TB-500
TB-500 is sold for injury recovery and is often paired with BPC-157. It can now be compounded on prescription, but it has no completed human trials of its own. The human research people cite was done on a different, larger molecule.
- Legal lane: compounded on prescription under the October 2026 interim policy. Not FDA-approved.
- Evidence grade: D
- Form covered by the policy: TB-500 acetate as an injection under the skin or into muscle
- Established human dose: none
What it is
TB-500 is the market name for a synthetic peptide based on thymosin beta-4, a 43-amino-acid protein found in most human cells and involved in tissue repair. TB-500 is a short piece of that protein, not the whole thing.
Sources do not agree on exactly which piece. Most describe a seven-amino-acid fragment, some describe a longer one, and reviewers note that products sold under the name do not always contain the same sequence. That uncertainty is part of the risk.
What the evidence shows
For TB-500 itself, the evidence is from cells and animals. Reviews published in 2026 found no completed, peer-reviewed human trials of the fragment. One early-phase trial was registered in 2026.
The human studies often quoted in TB-500 marketing used full-length thymosin beta-4: eye drops tested for dry eye and corneal injury, and a small dose-escalation study in venous leg ulcers. Those results do not transfer automatically to a fragment given by injection for a tendon or muscle injury.
In July 2026 an FDA advisory committee considered TB-500 for wound healing and voted 8 to 6 to recommend it. FDA scientists had recommended against.
Legal status
TB-500 was restricted from compounding in 2023, removed from the restricted category in April 2026, and included in the HHS interim policy published October 30, 2026. That policy allows state-licensed pharmacies to compound it on an individual prescription. It is not approval and can be revised. TB-500 is prohibited in sport.
Reported dosing
No dose has been established in human trials. There is no human dose-response data for TB-500.
A pattern often repeated online is 2 to 2.5 mg injected under the skin twice a week for four to six weeks. The source we found for it labels it anecdotal. It does not come from a clinical study.
If a clinician prescribes TB-500, follow the dose on the prescription and ask what it is based on.
Safety
- Human safety data for the fragment is essentially absent.
- Because product identity varies, what is in a vial bought outside a pharmacy is a real unknown.
Sources
- Scoping review of thymosin beta-4 and TB-500 in tissue healing (preprint)
- Superpower: TB-500 evidence summary
- Aging wiki: TB-500 fragment, trial registry and dose-response notes
- Outliyr: TB-500 report (anecdotal protocol)
- GoodRx: FDA developments on peptides (policy forms and routes; committee votes)
- HealingMaps: committee vote margins
This compound is often sold inside a blend, such as Wolverine or KLOW. A vial holding more than one peptide falls outside the 2026 compounding policy; see blends and stacks.
See how the two repair peptides differ: BPC-157 vs TB-500.