The short answer. TB-500 is not FDA-approved and, as of September 25, 2026, has no lawful compounding pathway. It is also not thymosin beta-4: FDA says in writing that the two are different substances, so research on the full protein does not carry over.
| FDA approved | No. No monograph, and not a component of any approved drug. |
|---|---|
| 503A pharmacy | No pathway. Not on 21 CFR 216.23 and in no category. |
| 503B outsourcing facility | No pathway. |
| Latest FDA action | Advisory committee, Jul 23, 2026 (wound healing). FDA’s briefing recommended against listing. |
| Sport | WADA prohibited (S2.3, thymosin beta-4 and its derivatives). |
| MDside position | Our providers do not prescribe it. |
| Last verified | 2026-09-25 |
TB-500 is a fragment, and FDA treats it as its own substance
TB-500 is a short synthetic fragment (the LKKTETQ sequence) derived from thymosin beta-4. Vendor pages routinely cite thymosin beta-4 research and orphan designations as if they applied to TB-500. FDA’s July 2026 briefing states that thymosin beta-4 and TB-500 are not the same substance. Full-length thymosin beta-4 sits in no 503A category either.
It followed the same path as BPC-157
FDA placed the fragment in Category 2 on September 29, 2023. The nominator withdrew in April 2026, FDA gave seven days’ notice on April 15, and the fragment left Category 2 by April 22, 2026. It now sits in no category, which means no interim-policy discretion for a 503A pharmacy. The BPC-157 page explains why leaving Category 2 is not permission.
The July 2026 advisory committee
The committee discussed TB-500 free base and acetate for wound healing on July 23, 2026. FDA proposed that neither be listed. As of September 25, 2026 FDA has not posted minutes and no rulemaking has begun. FDA also named TB-500 in its 2023 warning letter to Warrior Labz as an unapproved new drug.
What this means for you
Keep TB-500 and any BPC-157 and TB-500 blend off your menu. If a supplier’s material cites thymosin beta-4 approvals or orphan status, treat that as a sign the supplier either does not understand the product or is counting on you not to. Re-check this page before any change: a listing would require a proposed rule first, and you would see it here.
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Frequently asked questions
Is TB-500 the same as thymosin beta-4?
No. TB-500 is a synthetic fragment of the thymosin beta-4 protein, and FDA’s July 2026 briefing states the two are not the same substance. Evidence or designations for thymosin beta-4 do not transfer to TB-500, and neither sits in a 503A category.
Can a pharmacy compound TB-500?
No. As of September 25, 2026 TB-500 is not on the 503A bulks list, is in no FDA category, has no monograph and is not part of an approved drug. Its April 2026 removal from Category 2 followed a withdrawn nomination and did not open a pathway.
Is TB-500 banned by WADA?
Yes. The 2026 WADA Prohibited List names thymosin beta-4 and its derivatives, including TB-500, under S2.3. It is prohibited at all times for athletes subject to the Code, in and out of competition. Clinics serving competitive athletes should treat any TB-500 product as a doping risk as well as a compounding one.
Primary sources. Last verified September 25, 2026. Corrections are welcome: contact us.
- FDA, 503A bulk drug substance categories (updated May 14, 2026)
- FDA, Certain bulk drug substances that may present significant safety risks (updated Apr 22, 2026)
- FDA, Interim Policy on Compounding Using Bulk Drug Substances Under Section 503A (Jan 2025)
- 21 CFR 216.23, the 503A bulks list
- FDA, Pharmacy Compounding Advisory Committee, July 23-24, 2026
- FDA briefing document, TB-500 (July 2026 PCAC)
- FDA warning letter, Warrior Labz (Jun 12, 2023)
- WADA 2026 Prohibited List
This is general information, not legal advice. Rules vary by state and change. Confirm your own facts with counsel.