What Is TB-500 and How Does It Work
TB-500 is a synthetic version of a fragment of Thymosin Beta-4, a naturally occurring peptide present in nearly all human cells and tissues. The full-length molecule is involved in actin regulation - it binds to G-actin, a protein central to cell structure and movement - in a way that's thought to support cell migration to sites of injury. Thymosin Beta-4 and the TB-500 fragment are also studied for a role in angiogenesis, the formation of new blood vessels, which is a biologically plausible pathway for supporting wound and tissue healing more broadly.
This is the point where it's worth being precise, because the two names get used almost interchangeably in casual conversation but refer to different things scientifically: Thymosin Beta-4 is the full-length, 43-amino-acid natural peptide, while TB-500 is a shorter synthetic fragment designed to replicate its actin-binding activity. The early-phase human clinical trial work that exists in the published literature was conducted on the full-length molecule, not on the fragment sold in the research chemical market - a distinction covered in more detail below and in TB-500 Human Studies: What Evidence Exists?.
Research Dosing
There is no completed, peer-reviewed human dose-finding trial establishing a validated dose for the TB-500 fragment. Everything in this section reflects informal research-community convention, not clinical evidence.
| Phase | Dose (commonly cited) | Frequency | Route |
|---|---|---|---|
| Loading (weeks 1-6) | 2-2.5mg per injection | Twice weekly, non-consecutive days | SubQ, typically abdomen |
| Maintenance (weeks 7-10) | 2mg per injection | Once weekly | SubQ, typically abdomen |
Context: The loading/maintenance structure above is the same convention used in community TB-500 protocols, including the TB-500 and BPC-157 stack guide. It is not derived from a completed, published human dose-finding study - treat any specific figure you see for TB-500 as informal convention, not a validated clinical dose. Neither phase requires post-cycle therapy; TB-500 does not affect the HPTA.
Regulatory Status
TB-500 is not an FDA-approved drug. It is sold as a research chemical for laboratory research use only. In July 2026, the FDA's Pharmacy Compounding Advisory Committee reviewed TB-500 alongside BPC-157, MOTS-c, and four other peptides for potential inclusion on the Section 503A Bulk Drug Substances List, and voted to recommend it. That is a nonbinding committee recommendation, not drug approval, and no final rule has been issued as of this writing. See the FDA Peptide Status Tracker and What Changed With BPC-157, TB-500 and MOTS-c in 2026? for the full regulatory picture. Consult a qualified healthcare provider before considering any peptide protocol.
What Research Shows
The preclinical research base for TB-500 is predominantly animal-based. Studies in rodents and other animal models have examined the fragment for wound healing, tissue repair, and cardiac tissue recovery following injury, and this is the primary evidence source specific to the TB-500 fragment itself. Dedicated, published human clinical trials on the fragment do not exist.
What does exist is a separate body of early-phase human clinical trial work on Thymosin Beta-4, the full-length molecule TB-500 is derived from. Those trials explored applications including chronic wound healing - such as diabetic foot ulcers and pressure ulcers - and dry eye conditions. That is real human trial data, but it was collected on a different molecule than the shorter fragment most people mean when they refer to TB-500, which is why claims about TB-500's effects in humans should currently be understood as extrapolated rather than clinically confirmed for the fragment specifically. For the full breakdown of this evidence picture, see TB-500 Human Studies: What Evidence Exists?.