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Is TB-500 safe?

Unapproved
TB-500 is a lab-made fragment of thymosin beta-4 with no approved use. The FDA says it has not identified any human exposure data for it, and advisers narrowly backed its compounding in 2026 against FDA staff advice.
Not approved for human use by the FDA or Health Canada. The human evidence is limited, animal-only, or absent. Material sold outside regulated channels also has no verified identity, purity or stability, which is a separate risk from the molecule itself.

Updated October 2026 · Checked against FDA, ABC News (secondary), AJMC (secondary), World Anti-Doping Agency

Name
TB-500
Also known as
Thymosin beta-4 fragment, Ac-LKKTETQ
Class
Synthetic peptide fragment of thymosin beta-4
Verdict
Unapproved Not approved; evidence thin or absent
Human evidence
Animal-only
Updated
October 2026

What is TB-500?

Thymosin beta-4 is a protein found throughout the body that is involved in cell movement and tissue repair. TB-500 is a short synthetic fragment, often described as the actin-binding region of that protein. It is marketed to athletes for injury recovery, but it is a different substance from full-length thymosin beta-4, so results with one cannot be assumed for the other. It is not an approved medicine in the US or Canada.

What it is claimed to do

These are the uses TB-500 is promoted for. Listing a claim is not endorsing it — the next section is where each one meets the evidence.

What the human evidence shows

Evidence: Animal-onlyStudied in animals or in cell culture, with no completed trial in humans. Animal results routinely fail to reproduce in people, so this level supports no human conclusion at all.

The evidence for TB-500 itself is thin. The FDA states that it has not identified any human exposure data for this fragment and lacks important information about its safety. Studies on full-length thymosin beta-4 in the eye, skin and heart exist, but they used a different molecule, and they do not show that TB-500 sold online works for injuries. At the FDA advisory committee in July 2026, an FDA scientist questioned what form patients would actually receive, noting that the identity of the product matters before it can be placed on any list.

Known risks and side effects

Regulatory status as of October 2026. Approval, prescription status and compounding restrictions change without notice, and the two countries move independently. Check the regulator directly before relying on any of it.

United States

Approved for human use
No — not approved by the FDA for any human use
Prescription only
Not applicable or not yet determined

Not FDA approved. On July 23, 2026 the FDA's Pharmacy Compounding Advisory Committee voted 8 to 6 to recommend adding TB-500 to the bulk substances list for compounding, against the unanimous advice of FDA staff; the vote is non-binding. HHS's October 29, 2026 draft enforcement-discretion policy covers TB-500 acetate (subcutaneous or intramuscular) for state-licensed pharmacies and physicians under conditions. HHS says this is a draft, is not an approval, and does not mean the products were reviewed for safety, effectiveness or quality. A prescription would still be required.

Canada

Approved for human use
No — not approved by Health Canada for any human use
Prescription only
Not applicable or not yet determined

We found no Health Canada authorization for TB-500 as a drug. Products sold online as research chemicals are not authorized for human use.

Who should avoid TB-500

Frequently asked questions

Is TB-500 safe?

Its safety in people has not been established. The FDA has not identified any human exposure data and notes immune-reaction and impurity concerns.

Is TB-500 the same as thymosin beta-4?

No. TB-500 is a short synthetic fragment, while thymosin beta-4 is a full-length protein. Research on one does not automatically apply to the other.

Is TB-500 legal?

It is not an approved drug in the US or, as far as we found, Canada. US compounding is moving toward limited allowance with a prescription through an advisory vote and a draft HHS policy, but neither is an approval.

Sources

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Educational information only. This page summarises published evidence and regulatory records about TB-500. It is not medical advice, it is not a recommendation for or against use, and it cannot account for your history, medications or conditions — that is a conversation for a licensed clinician.We sell nothing, name no seller, and carry no affiliate or vendor links. See the full disclaimer and ourmethodology.