Thymosin Beta-4 (TB-500)
Thymosin Beta-4 (TB4) is a highly conserved 43-amino acid peptide that regulates actin polymerization through G-actin sequestration, promoting cell migration, angiogenesis, tissue repair, and anti-inflammatory signaling across multiple organ systems. Human clinical programs have evaluated TB4 in dry eye disease, neurotrophic keratopathy, and chronic wound indications, with modest positive signals in some endpoints but no approved indication to date. 'TB-500' is a commercial label commonly applied to either the full TB4 peptide or its actin-binding fragment (residues 17–23) — the two are pharmacologically distinct, and product labeling in the research market is frequently inconsistent. Buyers should be aware that what is sold as TB-500 may be the fragment, full TB4, or a mixture, making direct comparisons to specific published studies unreliable.
Evidence last reviewed: 13 May 2026
Not a routine supplement — not recommended for self-directed use.
Information here is educational only, not a recommendation to use. See our Safety page.
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Evidence is from research or clinical settings — does not imply safety outside supervised contexts.
The evidence for TB4 primarily comes from early clinical trials and preclinical studies, showing modest effects on wound healing. However, the lack of approved indications and variability in product formulations limit its reliability and applicability.
Wound healingRat full-thickness wound model · Preclinical animal studyLow
TB4 accelerated wound healing endpoints in a rat model compared with controls.
Wound healing (reviewed clinical context)Stasis and pressure ulcer clinical programs · Review articleLow
A review summarizes phase 2 wound-healing programs reporting faster healing in those that did heal; note that these are not sports injury RCTs.
Wound healing (clinical development)Patients with venous stasis ulcers · Registered phase 2 trial (TB4 gel)Low
TB4 gel has been studied in venous stasis ulcer indications; registry evidence supports clinical testing, though effect sizes depend on the specific trial & endpoint reporting.
KLOW Stack
The KLOW stack is a 4-peptide protocol targeting systemic inflammation, tissue repair, and cellular regeneration. It combines BPC-157 (gut and musculoskeletal healing), TB-500 (vascularisation and muscle/tendon recovery), KPV (anti-inflammatory gut protection), and GHK-Cu (collagen remodelling and skin/hair health). It is designed as an evolution of the GLOW stack with a stronger anti-inflammatory focus and broader systemic repair coverage.