What Is Thymosin Beta-4 (full)?
Thymosin β4 is a naturally occurring 43-amino-acid regulatory peptide whose main cellular role is binding and sequestering actin, and which is involved in cell migration, angiogenesis, and tissue repair. The full-length molecule (as a synthetic drug candidate, developed under names such as RGN-259 for the eye) has been studied for wound healing, dry eye disease, and cardiac repair. Unlike the TB-500 fragment sold to consumers, full-length thymosin β4 has genuinely reached human clinical trials — though it remains an investigational agent, not an approved dietary supplement, and efficacy across most indications is still unproven.
Evidence
Human evidence is strongest in ophthalmology. A small multicentre, randomised, double-masked, placebo-controlled Phase 2 trial of thymosin β4 eye drops (RGN-259) in patients with severe dry eye reported statistically significant improvements in ocular discomfort and corneal staining versus vehicle control, and the drops were well tolerated 1Reference 1RCTThymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial — randomised controlled trial (Phase 2)View study →. Beyond the eye, much of the wound-healing and cardiac-repair evidence remains preclinical (animal) or early-phase, and broad claims that thymosin β4 heals injuries or reverses tissue damage in humans generally are not established by verified late-stage trials in this pass. The molecule holds orphan-drug designations for some ocular indications but has not received full approval.
Dosage & Safety
Because thymosin β4 is an investigational drug rather than an approved supplement, there is no established over-the-counter dose; the human data comes from controlled trials of specific pharmaceutical formulations (e.g. 0.1% ophthalmic solution) 1Reference 1RCTThymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial — randomised controlled trial (Phase 2)View study →, and this page makes no dosing recommendation. Early-phase trials of the full molecule reported acceptable tolerability, but long-term safety, systemic use, drug interactions, and pregnancy/lactation safety are not established, and it is prohibited in sport. This entry is informational only and is not an endorsement of use.
References
- Sosne G, Dunn SP, Kim C (2015). Thymosin β4 significantly improves signs and symptoms of severe dry eye in a phase 2 randomized trial — randomised controlled trial (Phase 2). Cornea. https://pubmed.ncbi.nlm.nih.gov/25826322/