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Is TB-500 legal? Status in the EU, the US and in sport
By Pinnacle Pulse Editorial Team · Status as of 16 October 2026 · Next scheduled update: 14 January 2027
Short answer: TB-500 is not an authorized medicine in the EU or the US. WADA lists “thymosin-β4 and its derivatives e.g. TB-500” in class S2, so it is prohibited at all times in sport. This is general information, not legal advice.
At a glance
| Where | Status on 16 October 2026 |
|---|---|
| EU | No marketing authorization; no entry in EMA’s medicines data |
| US | Not FDA-approved; not on the 503A bulks categories; FDA reports no human exposure data |
| WADA | Class S2.3, prohibited in and out of competition, not a specified substance |
What the name refers to
Regulators and sellers don’t use the same words, so first some precision. Thymosin beta-4 is a natural protein, 43 amino acids long. TB-500 is what sellers call a synthetic product; when anti-doping chemists in Ghent analyzed one in 2012, they found an acetylated fragment of that protein, just seven amino acids long. FDA’s paperwork calls it “thymosin beta-4, fragment (LKKTETQ), also known as TB-500”. WADA’s list covers “thymosin beta-4 and its derivatives”, which catches the fragment either way.
European Union
No medicine with thymosin beta-4 or TB-500 in it has an EU marketing authorization; EMA’s medicines data have no such entry. As with BPC-157, a “for research only” label doesn’t settle whether a product counts as a medicine. EU law looks at how it is presented and what it does.
United States
FDA has never approved a drug containing TB-500 or thymosin beta-4.
TB-500 went through the same compounding saga as BPC-157. It had been nominated for the 503A bulks list; the nominations were withdrawn in 2026, and FDA dropped it from its categories. The agency’s list of withdrawn substances says FDA didn’t find any human exposure data for the fragment. Even so, TB-500 was on the agenda when FDA’s Pharmacy Compounding Advisory Committee met in July 2026, this time evaluated for wound healing, and FDA staff advised against adding it. Committee votes are only advice. As of 16 October 2026 no proposed rule for TB-500 has appeared in the Federal Register.
Sport
WADA’s 2027 Prohibited List, in force from 1 January 2027, puts “Thymosin-ß4 and its derivatives e.g. TB-500” in class S2.3, growth factors and growth factor modulators. It’s banned in and out of competition, however it’s taken. S2 substances are not “specified”, a distinction that changes how sanctions are worked out under the World Anti-Doping Code.
What the research does not show
None of these rules says anything about whether TB-500 works or is safe. FDA found no human exposure data at all. The human trials that exist used the whole thymosin beta-4 protein, as eye drops, which is a different molecule given a different way. Our article [TB-500: what the research shows](/research/tb-500) goes through it.FAQ
Is TB-500 legal in the EU?
It is not an authorized medicine in the EU. EMA’s medicines data list no product containing TB-500 or thymosin beta-4.
Is TB-500 legal in the US?
It is not FDA-approved and not on the lists of substances compounding pharmacies may use. FDA has said it identified no human exposure data for the fragment.
Is TB-500 banned by WADA?
Yes. WADA lists thymosin beta-4 and its derivatives, naming TB-500, in class S2.3. It is prohibited at all times.
Is thymosin beta-4 treated differently from TB-500?
Not in anti-doping rules. WADA covers thymosin beta-4 and its derivatives, so the full protein and the fragment fall under the same entry.
Sources
- FDA. Certain bulk drug substances for use in compounding that may present significant safety risks. fda.gov
- FDA. Bulk drug substances nominated for use in compounding under section 503A: categories. fda.gov/media/94155/download
- FDA. July 23-24, 2026: Meeting of the Pharmacy Compounding Advisory Committee. fda.gov
- FDA. FDA briefing document, Pharmacy Compounding Advisory Committee, July 2026. fda.gov/media/193342/download
- Esposito S, et al. Drug Test Anal. 2012;4:733-8. PMID 22962027
- WADA. The Prohibited List. wada-ama.org
- USADA. Athlete advisory: what’s new on the 2027 WADA Prohibited List? usada.org
- EMA. Download medicine data: table of all medicines assessed by EMA (Excel), checked 16 October 2026. ema.europa.eu
- FDA. Briefing document for TB-500-related bulk drug substances, Pharmacy Compounding Advisory Committee, July 2026, checked 16 October 2026. fda.gov/media/193349/download
- Federal Register. Search of FDA documents published since 1 April 2026 for BPC-157, TB-500 and the 503A and 503B bulks lists, run 16 October 2026: no proposed or final rule. federalregister.gov
- WADA. 2027 Prohibited List, full text (PDF), checked 16 October 2026. wada-ama.org
Facts last checked: 16 October 2026.
About this article
Written by: the Pinnacle Pulse Editorial Team, the people who make the Pinnacle Pulse app. We work only from primary sources such as regulators, legal texts, trial registries and PubMed, and we remove claims we can’t check against one.
This page has not been reviewed by a lawyer. It is general information, not legal advice.
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Change log
- 16 October 2026: First published.
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This page is general information about the law as of the date shown. It is not legal advice. For your own situation, consult a lawyer.