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Beginner's Guide to Research Peptides
Peptides are short chains of amino acids. Some occur naturally in the body, some are modified versions of them, and some exist only in laboratories. This guide gives you the vocabulary you need before you open any protocol.
What a peptide is
Amino acids link together into chains. A chain of roughly two to fifty is usually called a peptide; longer chains are called proteins. Insulin, with 51 amino acids, sits right on the border, which is why the line is fuzzy.
Most research peptides are signalling molecules. They bind a receptor, the receptor tells a cell what to do, and the effect fades as enzymes break the peptide down. Half-lives are often minutes to hours, which is why dosing frequency matters so much.
The main families you will see
| Family | What the research is about | Examples |
|---|---|---|
| Growth hormone secretagogues | Stimulating the pituitary to release growth hormone | Ipamorelin, CJC-1295, tesamorelin |
| GLP-1 and related agonists | Appetite, blood glucose and body weight | Semaglutide, tirzepatide, retatrutide |
| Repair and recovery peptides | Tissue healing and inflammation in animal models | BPC-157, TB-500 |
| Melanocortins | Pigmentation and sexual function | Melanotan II, PT-141 |
| Nootropic peptides | Cognition and neuroprotection | Semax, Selank |
| Cosmetic peptides | Skin, usually applied topically | GHK-Cu, Argireline, Matrixyl |
Why the route of administration matters
Peptides are digested like any other protein, so most cannot survive being swallowed. That is why many are injected under the skin (subcutaneous). A few are designed for another route: some nasal sprays, topical creams, or oral compounds such as MK-677, which is a small molecule rather than a true peptide.
Always check the route on a compound page before you read the dose. A cosmetic peptide that is applied to the skin is not interchangeable with an injectable of a similar name.
How a typical protocol is built
- Vial size: how many milligrams of freeze-dried powder are in the vial.
- Reconstitution: how much sterile liquid is added to dissolve it, which sets the concentration.
- Dose: the amount per administration, usually in micrograms (mcg) or milligrams (mg).
- Frequency: how often, such as daily, twice weekly or once weekly.
- Phases: many protocols start low and step up, then rest. See the titration guide for how that works.
Evidence: how much weight to give a claim
Only a handful of peptides have large human trials behind them, mostly the GLP-1 family and a few hormone analogues. Many popular research peptides are supported by cell or animal studies only. A result in mice is a reason to be curious, not a reason to expect the same effect in people.
When you read a compound page, look for the research areas, the notes on evidence, and whether the compound is approved for any use. If there is no approval and no human data, treat dose figures as reference values reported by others, not as recommendations.
Crestigen is an educational reference. Many compounds listed here are not approved for human use. Talk to a licensed clinician before using any substance.
A sensible way to use this site
- Find the compound on the peptide list and read its description and notes first.
- Read the reconstitution guide so the mixing steps make sense.
- Use the dosage calculator to turn a dose into syringe units, and double-check the result by hand once.
- Use the syringe simulator to practise the arithmetic until the numbers feel obvious.
Common questions
Are peptides the same as steroids?
No. Peptides are short amino-acid chains that act as signals. Anabolic steroids are fat-derived molecules that act on androgen receptors. They are different classes of compound with different risks.
Why are doses written in micrograms?
Many peptides are active at very small amounts. One milligram is 1,000 micrograms, so a 250 mcg dose is a quarter of a milligram.
Is a research peptide safe to use on myself?
Safety depends on the compound, its purity and the person. Many have no human safety data at all. This site cannot assess your situation; a licensed clinician can.
Try it
- Dosage Calculator: Vial size, water and dose in; mL and syringe units out, plus doses per vial.
- Peptide Dosage Chart: Protocols for 100+ peptides, searchable by name and goal.