Is TB-500 legal?

TB-500 is not FDA-approved, has no USP monograph, is not part of any approved drug, and is not on the bulks lists that let pharmacies compound from it. In its briefing for the July 2026 advisory committee, the FDA proposed not adding it to the 503A list. On October 30, 2026, HHS published a draft policy that names TB-500 among six peptides for which it does not intend to take enforcement action against state-licensed pharmacies and licensed physicians compounding under section 503A, on a patient-specific prescription and under the policy's conditions. That is enforcement discretion, not approval. It does not cover 503B outsourcing facilities or TB-500 sold as a "research chemical" for people to use.

TB-500 and federal drug policy: the record

Date	What happened	Source
2011	A veterinary TB-500 preparation is marketed to boost performance in equine and greyhound sports (as the FDA's 2026 briefing reports)	FDA briefing, p. 21
June 12, 2023	FDA warning letter to an online "research purpose only" seller calls its BPC-157 and TB-500 products new drugs	FDA warning letter
September 29, 2023	FDA places TB-500 in Category 2 of its 503A interim policy (significant safety risks)	FDA safety-risk page
April 2026	The only nominator, Wells Pharmacy Network, withdraws its nomination	Regulations.gov
April 22, 2026	FDA moves TB-500 to a "nominated but withdrawn" table. It is not placed in Category 1	FDA safety-risk page
May 15, 2026	FDA staff evaluation: the criteria "weigh against" listing; FDA proposes not adding TB-500 or TB-500 acetate to the 503A list	FDA briefing, p. 34
July 23-24, 2026	The Pharmacy Compounding Advisory Committee votes to recommend listing TB-500, reported as 8 to 6 with one abstention	FDA meeting page
October 30, 2026	HHS publishes a draft enforcement-discretion policy whose Appendix A lists TB-500 with BPC-157, epitalon, KPV, MOTS-c and Semax; 503A compounding only	91 FR 68526; HHS policy

Who may supply TB-500, as of November 2, 2026

Channel	Status
503A pharmacy or licensed physician, patient-specific prescription, within the HHS policy's conditions	HHS does not intend to take enforcement action (draft policy)
503B outsourcing facility	Not covered by the HHS policy; TB-500 is not on the 503B list
Seller of "research use only" TB-500 to consumers	Unapproved new drug when the seller's site shows human use
FDA-approved product	None exists
Athletes in tested sport	Prohibited by the World Anti-Doping Agency (S2.3), as the FDA's briefing notes

What TB-500 is, in the FDA's words

The FDA describes TB-500 as "a seven amino acid synthetic fragment of thymosin beta-4 (β4) from amino acids 17 to 23" with an acetyl group added at one end. It also points out that "TB-500 is a common name and not a United States Adopted Name", and that it has found multiple salts and derivatives, including different active moieties, "sold commercially under the same common name" (FDA briefing, p. 8).

Many websites treat TB-500 and thymosin beta-4 as the same thing. The FDA does not: "thymosin beta-4 and TB-500 are not the same substance" (p. 21, note 35). The naming matters legally as well as chemically. A policy, a prescription or a supply agreement covers a named substance, and the FDA warns that inconsistent naming means a patient "may be dosed with a different BDS than the physician ordered".

Why TB-500 has no ordinary compounding route

A pharmacy compounding under section 503A may use a bulk ingredient only if it has a USP or National Formulary monograph, is a component of an FDA-approved drug, or is on the FDA's 503A bulks list (21 U.S.C. 353a(b)(1)(A)). The FDA's briefing is direct: "There is no applicable United States Pharmacopeia (USP) or National Formulary (NF) drug substance monograph for TB-500 (free base) or its acetate form, and neither is a component of an FDA-approved drug" (p. 7). The 503A list at 21 CFR 216.23 has no peptides, and neither does the 503B list.

That left the FDA's interim categories. TB-500 sat in Category 2 from September 29, 2023. After its nomination was withdrawn, the FDA moved it on April 22, 2026 to a table of substances "nominated but withdrawn", where its entry still says the FDA "has not identified any human exposure data" for drug products containing it and "lacks important information regarding any safety issues raised by this drug" (FDA safety-risk page).

The FDA's 2026 evaluation and the advisory committee

Although the nomination had been withdrawn, the FDA evaluated TB-500 and TB-500 acetate on its own initiative for the use the nominator proposed, wound healing, as a 3 mg/mL powder for injection under the skin or into the muscle. The briefing reports that the FDA found no articles in which TB-500 was given to humans, no studies of TB-500 as a compounded drug, and no outsourcing facility that had reported compounding it (pp. 7, 21-22). It concluded that the criteria "weigh against" listing and proposed "not adding TB-500 (free base) or TB-500 acetate to the 503A Bulks List" (p. 34).

The Pharmacy Compounding Advisory Committee met on July 23 and 24, 2026 and, by a vote news outlets reported as 8 to 6 with one abstention, recommended listing it anyway. The FDA had not posted minutes on the meeting page as of November 2, 2026. A committee vote is advice; it does not put a substance on the list, and adding one takes rulemaking.

What the October 30, 2026 HHS policy means for TB-500

TB-500 is one of the six peptides in Appendix A of HHS's draft "Enforcement Discretion Policy Regarding 503A Compounding Using Certain Peptide Bulk Drug Substances" (91 FR 68526; policy on hhs.gov). HHS says it does not intend to take enforcement action against a state-licensed pharmacy, federal facility or licensed physician compounding with a listed peptide, if the policy's conditions are met. They include a patient-specific prescription, a single listed peptide per product, bulk ingredient from an FDA-registered facility with a valid certificate of analysis, reporting serious adverse events and product-quality problems, and the label "This is a compounded drug product. Not for resale." The policy also names the dosage forms it covers for each peptide; read Appendix A before relying on it.

The limits are the same as for BPC-157. HHS, not the FDA, issued it, and the FDA's own staff had proposed against listing TB-500. The notice calls it a draft and says it "is not binding on HHS or the public"; HHS may revisit it "if, among other things, a safety signal or product quality issue arises". It does not cover 503B outsourcing facilities, so a clinic cannot buy TB-500 as office stock under it, and it does not cover research chemicals. More in Is BPC-157 legal?

"Research use only" TB-500

The FDA's briefing found websites selling TB-500 as 2 mg to 15 mg powders that "state that the products are intended for research use only" (p. 22). A label does not decide intended use: the FDA looks at labeling, advertising and "the circumstances surrounding the distribution" (21 CFR 201.128). In 2023 it told one online seller that its BPC-157 and TB-500 products were new drugs: "Despite statements on your product labeling marketing your products for 'research purpose only' and 'not for human consumption,' evidence obtained from your website establishes that your products are intended to be drugs for human use" (warning letter).

In April 2026 a federal grand jury in Utah indicted a physician who allegedly obtained peptides from China that he knew were not FDA-approved, TB500 among them, and sold them to his patients (DOJ, D. Utah). An indictment is an allegation, not a finding of guilt. More in Research-use-only peptides.

Athletes, North Carolina and next steps

The FDA's briefing notes that "TB-500 is on the list of prohibited substances under section S2.3 of the WADA", the World Anti-Doping Agency (p. 22). That applies to athletes in tested sport whatever HHS does.

The HHS policy is federal. North Carolina's Board of Pharmacy lets a pharmacy dispense a compounded drug only on a valid prescription, bars offering compounded drugs to others for resale, and allows office-use compounding only as federal law permits (21 NCAC 46 .2801). We have found no Board statement on the HHS policy as of November 2, 2026. A North Carolina clinic or pharmacy should confirm its position before adding TB-500; see peptide law for clinics and pharmacies.

Common questions

Update log

• November 2, 2026. Published. The FDA's TB-500 briefing, safety-risk page and meeting page, the Federal Register notice, the HHS policy's Appendix A and the Justice Department release checked November 2, 2026. The July 2026 vote count is as reported in the news; the FDA has not posted minutes.

Sources

• FDA, Evaluation of TB-500-related Bulk Drug Substances, briefing for the Pharmacy Compounding Advisory Committee (memo dated May 15, 2026)
• FDA, July 23-24, 2026 Pharmacy Compounding Advisory Committee meeting
• FDA, Certain Bulk Drug Substances That May Present Significant Safety Risks (current as of April 22, 2026)
• HHS, Enforcement Discretion Policy Regarding 503A Compounding Using Certain Peptide Bulk Drug Substances, 91 FR 68526 (Oct. 30, 2026)
• HHS, the policy with Appendix A (peptides covered), hhs.gov PDF (read November 2, 2026)
• 21 U.S.C. 353a (section 503A)
• 21 CFR 216.23 (503A bulks list)
• FDA, 503B Bulk Drug Substances List
• 21 CFR 201.128 (intended use)
• Withdrawal of the Wells Pharmacy Network nomination (Regulations.gov)
• FDA warning letter, Warrior Labz SARMS (June 12, 2023)
• U.S. Attorney's Office, D. Utah, physician indicted over misbranded drugs from China (April 1, 2026)
• 21 NCAC 46 .2801 (North Carolina compounding rule; Cornell LII copy)

Related

• Peptide attorney in Charlotte, NC
• Are peptides legal?
• Is BPC-157 legal?
• Research-use-only peptides
• 503A vs 503B

Published November 2, 2026; updated November 2, 2026. General information, not legal advice. See the disclaimer.