Wondering which peptides do what? This guide breaks down common peptides, their reported roles, safety notes, and what research actually shows.
There is no single answer to "which peptides do what" because peptides are a broad class of short amino acid chains, and each one interacts with different receptors, enzymes, and tissues. A few, like semaglutide and tirzepatide, are FDA-approved prescription drugs with large human trials behind them, while many others are sold as research chemicals with mostly animal or lab data. The guide below groups commonly discussed peptides by their reported area of interest so you can compare them in one place.
What Peptides Are and Why They Matter
Peptides are chains of roughly 2 to 50 amino acids joined by peptide bonds. Your body already uses them constantly as hormones, neurotransmitters, and growth signals. Insulin, oxytocin, and glucagon are all peptides.
Because peptides are short, most are digested quickly if swallowed. That is a big reason why the majority discussed for body composition, recovery, or cognition are given by injection, while cosmetic peptides are often applied to the skin.
Not every peptide is a drug or a supplement. In food science, the whey peptides meaning refers to the short fragments produced when dairy proteins are broken down during digestion, and they are studied for effects on blood pressure, satiety, and immune signaling.
- Metabolic peptides: GLP-1 and dual incretin agonists such as semaglutide and tirzepatide.
- Growth hormone secretagogues: ipamorelin, CJC-1295, sermorelin, and tesamorelin.
- Repair and recovery peptides: BPC-157, TB-500, and GHK-Cu.
- Cognitive neuropeptides: semax, selank, and cerebrolysin.
- Cosmetic peptides: copper peptides, matrixyl, and argireline.
Comparison Table: Common Peptides and Their Reported Uses
| Peptide | Category | Reported area of interest | US regulatory status |
|---|---|---|---|
| Semaglutide | GLP-1 agonist | Blood sugar control, appetite, weight management | FDA-approved (prescription) |
| Tirzepatide | GIP/GLP-1 dual agonist | Blood sugar control, weight management | FDA-approved (prescription) |
| Tesamorelin | GHRH analog | Visceral fat in HIV-associated lipodystrophy | FDA-approved (prescription) |
| BPC-157 | Repair | Tendon, gut lining, and tissue repair research | Not FDA-approved for human use |
| TB-500 | Repair | Soft tissue repair and cell migration | Not FDA-approved |
| Ipamorelin | GH secretagogue | Growth hormone release | Not FDA-approved |
| CJC-1295 | GHRH analog | Growth hormone release | Not FDA-approved |
| Semax | Neuropeptide | Focus, memory, and neuroprotection research | Not FDA-approved in the US |
| Selank | Neuropeptide | Anxiety and mood research | Not FDA-approved |
| GHK-Cu | Cosmetic and repair | Skin remodeling and wound healing | Not FDA-approved; used in cosmetics |
Peptides Grouped by What They Are Studied For
Metabolic and Appetite-Regulating Peptides
Semaglutide, liraglutide, and tirzepatide mimic gut hormones that slow stomach emptying and signal fullness to the brain. They are the most researched peptides on this list, with phase 3 trials and FDA approvals for type 2 diabetes and chronic weight management.
These are prescription medications, not over-the-counter supplements, and they can cause side effects such as nausea, vomiting, and, in rare cases, pancreatitis.
Growth Hormone-Related Peptides
Ipamorelin, CJC-1295, sermorelin, and tesamorelin stimulate the pituitary to release more growth hormone. Tesamorelin is FDA-approved for excess visceral fat in adults with HIV-associated lipodystrophy. The others are not approved for any human use in the US.
Growth hormone secretagogues are not the same as injectable HGH, and the two are frequently confused in online discussions.
Recovery, Gut, and Tissue-Repair Peptides
BPC-157 and TB-500 are the two most discussed repair peptides. BPC-157 is studied in animal models for tendon, ligament, and gut-lining healing, while TB-500 is studied for cell migration and soft tissue repair.
Almost all of the positive findings for these compounds come from rodent studies. Human trials are limited, and neither peptide is FDA-approved for human use in the United States.
Cognitive and Nootropic Peptides
Semax and selank are synthetic neuropeptides developed in Russia. If you have wondered what does semax do in the body, the research focus is on BDNF signaling, attention, and neuroprotection after stroke or ischemia.
Most published semax data comes from Russian-language studies, and the peptide is not approved by the FDA.
Cosmetic and Skin Peptides
GHK-Cu, matrixyl, and argireline appear in many serums and creams. They are marketed for collagen production, skin firmness, and fine lines, and topical use is generally considered lower risk than injection.
Cosmetic peptides often come with polished before-and-after photos, but independent clinical evidence for most of them is modest.
Injections, Reconstitution, and Bacteriostatic Water
Most research peptides ship as a lyophilized powder that must be dissolved before use. A common question is what does bac water do for peptides; the answer is that bacteriostatic water contains 0.9% benzyl alcohol, which inhibits bacterial growth so a multi-dose vial can be used over several weeks.
Reconstitution requires sterile technique, the correct diluent volume, and cold storage. Concentration mistakes are one of the most common causes of unintended dosing.
Safety, Legal Status, and How to Vet Peptide Claims
In the US, any peptide sold with claims to treat, cure, or prevent disease without FDA approval is being marketed illegally. Many online vendors label products "for research use only" as a workaround, which means buyers cannot assume purity, sterility, or accurate dosing.
A search for a list of injectable peptides and what they do will return dozens of sources with wildly different quality standards. Reddit threads labeled all peptides and what they do reddit are anecdote-heavy and often mix personal experience with vendor promotion.
Before using any peptide, check whether it has human clinical trials listed on ClinicalTrials.gov, whether it is FDA-approved for any indication, and whether a licensed healthcare professional is willing to supervise. Products marketed as cures for chronic disease are a red flag.
The peptides with the strongest evidence in the US are prescription metabolic and endocrine drugs. Everything else is experimental from a regulatory standpoint, and personal anecdotes are not a substitute for clinical data.
Frequently Asked Questions
Which peptides are FDA-approved for human use in the US?
Semaglutide (Ozempic, Wegovy), tirzepatide (Mounjaro, Zepbound), liraglutide (Victoza, Saxenda), and tesamorelin (Egrifta) are examples of FDA-approved peptide drugs. BPC-157, TB-500, ipamorelin, CJC-1295, semax, and selank are not FDA-approved for human use and are typically sold as research chemicals.
What does BPC-157 actually do?
BPC-157 is studied in animal models for tendon, ligament, and gut-lining repair, along with some anti-inflammatory effects. There are no completed large human trials, and the peptide is not FDA-approved for human use in the United States.
Do peptides really work, or is it hype?
It depends entirely on the peptide. GLP-1 drugs like semaglutide have large randomized trials showing clinically meaningful weight and blood sugar effects, while most other peptides have only animal data or small human studies. Anyone considering peptides should talk with a licensed healthcare professional first.
This page provides educational research information and does not replace medical advice, diagnosis, or treatment.