PeptideSearch

TB-500

Animal studies only

Get notified when the evidence changes.

Almost all the research is in animals. We do not know if the same thing happens in people.

Compiled and reviewed by the PeptideSearch Editorial Team · Status checked 2026-06-30

Also called Thymosin Beta-4 fragment / TB4 frag 17-23

A fragment of a natural protein studied for wound repair and cell movement, mostly in animals. There is no approved human use.

TB-500 is a seven-amino-acid fragment of thymosin beta-4, the full 43-amino-acid protein. They are not the same compound, and almost all of the research is on the protein: see what the research shows on Thymosin Beta-4.

The basics

What is it?
A short piece of a natural body protein called thymosin beta-4, which helps cells move around.
What do we know?
In animals, it seems to help cells move into damaged areas, which is part of how wounds close.
What do we still not know?
Whether any of that happens in people. Human studies are missing.

Watch: what the research shows

TB-500: What The Research Actually Shows

We counted every paper on TB-500. Seven of them. Two animal studies, four reviews, zero done in people.

Official status: 503A Category 2 – significant safety risk · Checked 2026-06-30

Can a doctor prescribe this?

Small pharmacy (503A)
An FDA panel said yes — nothing has changed yet
Large outsourcing facility (503B)
Never put forward to FDA

Not FDA approved and placed in the restricted category for 503A compounding.

503A is a pharmacy making a single prescription for one patient. 503B is a facility making batches. They are governed by separate lists. Where a category is shown, it is a position on the FDA's list of substances that have been put forward and are still being worked through — not the final list, which is set by rulemaking. Category 1 means the FDA does not plan to act against a pharmacy that makes it while the review runs.

What FDA actually looked at

FDA reviewed this peptide for Wound healing. That is a narrower question than the uses this peptide is usually marketed for.

What happens next

FDA has not said whether it will move TB-500 into Category 1 while it decides, and has not started formal rulemaking.

Without a Category 1 placement, nothing changes for pharmacies no matter how the vote went.

The July 2026 vote covered the 503A list only. No 503B review has been scheduled.

503B is the pathway that would allow large-scale supply. It has not moved.

Lab suppliers we list: 16

Doses used in research

Taken word for word from the studies and trials listed on this page. This is not a recommendation and not a dose for anyone to take.

Spot an error? corrections@peptidesearch.org

What has happened so far

  1. 23 July 2026503A

    FDA proposed that TB-500 NOT be included on the 503A Bulks List. FDA reported no direct human administration studies.

    FDA briefing documentnot yet verified against primary source

  2. 23 July 2026503A

    The committee voted 8-6 with one abstention to recommend TB-500 for the 503A Bulks List, against FDA staff's recommendation. Advisory only.

    8–6, 1 abstained

    Press reportnot yet verified against primary source

  3. 16 April 2026503A

    FDA published a Federal Register notice announcing a Pharmacy Compounding Advisory Committee meeting for July 23-24, 2026 at the White Oak campus, to consider seven peptides for the 503A Bulks List.

    Federal Registernot yet verified against primary source

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