Is TB-500 legal in the US?
The short answer
TB-500 is not an FDA-approved drug and is not on the 503A Bulks List as of 2026-07-28. On 2026-07-23, FDA's Pharmacy Compounding Advisory Committee voted to recommend adding it — but that vote is advisory. FDA must still complete rulemaking before anything changes.
The July 23-24, 2026 vote
What FDA actually evaluated
FDA assessed TB-500 for one thing: wound healing.
FDA did not review TB-500 as a sports-recovery, muscle-growth, injury-repair or performance product.
Full regulatory status
| FDA-approved drug? | No FDA-approved drug product contains TB-500 free base or acetate. TB-500 is a fragment, not full-length thymosin beta-4. |
|---|---|
| Indication FDA reviewed | Wound healing |
| PCAC recommendation | Recommended for the 503A Bulks List (advisory only) |
| FDA reviewers' position | Do not add to the 503A Bulks List. |
| Category 2 status | Previously in FDA's interim Category 2 (significant safety risk). Moved to the “nominated but withdrawn” table after the nomination was withdrawn in April 2026. Removal from Category 2 did not authorize compounding and did not move it to Category 1. |
| 503A Bulks List today | Not on the 503A Bulks List. A PCAC recommendation is advisory only — FDA must complete rulemaking before 21 CFR 216.23 changes. |
| 503B status | Not on the final 503B Bulks List, and not in FDA's published interim 503B categories. |
| Prescription status | No FDA-approved US status. Not an approved prescription or OTC drug. “Research use only” is a seller label, not authorization to administer to patients. |
| Next federal event | Possible rulemaking. No TB-500-specific date has been announced. |
If you compete in sport
Prohibited at all times, in and out of competition, as a non-specified substance. USADA has sanctioned athletes for TB-500 use.
Why FDA's own reviewers recommended against it
- Inadequate characterization and inconsistent naming
- Missing impurity, aggregate, microbial and endotoxin controls
- Potential immunogenicity
- No adequate toxicology program
- No human wound-healing efficacy evidence
- No persuasive in-vivo wound-healing evidence for TB-500 itself
- No human safety data
- Approved wound-care alternatives already available
What you can actually do today
You can seek evaluation and discuss approved wound-care options. The vote did not approve TB-500 for wound healing or sports recovery.
What would have to happen for this to change
- 1FDA completes its own evaluation. The advisory vote is non-binding — FDA can accept or reject it.
- 2FDA publishes a proposed rule in the Federal Register identifying substances proposed for inclusion or exclusion, with its reasoning.
- 3A public comment period opens. Anyone may submit evidence and scientific or legal objections.
- 4FDA reviews the comments and the administrative record.
- 5FDA publishes a final rule, or withdraws or modifies the proposal.
- 6The final rule takes effect and amends the list at 21 CFR 216.23.
Sources
See the status of all seven peptides side by side in the FDA 503A compounding tracker. Or read our full guide to TB-500.
Medical Disclaimer: This content is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare provider before beginning any peptide therapy treatment.