Peptide therapy
TB-500: what to know
Medical review pending · Last updated
Regulatory status: Compounding under HHS interim policy (not FDA-approved). TB-500 is not FDA-approved for any use. In April 2026 FDA removed it from the 503A "Category 2" (significant safety risk) list after its nomination was withdrawn; in July 2026 FDA's Pharmacy Compounding Advisory Committee voted to recommend adding it to the 503A Bulk Drugs List; and on October 28, 2026 HHS announced an interim policy (published in the Federal Register on October 30, 2026, 91 FR 68526) stating it does not intend to take enforcement action against licensed pharmacies and physicians that compound it when ten specific conditions are met (FDA-registered API source with a valid certificate of analysis, single active ingredient, specified routes, adverse-event reporting, and a patient-specific prescription, among others). The policy is non-binding, formal rulemaking has not been completed, and HHS may revise it if safety concerns arise.
What is TB-500?
TB-500 is a synthetic fragment (LKKTETQ) related to thymosin beta-4, a naturally occurring protein. Human clinical evidence is limited.
Who it may be for
Only adults for whom a licensed provider, after evaluation and informed consent, decides a compounded peptide is appropriate. Not for use in pregnancy, breastfeeding, active cancer, or by minors.
How it is given
Subcutaneous or intramuscular injection (routes covered by the HHS interim policy).
Safety considerations
- Long-term human safety data are limited.
- Compounded drugs are not reviewed by FDA for safety, effectiveness, or quality.
- Avoid "research use only" products sold online; they are not intended for human use.
- Report side effects to your provider and to FDA MedWatch.
Any prescription is at the sole discretion of a licensed provider after evaluation. Metabcore does not make claims that TB-500 treats, cures, or prevents any disease beyond FDA-approved labeling.
Read next: Are peptides legal in 2026?
Frequently asked questions
Is TB-500 legal to prescribe in 2026?
Under the HHS interim policy announced October 28, 2026 and published in the Federal Register on October 30, 2026, a licensed provider may prescribe TB-500 compounded by a state-licensed pharmacy that meets the policy's conditions. It is not FDA-approved, and the policy is interim pending rulemaking.
Is TB-500 FDA-approved?
No. TB-500 is not an FDA-approved drug for any condition.
Sources
- Federal Register: HHS Enforcement Discretion Policy Regarding 503A Compounding Using Certain Peptide Bulk Drug Substances (91 FR 68526, published Oct 30, 2026)
- HHS: Enforcement discretion policy text and Appendices A-B (PDF)
- FDA: Pharmacy Compounding Advisory Committee meeting, July 23-24, 2026
- FDA: Bulk drug substances nominated for use in compounding under section 503A (Categories 1-3, PDF)
- FDA: Compounding and the FDA, questions and answers
Sources are listed for reference and do not imply endorsement. Regulatory status can change; check the date above.
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