov. This information is provided for research reference, is not endorsed by the FDA, and may not be complete or current.

Research & Sources

• Thymosin β4 (RGN-259) improves dry eye — phase 2 RCT (PMID 25826322)
• RGN-259 in neurotrophic keratopathy — Phase 3 RCT; parent protein, ophthalmic route (PMC9820614)
• Thymosin β4 ophthalmic solution for dry eye — Phase 2 RCT, CAE model (PMID 26056426)

Sources are selected for reliability (peer-reviewed literature, openFDA, ClinicalTrials.gov) but this is a research summary, not medical advice, and may not be exhaustive.