As of September 2026, the FDA and the EMA have not approved any product sold as TB-500. The name is a seller's label for thymosin beta-4 or a piece of it, with no agreed chemical identity behind it. No human trial has tested a product sold under this name. WADA bans it in sport at all times. So the label alone cannot tell you what a given vial holds.
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What is TB-500?
TB-500 is a seller's name, used loosely for lab-made thymosin beta-4 or for a smaller piece of it. Thymosin beta-4 is a natural protein involved in cell movement and tissue repair, and it has been studied since the 1990s for wound healing. No agreed chemical identity stands behind the TB-500 label, and products sold under it are unregulated.
Does TB-500 work?
Nobody knows. No human trial has tested a product sold as TB-500, and the registered human trials used full-length, pharmaceutical-grade thymosin beta-4.
What we found. 0 completed randomized trials. 2 completed human trials of pharmaceutical-grade thymosin beta-4, and 1 animal study. The randomized Phase 2 dry-eye trial on the list does not count, because it tested a different, pharmaceutical-grade product.
| Study | Tested in | Status | What it shows |
|---|---|---|---|
| Phase 2 trial of RGN-137, thymosin beta-4 made for skin wounds | People | Completed. Company-sponsored | Company trials explored the healing of skin wounds. The product is not approved by the FDA |
| Phase 2 trial of a thymosin beta-4 eye solution for dry eye, NCT01387347 on ClinicalTrials.gov (opens in new tab) | People | Completed. Randomized, compared with placebo | A signal of benefit was reported. The product was not approved |
| Study of how thymosin beta-4 acts in skin healing | Animals | Published | It supports a role for thymosin beta-4 in cell movement during tissue repair |
Both human trials tested the pharmaceutical-grade protein. Neither tested a vial sold as TB-500.
How we count a trialIs TB-500 safe?
Nobody knows. No human trial has tested a product sold as TB-500, so no trial has measured its safety in people. The trials on this record used pharmaceutical-grade thymosin beta-4, and the record lists no safety results from them. Products sold under the TB-500 name are unregulated and unverified in what they hold. With this name, the safety question starts with what is in the vial, and that section comes after the legal one.
Is TB-500 legal?
- United States
- Not approved by the FDA. No standard chemical identity stands behind the name, and it is not a formal pharmaceutical product.
- European Union
- No marketing authorisation from the EMA.
- Sport
- Banned in sport at all times. WADA's Prohibited List names it.
- Trial products
- Company programs tested pharmaceutical-grade thymosin beta-4 in people, and none reached approval.
Not medical advice. Approval and sport status as of . Medical disclaimer
What is in a vial sold as TB-500?
Products sold as TB-500 are unregulated and unverified in what they hold, and no agreed chemical identity stands behind the name. None of the trials above tested a product sold under it. A "research use only" label guarantees nothing about purity. A certificate of analysis counts only if it names your lot number, a lab with no stake in the result, and the method used. Purity and identity are separate tests.
Three questions to ask the seller:
- Which lot number is this certificate for?
- Who ran the test, and are they independent of you?
- Does the report confirm identity by mass spectrometry, or purity alone?
What don't we know?
- Whether any product sold as TB-500 does anything in people. No human trial has tested one.
- What chemical the name stands for. No agreed identity sits behind the label.
- Whether results from pharmaceutical-grade thymosin beta-4 carry over to products sold as TB-500.
- What is in any given vial with this label.
The other side
A personal result is real to the person who had it. With no agreed identity behind the name, it cannot show which chemical was in the vial, or whether the body would have mended on its own.
What would change this record?
- A published human trial, completed and large enough to give an answer, of a chemically verified, standard peptide identical to what is sold as TB-500.
- A submission to a regulator built on that trial.
Three questions to ask next
- What does 'research use only' actually mean?
- How can you tell if a peptide vendor is legitimate?
- How do you read a certificate of analysis?
Ask better questions.
More questions about TB-500
Is TB-500 the same as thymosin beta-4?
- Not exactly. TB-500 is a seller's name used loosely for lab-made thymosin beta-4 or for a piece of it. No agreed chemical identity stands behind the name. The registered human trials used full-length, pharmaceutical-grade thymosin beta-4.
Is TB-500 approved by the FDA?
- No. No product sold as TB-500 has been approved by the FDA, and none has an EMA marketing authorisation.
Is TB-500 banned in sport?
- Yes. WADA's Prohibited List names it, and the ban applies at all times.
Has TB-500 been tested in people?
- Not in a trial. No human trial has tested a product sold under this name. All registered human trials used full-length, pharmaceutical-grade thymosin beta-4 in company programs, and none of those reached approval.
What is TB-500 made of?
- Nobody can say from the label alone. The name is used for lab-made thymosin beta-4 or for a smaller piece of it, and products sold under it are unverified in what they hold.
Record checked on . Each source shows the date it was checked.
In the same group
Often confused with Thymosin beta-4 (TB4). Thymosin beta-4 is the protein that trials tested in pharmaceutical-grade form, and TB-500 is a seller's name for it or a piece of it, with no agreed chemical identity.