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Peptides 101: What's Tested, What Isn't

What a peptide is, plus one map of eleven peptides: approved, tested in people, or barely tested.

  1. 1A peptide is a short chain of amino acids; your body makes many, including insulin and GLP-1.1,2,3
  2. 2Approved peptide drugs rest on large trials; FDA reviewers found no study giving TB-500 to people.4,5,6
  3. 3"Research use only" is a seller's label; FDA letters called such products unapproved drugs when websites showed human use.7
Read the short answer

The short answer

A peptide is a short chain of amino acids, the building blocks of proteins.1,8 Your body makes many, such as insulin and GLP-1.2,3 Some peptides are approved drugs, tested in thousands of people.4,5 Some are still in trials.9 Others have barely been tested in people, or not at all.10,6 The map below sorts five names people ask about. The PDF maps eleven.

Five names, three groups4,5,9,11,10,6,12
Semaglutide (Ozempic, Wegovy)
Group
Approved drug
Evidence in people
2,116 on Wegovy, three trials
Tirzepatide (Mounjaro, Zepbound)
Group
Approved drug
Evidence in people
2,519 on Zepbound, two trials
Retatrutide
Group
Tested, not approved
Evidence in people
Phase 3 trials; filing planned 2027
BPC-157
Group
Barely tested
Evidence in people
Five small studies, FDA found
TB-500
Group
Not tested in people
Evidence in people
No study in people, FDA found

From the drug labels, Lilly, the FDA's 2026 reviews and the Table's records. The PDF maps eleven names, with their grades.

"Research use only" is the seller's label
In 2026, FDA warning letters looked past that label. A seller's website showed its products were meant for people. So the FDA called them unapproved new drugs.7

The full PDF, free.

  • The full map: eleven named peptides in three groups, each with its evidence, its source and its grade
  • What a peptide is, and the peptides your body makes
  • What "research use only" means in the FDA's own letters, and what HHS's October policy covers
  • Four questions that test any peptide claim, plus a short glossary

A source on every line. No paid placements. No doses.

Instant download. You also get the Wednesday email, which you can leave on the first click. Privacy

The fair line
Being a peptide makes a compound neither safe nor unsafe. Approved peptide drugs carry side effects too. In three Wegovy trials, 44 in 100 people on the drug reported nausea, against 16 in 100 on placebo.4

This guide was last checked on 3 November 2026. Research and educational information only. Nothing here is medical advice.

  1. [1] NIH genome institute (NHGRI), Talking Glossary: Peptide (opens in new tab). Checked 2 Nov 2026Back to text (first mention of source 1)
  2. [2] StatPearls (StatPearls Publishing, on NCBI Bookshelf), Insulin, by Thota and Akbar, updated 10 Jul 2023 (opens in new tab). Checked 2 Nov 2026Back to text (first mention of source 2)
  3. [3] National Library of Medicine, MeSH record: Glucagon-Like Peptide 1 (D052216) (opens in new tab). Checked 2 Nov 2026Back to text (first mention of source 3)
  4. [4] Wegovy (semaglutide) label, Novo Nordisk, revised June 2026 (opens in new tab). Checked 2 Nov 2026Back to text (first mention of source 4)
  5. [5] Zepbound (tirzepatide) label, Eli Lilly, revised Aug 2026 (opens in new tab). Checked 2 Nov 2026Back to text (first mention of source 5)
  6. [6] FDA review of TB-500 for the compounding advisory committee, 15 May 2026 (opens in new tab). Checked 2 Nov 2026Back to text (first mention of source 6)
  7. [7] FDA, warning letters to two online peptide sellers, 31 Mar 2026 (posted 7 Apr) and 24 Aug 2026 (posted 1 Sep). Web addresses held back: they carry the sellers' names. Checked 2 Nov 2026Back to text (first mention of source 7)
  8. [8] National Cancer Institute, Dictionary of Cancer Terms: peptide (opens in new tab). Checked 2 Nov 2026Back to text (first mention of source 8)
  9. [9] Eli Lilly, news release on retatrutide, 29 Sep 2026 (opens in new tab). Checked 2 Nov 2026Back to text (first mention of source 9)
  10. [10] FDA review of BPC-157 for the compounding advisory committee, 11 May 2026 (opens in new tab). Checked 2 Nov 2026Back to text (first mention of source 10)
  11. [11] The Lancet, TRIUMPH-2 trial of retatrutide, Bellido and others, 29 Sep 2026 (opens in new tab). Checked 2 Nov 2026Back to text (first mention of source 11)
  12. [12] The Peptide Table, the records of all compounds (grades and counts as of 28 Oct 2026) (opens in new tab). Checked 2 Nov 2026Back to text (first mention of source 12)
  13. [13] National Library of Medicine, MeSH record: Peptides (D010455) (opens in new tab). Checked 2 Nov 2026
  14. [14] National Library of Medicine, MeSH record: Insulin (D007328) (opens in new tab). Checked 2 Nov 2026
  15. [15] National Library of Medicine, MeSH record: Peptide Hormones (D036361) (opens in new tab). Checked 2 Nov 2026
  16. [16] Holst, "The physiology of glucagon-like peptide 1", Physiological Reviews, 2007 (PubMed abstract) (opens in new tab). Checked 2 Nov 2026
  17. [17] Ozempic (semaglutide) label, Novo Nordisk, revised May 2026 (opens in new tab). Checked 2 Nov 2026
  18. [18] Mounjaro (tirzepatide) label, Eli Lilly, revised Aug 2026 (opens in new tab). Checked 2 Nov 2026
  19. [19] Egrifta SV (tesamorelin) label, on the FDA's site, 2019 (opens in new tab). Checked 2 Nov 2026
  20. [20] Vyleesi (bremelanotide) label, on the FDA's site, 2019 (opens in new tab). Checked 2 Nov 2026
  21. [21] FDA, Drugs@FDA: Ozempic, application NDA 209637 (opens in new tab). Checked 2 Nov 2026
  22. [22] HHS, notice of its peptide compounding policy, FR Doc. 2026-22192, filed 28 Oct 2026 (opens in new tab). Checked 2 Nov 2026
  23. [23] HHS, interim enforcement policy text with Appendices A and B (linked from FR Doc. 2026-22192) (opens in new tab). Checked 2 Nov 2026
  24. [24] FDA, "FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss", current as of 1 Oct 2026 (opens in new tab). Checked 2 Nov 2026
  25. [25] FDA, "Step 3: Clinical Research", current as of 4 Jan 2018 (opens in new tab). Checked 2 Nov 2026
  26. [26] US federal rules, 21 CFR 314.126 (eCFR, up to date as of 22 Oct 2026) (opens in new tab). Checked 2 Nov 2026
  27. [27] The Peptide Table, How we count a trial (Method page) (opens in new tab). Checked 2 Nov 2026
  28. [28] ClinicalTrials.gov, NCT07437547, BPC-157 for hamstring strains (opens in new tab). Checked 3 Nov 2026

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