Head to head
TB-500 against Thymosin Beta-4
The parent peptide and the fragment sold under a research name. This is the single most consequential mix-up in the healing peptide market, because the clinical trial record belongs to only one of them.
Column A
TB-500TB-500 (N-acetylated thymosin beta-4 fragment 17 to 23, Ac-LKKTETQ)
A seven-residue fragment of thymosin beta-4 sold under a research name. No published study has given TB-500 to people; the clinical trial record usually quoted for it belongs to the full 43-residue parent peptide, which is a different molecule.
Column B
Thymosin Beta-4Thymosin Beta-4 (TB4)
A naturally occurring actin-binding peptide studied for wound healing, cardiac repair, and eye conditions; the parent molecule of TB-500.
The mistake this page exists to correct
TB-500 is sold on the strength of the thymosin beta-4 clinical programme. That programme tested the full 43 residue peptide. What is in the vial is a seven residue acetylated fragment, Ac-LKKTETQ. A mass spectrometry analysis from Ghent University in 2012 and the FDA evaluation of 2026 both identify the marketed substance as the fragment. No published study has given TB-500 to people. Check the mass on a certificate of analysis before assuming which molecule you have.
Side by side, on the facts we can check
| Attribute | TB-500 | Thymosin Beta-4 |
|---|---|---|
| Category | Healing & Recovery | Healing & Recovery |
| FDA status | Not FDA-approved. Removed from Category 2 (April 2026); PCAC voted 8 to 6, one abstention, to recommend for compounding (July 2026) against the FDA reviewers' recommendation; awaiting FDA action | Not FDA-approved; investigational (clinical trials for eye conditions) |
| Half-life | Not established in humans | ~2 hours |
| Molecular weight | 889.0 Da (free base); 949.1 Da (acetate) | 4,963.4 Da |
| Mechanism | The LKKTET sequence inside the fragment is the actin-binding region of thymosin beta-4. The hypothesis is that it binds monomeric G-actin the way the parent peptide does, supporting actin filament turnover, cell migration and angiogenesis at an injury site. FDA's review notes that the wound-healing work was done mostly with the non-acetylated heptapeptide or with the full parent peptide, and that those results cannot be extrapolated directly to the acetylated fragment sold as TB-500. | Binds actin to regulate the cytoskeleton, promoting cell migration, angiogenesis, and reduced inflammation at injury sites. |
| Human studies cited | 2 | 2 |
| Legal status, US | Not approved; research use only | Not approved; research use only |
Frequently asked questions
What is the difference between TB-500 and Thymosin Beta-4?
TB-500: A seven-residue fragment of thymosin beta-4 sold under a research name. No published study has given TB-500 to people; the clinical trial record usually quoted for it belongs to the full 43-residue parent peptide, which is a different molecule. Thymosin Beta-4: A naturally occurring actin-binding peptide studied for wound healing, cardiac repair, and eye conditions; the parent molecule of TB-500.
Which has stronger research evidence, TB-500 or Thymosin Beta-4?
This database does not grade compounds. It counts what was run in people: 2 of the 9 studies cited on the TB-500 profile were human work, against 2 of 4 for Thymosin Beta-4. Those counts are of our own citation lists and understate any larger literature, and neither is a recommendation.
Are TB-500 and Thymosin Beta-4 FDA-approved?
TB-500: Not FDA-approved. Removed from Category 2 (April 2026); PCAC voted 8 to 6, one abstention, to recommend for compounding (July 2026) against the FDA reviewers' recommendation; awaiting FDA action. Thymosin Beta-4: Not FDA-approved; investigational (clinical trials for eye conditions).
Related posts
Blog articles that cover TB-500 or Thymosin Beta-4, newest first.
- Healing & Recovery / Sep 8, 2026 / 9 minPeptides for Joint Pain: BPC-157, TB-500, Lorecivivint, Pentosan and Collagen Peptides, Evidence Tiered
- Safety / Sep 8, 2026 / 9 minPeptide Side Effects by Class: What Is Documented, What Is Anecdotal
- Safety / Sep 8, 2026 / 8 minHow to Read a Peptide Certificate of Analysis: HPLC Purity, Mass Spec Identity, Endotoxin, and Janoshik Verification
- Healing & Recovery / Sep 8, 2026 / 8 minGLOW vs KLOW vs Wolverine: What Is in Each Stack and What the Evidence Says, Ingredient by Ingredient
Reviewed Sep 2026. This page sets two published records side by side. It is educational, it is not medical advice, and it contains no dosing protocols or recommendations for personal use.