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Are Peptides Legal? A US Regulatory Overview

By BioLabs Research · Last reviewed October 2026

There is no single legal status for "peptides". This overview sets out the main US regulatory categories, with links to the primary FDA and federal sources.

There is no single legal status for peptides. Legality depends on the specific compound, what it is intended for, how it is labeled and marketed, and where it is sold. This page summarizes how US federal rules sort peptides into categories, citing the primary sources. It is general information, not legal advice.

Peptide or protein: why size matters in US law

FDA defines a protein as an alpha amino acid polymer with a specific, defined sequence of more than 40 amino acids, counting naturally associated chains together[1]. The definition sits inside FDA's definition of a biological product[1]. Insulin, at 51 amino acids across two chains[2], is the best-known case: a 2009 law set a transition from regulating insulin as a drug to regulating it as a biologic, and FDA began accepting biosimilar insulin applications on March 23, 2020[3]. BPC-157 and TB-500 are far shorter: BPC-157 has 15 residues[4] and the TB-500 fragment has 7[5].

Category 1: approved medicines

A peptide drug becomes a lawful prescription medicine when FDA approves a specific product for a specific use after clinical investigation and review[6]. Insulin is the classic example: FDA approved the first recombinant human insulin on October 28, 1982[3]. Federal law requires an effective approval for each new drug[7], so one approval does not make other peptides approved.

Category 2: unapproved drugs and "intended use"

Whether a product is regulated as a drug depends on its intended use. Under 21 CFR 201.128, intended use is the objective intent of the people responsible for the product, shown by labeling claims, advertising, oral or written statements, the design or composition of the article, and the circumstances of its distribution[8]. A new drug may not be introduced into interstate commerce without an effective FDA approval[7], so selling an unapproved compound with claims about use in people exposes the seller to enforcement, whatever the label says. This is why BioLabs Research makes no human-use claims and provides no usage guidance.

Category 3: compounding pharmacies

Section 503A of the Federal Food, Drug, and Cosmetic Act lets pharmacies compound from a bulk drug substance only if it has a USP or NF monograph, is a component of an FDA-approved drug, or appears on a list FDA develops through regulations[9]. As of the October 6, 2026 eCFR issue, that list, 21 CFR 216.23(a), names six substances, and none of them is a research peptide such as BPC-157 or TB-500[10].

FDA also publishes a page on nominated bulk substances that may present significant safety risks ("category 2")[11]. BPC-157, the TB-500 fragment, AOD-9604, CJC-1295, MOTS-c, Semax, epitalon, KPV and several others now appear in its table of substances whose nominations were withdrawn by the nominators; FDA's page retains its safety-risk descriptions for each[11]. FDA's Pharmacy Compounding Advisory Committee met on July 23–24, 2026 to discuss whether BPC-157 and TB-500 bulk drug substances, among others, should be included on the 503A list[12][13]. FDA states that advisory committees make non-binding recommendations[13]. The list itself is developed through regulations[9], and as of the October 6, 2026 eCFR issue neither substance appears on it[10].

Category 4: dietary supplements

FDA does not approve dietary supplements for safety and effectiveness[14]. FDA's directory of dietary supplement ingredients records the agency's actions on specific substances, including ingredients it considers excluded from the dietary supplement definition under section 201(ff)(3) of the FD&C Act[14]. One peptide hormone, human chorionic gonadotropin (HCG), is listed in that excluded category, with FDA warning letters to sellers of HCG products[14]. The directory itself states that it is not a comprehensive list[14].

Category 5: controlled substances and restricted hormones

Anabolic steroids are Schedule III controlled substances[15][16]; they are not peptides (see are peptides steroids?). Human growth hormone is restricted by a separate statute: knowingly distributing it for any use in humans other than an FDA-authorized use under a physician's order is a federal offense under 21 U.S.C. 333(e)[17].

Category 6: research chemicals (RUO)

Compounds supplied for laboratory research are sold on the basis that they are not for use in humans or animals and are intended for in-vitro and analytical work. A research-use-only label is not sufficient on its own: under the intended-use rule above, the seller's claims, statements and the circumstances of sale must also be consistent with research use[8].

Sports rules

Anti-doping rules are separate from criminal and drug law. The World Anti-Doping Agency's 2026 Prohibited List names BPC-157 under S0, non-approved substances, and lists thymosin-β4 and its derivatives, such as TB-500, under S2[18].

Imports, state law and institutional responsibility

Import rules, state laws and institutional policies can add requirements beyond the federal categories above, and they differ by jurisdiction. Compliance with every law and policy that applies to the purchase, possession and laboratory use of a research compound is the responsibility of the purchasing institution and its researchers.

BioLabs Research sells research compounds for laboratory research use only. We make no human-use claims, provide no usage guidance and are not a pharmacy. Product pages such as BPC-157 and TB-500 list identity data, and a lot-specific COA is available on request through our COA library. For background, see What are peptides?. This page is general information, not legal advice. Consult a qualified attorney about your specific situation.

Frequently asked questions

Are peptides legal in the US?

It depends on the specific peptide, its intended use, its labeling and the jurisdiction. Approved peptide medicines are lawful prescription products; unapproved compounds marketed for use in people are not.

Are BPC-157 or TB-500 on FDA's 503A bulks list?

Neither is on FDA's 503A bulks list in 21 CFR 216.23 as of the October 6, 2026 eCFR issue. FDA's advisory committee discussed both in July 2026; FDA describes such recommendations as non-binding, and the list itself is developed through regulations.

Are peptides allowed in dietary supplements?

FDA does not approve dietary supplements. Its ingredient directory lists human chorionic gonadotropin, a peptide hormone, as excluded from the dietary supplement definition. The directory is not comprehensive.

Does a research-use-only label make a product legal?

Not on its own. FDA judges intended use from labeling, advertising, statements and the circumstances of sale, so all of these must be consistent with research use.

Who is responsible for compliance when buying research compounds?

The purchasing institution and its researchers are responsible for complying with the federal, state and local laws and institutional policies that apply. This page is not legal advice.

For laboratory research use only. Not for human or veterinary use. Not a drug, food, cosmetic or dietary supplement, and not intended to diagnose, treat, cure or prevent any condition. Nothing on this page is medical or legal advice.

References

  1. 21 CFR 600.3(h)(6), definition of "protein" (eCFR). www.ecfr.gov/current/title-21/section-600.3
  2. UniProt Consortium. UniProtKB P01308, Insulin (human). www.uniprot.org/uniprotkb/P01308/entry
  3. US Food and Drug Administration, FDA History Office. 100 Years of Insulin. www.fda.gov/about-fda/fda-history-exhibits/100-years-insulin
  4. National Center for Biotechnology Information. PubChem Compound Summary for CID 9941957 (BPC-157). pubchem.ncbi.nlm.nih.gov/compound/9941957
  5. Esposito S, Deventer K, Goeman J, Van der Eycken J, Van Eenoo P. Synthesis and characterization of the N-terminal acetylated 17-23 fragment of thymosin beta 4 identified in TB-500 […]. Drug Test Anal. 2012;4(9):733–738. doi:10.1002/dta.1402. PMID 22962027. pubmed.ncbi.nlm.nih.gov/22962027
  6. 21 CFR 312.21, phases of an investigation (eCFR). www.ecfr.gov/current/title-21/section-312.21
  7. 21 U.S.C. 355(a), necessity of effective approval of a new drug application (US Code, GovInfo). www.govinfo.gov/content/pkg/USCODE-2023-title21/html/USCODE-2023-title21-chap9-subchapV-partA-sec355.htm
  8. 21 CFR 201.128, meaning of "intended uses" (eCFR). www.ecfr.gov/current/title-21/section-201.128
  9. 21 U.S.C. 353a(b)(1)(A)(i), pharmacy compounding: bulk drug substances (US Code, GovInfo). www.govinfo.gov/content/pkg/USCODE-2023-title21/html/USCODE-2023-title21-chap9-subchapV-partA-sec353a.htm
  10. 21 CFR 216.23, bulk drug substances that can be used to compound under section 503A (eCFR). www.ecfr.gov/current/title-21/section-216.23
  11. US Food and Drug Administration. Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks. www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
  12. Food and Drug Administration. Pharmacy Compounding Advisory Committee; Notice of Meeting… Bulk Drug Substances Nominated for Inclusion on the Section 503A Bulk Drug Substances List. Federal Register, April 16, 2026, Doc. 2026-07361. www.federalregister.gov/documents/2026/04/16/2026-07361/pharmacy-compounding-advisory-committee-notice-of-meeting-establishment-of-a-public-docket-request
  13. US Food and Drug Administration. July 23-24, 2026: Meeting of the Pharmacy Compounding Advisory Committee. www.fda.gov/advisory-committees/advisory-committee-calendar/july-23-24-2026-meeting-pharmacy-compounding-advisory-committee-07232026
  14. US Food and Drug Administration. Information on Select Dietary Supplement Ingredients and Other Substances. www.fda.gov/food/dietary-supplements/information-select-dietary-supplement-ingredients-and-other-substances
  15. US Drug Enforcement Administration. Drug Scheduling. www.dea.gov/drug-information/drug-scheduling
  16. 21 CFR 1308.13(f), Schedule III: anabolic steroids (eCFR). www.ecfr.gov/current/title-21/section-1308.13
  17. 21 U.S.C. 333(e), prohibited distribution of human growth hormone (US Code, GovInfo). www.govinfo.gov/content/pkg/USCODE-2023-title21/html/USCODE-2023-title21-chap9-subchapIII-sec333.htm
  18. World Anti-Doping Agency. The 2026 Prohibited List (in force 1 January 2026). www.wada-ama.org/sites/default/files/2025-09/2026list_en_final_clean_september_2025.pdf