TB-500 Explained: Thymosin Beta-4, the Human Evidence, and What "TB-500" Actually Means
"TB-500" means different things on different labels. Here's how to tell what you're getting, and what's actually been studied in people.
Key takeaways
- Thymosin β4 is a naturally occurring 43-amino-acid protein involved in cell migration, blood-vessel formation and wound repair.
- "TB-500" can mean a short synthetic fragment of thymosin β4 (about 889 Da) or the full-length protein (about 4,963 Da).
- Thymosin β4 has been studied in people in specific forms: an IV formulation in healthy volunteers and an eye-drop formulation.
- Those studies don't validate every product sold as TB-500. Identity, route and formulation matter.
- It's prohibited at all times in tested sport, and it isn't an FDA-approved drug.
TB-500 is usually mentioned in the same breath as BPC-157, but it has a different story. The protein behind it has real human research. The name on the bottle, though, doesn't always tell you which molecule you're getting.
What thymosin β4 is
Thymosin β4 is a naturally occurring protein made of 43 amino acids. It's found in most cells and binds actin, a structural protein that helps cells move. Researchers have studied it for decades for its role in cell migration, blood-vessel formation, wound repair and inflammation [1].
What "TB-500" actually means
The name is used for two different things:
| Name used | What it is | Approx. size |
|---|---|---|
| TB-500 (anti-doping research definition) | A short synthetic fragment of thymosin β4's active region (Ac-LKKTETQ) [2] | ~889 Da |
| TB-500 (many consumer products) | Full-length thymosin β4 | ~4,963 Da |
FDA's compounding materials list "thymosin beta-4, fragment (LKKTETQ)" separately from the full-length protein [6]. If you're comparing products, ask which one you're getting, and ask for a certificate of analysis that shows identity by mass spectrometry.
What human studies exist
- IV thymosin β4 in healthy volunteers. A randomized, placebo-controlled trial tested single and multiple intravenous doses for safety and tolerability [3].
- Eye drops for a corneal condition. A Phase III trial tested a 0.1% thymosin β4 eye-drop formulation (RGN-259) in patients with neurotrophic keratopathy [4].
That's real human research, more than BPC-157 has. But it's specific: particular formulations, routes and conditions. It doesn't show that a recovery product labeled TB-500 has the same composition, reaches the same tissues or produces the same effects.
Safety
The human studies above report on specific formulations under controlled conditions. Safety data for consumer TB-500 products, especially ones sold as research chemicals, is far more limited, and contents may not match the label. Talk to a clinician before use.
FDA and anti-doping status
Thymosin β4 isn't an FDA-approved drug. The TB-500 fragment was among the peptides nominated for FDA's compounding list and later withdrawn, and in July 2026 an FDA advisory committee voted in favor of TB-500 for possible compounding eligibility; that vote is advisory and FDA hasn't acted on it [6][7].
Thymosin β4 and its derivatives, including TB-500, are prohibited at all times under section S2.3 of the 2026 WADA Prohibited List [5]. See Peptides and Drug Testing.
What TB-500 is in LavION
The TB-500 in LavION formulas is full-length thymosin β4. Its identity is confirmed by mass spectrometry on an independent certificate of analysis from MZ Biolabs, which measured a mass of about 4,960 daltons, matching the full-length protein, at 99.76% purity by HPLC.
| Formula | TB-500 per patch | Other ingredients |
|---|---|---|
| TITAN | 10 mg | BPC-157 2 mg · NAD+ 250 mg · GHK-Cu 5 mg |
| GLOW | 2 mg | GHK-Cu 15 mg · BPC-157 2 mg · NAD+ 250 mg |
These are loaded amounts, not measured delivery. Full-length thymosin β4 is a large molecule, and how much a patch delivers hasn't been measured in published human studies. LavION uses the ActivaPatch IontoGo 12.0 iontophoresis device, which applies a low electrical current to help move charged molecules across the skin during a wear period of up to 12 hours. LavION is needle-free and does not use microneedles. Ingredient amounts describe what is loaded into the formula, not measured delivery into the body.
References
- 1.Goldstein AL, Hannappel E, Sosne G, Kleinman HK. Thymosin β4: a multi-functional regenerative peptide. Basic properties and clinical applications. Expert Opinion on Biological Therapy. 2012;12(1):37-51. pubmed.ncbi.nlm.nih.gov
- 2.Ho EN, et al. Doping control analysis of TB-500, a synthetic version of an active region of thymosin β4, in equine urine and plasma by liquid chromatography-mass spectrometry. Journal of Chromatography A. 2012;1265:57-69. pubmed.ncbi.nlm.nih.gov
- 3.Ruff D, et al. A randomized, placebo-controlled, single and multiple dose study of intravenous thymosin β4 in healthy volunteers. Annals of the New York Academy of Sciences. 2010. pubmed.ncbi.nlm.nih.gov
- 4.Sosne G, et al. 0.1% RGN-259 (thymosin β4) ophthalmic solution promotes healing and improves comfort in neurotrophic keratopathy patients in a randomized, placebo-controlled, double-masked phase III clinical trial. International Journal of Molecular Sciences. 2022;24(1):554. pubmed.ncbi.nlm.nih.gov
- 5.World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026 (in force January 1, 2026). wada-ama.org
- 6.U.S. Food and Drug Administration. Certain bulk drug substances for use in compounding that may present significant safety risks (page updated April 22, 2026). fda.gov
- 7.U.S. Food and Drug Administration. July 23–24, 2026 Meeting of the Pharmacy Compounding Advisory Committee. fda.gov
Frequently asked questions
Is TB-500 the same as thymosin beta-4?
Not always. In anti-doping research, TB-500 means a short synthetic fragment of thymosin β4. Many products use the name for the full-length protein. LavION's TB-500 is full-length thymosin β4, confirmed by mass spectrometry.
Has thymosin beta-4 been studied in humans?
Yes, in specific forms: an intravenous formulation in healthy volunteers and an eye-drop formulation for a corneal condition.
Does TB-500 heal injuries?
That hasn't been shown in controlled human trials. The human research on thymosin β4 is limited to specific formulations and conditions.
Is TB-500 FDA-approved?
No. An FDA advisory committee voted in favor of TB-500 for possible compounding eligibility in July 2026, but that vote is advisory.
Is TB-500 banned in sport?
Yes. Thymosin β4 and its derivatives, including TB-500, are prohibited at all times under the WADA Prohibited List.
Which LavION formulas contain TB-500?
TITAN (10 mg per patch) and GLOW (2 mg per patch).
Keep reading
This article offers general wellness education and does not replace medical advice. Statements about LavION products have not been evaluated by the FDA, and these products are not intended to diagnose, treat, cure, or prevent disease. Peptide orders include a clinician review before fulfillment. If you are pregnant, nursing, managing a condition, or taking medication, speak with your clinician. See our medical disclaimer.