TB-500 vs thymosin beta-4: are they the same?
| Question | Thymosin beta-4 | TB-500 |
|---|---|---|
| What it is | Full-length endogenous actin-sequestering peptide | Non-standardized name generally used for a synthetic fragment or derivative |
| Human evidence | Limited early-phase research for recombinant full-length thymosin beta-4; no established injectable efficacy indication | No completed human efficacy trial establishing the marketed injury-recovery claims |
| FDA status | Not FDA approved | Not FDA approved |
| PeptideGrids grade | Grade D: Preclinical or anecdotal only | Not separately graded because products sold under this name are not a single standardized clinical entity |
The chemical distinction matters
Results from studies of full-length recombinant thymosin beta-4 cannot automatically be assigned to a shorter fragment sold as TB-500. Sequence length, purity, formulation, route, and exposure can change biological activity and safety. Product labels using “TB-500” do not establish that the tested material matches a published clinical intervention.
What the evidence actually supports
Evidence is limited primarily to animal and preclinical studies; the evidence base for systemic injectable use in humans is early and incomplete. Thymosin Beta-4 (TB-4) is an endogenous actin-sequestering peptide with roles in cell migration, wound repair, and inflammation modulation, studied in animal models for cardiac, ocular, and tissue healing indications. A Phase I study in healthy volunteers established preliminary safety and pharmacokinetic data for recombinant human TB-4 given intravenously, and early-phase cardiovascular trials have been conducted, but no efficacy RCT has met its primary endpoint or supported regulatory approval in any indication. TB-500, a synthetic fragment of TB-4 used in the wellness market, has even less human evidence than the full-length recombinant protein.
The injury-healing narrative relies mainly on cell and animal models. Those experiments can justify further research, but they do not establish that an unapproved injectable product improves recovery in people.
Safety and regulatory status
Systemic injectable TB-4 has limited human safety data beyond early-phase studies. The Phase I data described mild and tolerable adverse events in healthy volunteers, but these studies were not designed to detect longer-term or population-specific harms. No human efficacy evidence exists for the indications most commonly marketed (tissue repair, recovery, anti-aging). Animal data include concerns about potential pro-fibrotic effects of TB-4 in hepatic stellate cells under certain conditions. The compound was placed on the FDA Category 2 restricted list before being removed in April 2026; like BPC-157, it is pending formal PCAC advisory review in July 2026. Compounded TB-500 formulations are not equivalent to the recombinant protein studied in clinical trials and have no specific safety data.
The FDA bulk-substance record identifies “Thymosin beta-4, fragment (LKKTETQ), also known as TB-500” in its compounding materials. PeptideGrids does not sell, source, or provide dosing guidance for either substance.
Related evidence reviews
Read the full thymosin beta-4 evidence review, compare thymosin alpha-1 vs beta-4, or review the evidence behind the Wolverine Stack.