Key takeaways

  • TB-500 is a short synthetic peptide based on part of thymosin beta-4, a protein the body makes.
  • Thymosin beta-4 has been studied in animals and small human trials, with mixed results.
  • TB-500 itself has not been tested in published human trials and is not approved.

Thymosin beta-4 is a protein found in most cells in the body. It helps cells move around and build new blood vessels, both of which matter when tissue is repairing itself.

TB-500 is a lab-made peptide built around the short section of thymosin beta-4 that researchers believe drives much of this activity. It is much smaller than the full protein.

What does the research show?

Studies in animals and cells have linked thymosin beta-4 to faster wound healing and to repair in the heart and the eye. A few small human trials tested the full protein, mostly as eye drops or a gel on the skin. Results were mixed.

Here is the problem. Almost all of that research used thymosin beta-4, not TB-500. A fragment of a protein does not necessarily behave like the whole thing. There are no published human trials of TB-500.

TB-500 is not approved for any medical use. Like BPC-157, it was restricted from pharmacy compounding by the FDA in 2023 and taken off that list in April 2026 after nominations were withdrawn. It remains unapproved. It is banned in sport.

What are the risks?

  • Its safety in people has never been formally studied.
  • Because it may promote blood vessel growth, some researchers have raised concerns about people with existing tumors.
  • Unregulated products may not contain what the label says.

The bottom line

TB-500 borrows its reputation from research on a different molecule. Whether it does anything useful or harmful in people is an open question.

References

  1. Goldstein AL, Hannappel E, Sosne G, Kleinman HK. Thymosin beta4: a multi-functional regenerative peptide. Expert Opin Biol Ther. 2012;12:37-51.
  2. U.S. Food and Drug Administration. Safety risks associated with certain bulk drug substances nominated for use in compounding (2023) and status update (April 2026).
  3. World Anti-Doping Agency. The Prohibited List.