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Who we are

Inside Peptides is an independent reference on peptide science, evidence and regulation. We do not sell or recommend products, carry affiliate links, or give dosing information. Claims link to PubMed, FDA, ClinicalTrials.gov or other primary sources, and every profile is graded on the Inside Peptides Evidence Scale, a published, versioned five-grade scale. Read our editorial policy, funding disclosure and corrections policy.

Numbers you can cite

From the State of Peptide Research 2026 report (PDF, data in Excel). Each links to the finding and its method.

1. 13 of 24

   Thirteen of the twenty-four peptides we profile that are not FDA approved have never had an interventional trial registered on ClinicalTrials.gov.

   Source and method →
2. 0 of 24

   None of the twenty-four unapproved peptides has strong human evidence. Twenty-one rest on small early human studies, animal and lab work, or too little data to grade.

   Source and method →
3. 57%

   Two drugs, semaglutide and tirzepatide, account for 57% of the 652 active trials across the 51 peptides we track. Metabolic peptides account for 79%.

   Source and method →
4. 7 of 24

   Only seven of the twenty-four unapproved peptides have a trial under way, 19 active trials in total.

   Source and method →
5. 42% vs 11%

   42% of completed trials of approved peptide medicines have results posted on ClinicalTrials.gov, compared with 11% for investigational peptide drugs. Posted is not the same as published.

   Source and method →
6. 14 of 24

   Fourteen of the twenty-four unapproved peptides fall under the WADA Prohibited List, banned in sport at all times.

   Source and method →

Background on topics in the news

• FDA safety concerns for compounded BPC-157

  What FDA says about compounded BPC-157 safety gaps, immunogenicity, peptide impurities, and substance-specific regulatory context.

  Updated 9 October 2026
• SURMOUNT-5: tirzepatide compared with semaglutide

  A source-backed summary of SURMOUNT-5, including its obesity study population, 72-week comparison, and limits of interpretation.

  Updated 9 October 2026
• Peptides and WADA’s prohibited list: S0 and S2

  Understand where BPC-157 and peptide hormones appear in WADA’s prohibited list, and why athletes must check the applicable list and rules.

  Updated 9 October 2026
• Wegovy: FDA’s cardiovascular risk-reduction indication

  The March 2024 FDA cardiovascular indication for Wegovy, including the specific adult population and limits of generalizing approval.

  Updated 9 October 2026
• FDA-Approved Peptide Drugs vs Research Peptides

  Compare approved peptide medicines, clinical-trial products, compounded drugs and research peptides. Verify U.S. approval, product quality and evidence limits.

  Updated 10 October 2026
• Compounded Peptides

  Are compounded peptides legal? How 503A and 503B pharmacies work, which peptides FDA flags as risky to compound, and why compounded is not approved.

• What Does Research Use Only Mean on Peptide Labels?

  What a research-use-only peptide label means, why it does not make a product safe or legal for people, and how FDA judges intended human use.

  Updated 10 October 2026
• WADA Peptide Rules

  Which peptides are banned in sport? How WADA classes S0 and S2 cover BPC-157, TB-500, growth hormone secretagogues and other unapproved peptides.

Common mistakes in peptide coverage

These errors come up repeatedly in news and social media coverage of peptides. Each links to the page where we set out the evidence.

Current status for every peptide, with sources, is in the regulatory status tracker.

1. "Research use only" does not mean safe or legal for people.

   The label describes how a seller says a product may be used; it is not a quality standard or an approval. FDA looks at how a product is actually marketed and used. See what research use only means.

2. Compounded is not the same as FDA approved.

   Compounding pharmacies can prepare medicines under specific rules, but compounded products are not reviewed by FDA for safety, effectiveness or quality the way approved drugs are, and FDA has flagged some peptides as risky to compound. See compounded peptides.

3. An animal result is not a human result.

   Many popular peptides are supported mainly by rodent or cell studies. Effects in animals often fail to appear in people. See human vs preclinical research.

4. A registered trial is not evidence that a peptide works.

   Registration shows that a study was planned. Check whether it finished and what it found before describing a peptide as "in clinical trials". See the trial tracker.

5. Approval covers a product and a use, not an ingredient.

   An approval applies to a specific medicine, formulation and indication. A product with the same ingredient name, or the same drug used for something else, is not covered by it. See what FDA approval means.

6. Weight-loss percentages from different trials cannot be ranked.

   Trials differ in population, length, placebo response and analysis method. Only head-to-head trials can show one drug outperforms another. See multi-receptor agonists and the GLP-1 drug comparison.

7. A certificate of analysis is not proof of safety.

   A certificate reports tests on one sample. It may not show sterility, endotoxin levels or the identity of every impurity, and it does not make a product approved. See what a certificate of analysis can prove.

8. "Not named by WADA" does not mean allowed in sport.

   The Prohibited List includes catch-all sections, so unapproved substances can be banned without being named. See WADA peptide rules.

Key mechanisms, defined

Short definitions from our mechanism guides. Each guide explains the science in full, with sources.

Incretin effect

The amplification of insulin secretion that occurs when glucose is taken by mouth compared with an intravenous glucose infusion that produces the same blood glucose levels, attributed mainly to the gut hormones GLP-1 and GIP.

Multi-receptor agonist

A drug designed to activate two or more different hormone receptors; a dual agonist activates two (for example GLP-1 and GIP receptors) and a triple agonist activates three (for example GLP-1, GIP and glucagon receptors).

Biased agonism (functional selectivity)

The ability of a ligand to activate some of a receptor's signaling pathways more than others, measured relative to a reference ligand acting on the same receptor in the same system.

Melanocortin receptors

A family of five G protein-coupled receptors (MC1R–MC5R) activated by peptides derived from pro-opiomelanocortin, which regulate functions including pigmentation, adrenal steroid production, energy balance and sexual responses.

Growth hormone secretagogue

A substance that stimulates the pituitary gland to release the body's own growth hormone, acting through either the GHRH receptor or the ghrelin receptor (GHS-R1a).

Stratum corneum

The outermost layer of the skin, made of flattened dead cells embedded in layers of fats; it is the main barrier that stops substances on the skin surface from entering the body.

Blood–brain barrier (BBB)

The barrier formed by the cells lining the brain's capillaries, joined by tight junctions, that controls which substances pass from the blood into brain tissue.

Explainers and definitions

Our Learn guides and glossary explain the science in plain English, from what FDA approval means to "research use only" labels. Each section heading can be linked directly. Peptide-by-peptide facts, with sources, are in the peptide library and the evidence grid.

Using our material

• Data from our datasets is free to reuse under CC BY 4.0: credit Inside Peptides and link to the source page.
• Quoting short passages with a link is welcome. Please quote the source we cite for medical claims as well, not only us.
• We do not comment on individual products or sellers, or give advice about personal use.
• Found an error? Tell us through the corrections policy. Corrections to the report are logged on the report page with the date and, if you wish, credit to the person who found them.