Peptides Reference · Start Here
Peptides 101
The essentials of working with research peptides, from what they actually are to how you store, reconstitute, and measure a dose. Read this once and the rest of the database makes sense.
In Brief
Peptides are short chains of amino acids that act as precise biological signals. Most research peptides arrive as a freeze-dried powder that you reconstitute with bacteriostatic water before drawing a measured dose into an insulin syringe.
This page explains the shared fundamentals (supply, reconstitution, dosing units, storage, routes, and cycling) so the individual peptide profiles can stay focused on what makes each one different. Nothing here is medical advice; everything on this site is reference material for educational purposes only.
What are peptides?
A peptide is a short chain of amino acids, the same building blocks that make up proteins, just in a much shorter sequence. The line between “peptide” and “protein” is fuzzy, but peptides are generally under ~50 amino acids and don’t fold into the large, complex three-dimensional shapes that full proteins do. Insulin (51 amino acids) and glucagon (29) are familiar naturally-occurring examples; most research peptides on this site are 3–43 amino acids long.
Because they’re small and sequence-specific, peptides can act as highly targeted signaling molecules: chemical messages that tell cells to do something specific, such as repair tissue, release a hormone, or modulate inflammation. That precision is what makes them interesting to researchers: in principle, a peptide can nudge one pathway without the broad, system-wide effects of a small-molecule drug.
How they work
Most peptides work by binding to receptors on the surface of cells, like a key fitting a specific lock. When a peptide binds its receptor, it triggers a cascade of activity inside the cell. Because the “lock” is specific, the effect is relatively targeted.
They carry a message
Peptides don’t usually “do” the work themselves; they instruct cells to act, such as releasing growth hormone or migrating to a wound.
They’re targeted
A peptide tends to fit one receptor type, so its effects are narrower than broad-acting small-molecule drugs, at least in theory.
Most break down fast
The body’s enzymes clear most peptides quickly. Chemical modifications (like the fatty-acid chain on semaglutide) can extend this from minutes to days.
Usually injected
Stomach enzymes destroy most peptides, so they’re typically given by subcutaneous injection. A few (like BPC-157) are unusually stable and studied orally.
How they’re supplied
Research peptides almost always ship as a lyophilised (freeze-dried) powder sealed in a small glass vial, because the dry form is far more stable than a liquid during shipping and storage. The label states the total amount of peptide in the vial, commonly 5 mg or 10 mg, though it varies.
That powder is not ready to use. Before it can be measured and injected, it has to be dissolved (reconstituted) in a sterile liquid. The amount of liquid you add determines the concentration, which in turn determines how far you draw the syringe for a given dose. That relationship is the single most important thing to understand, and it’s covered next.
Reconstitution
Reconstitution means adding a measured volume of bacteriostatic water (BAC water, sterile water with 0.9% benzyl alcohol that suppresses bacterial growth across multiple uses) to the powder vial. Add the water slowly down the inner wall of the vial, then swirl gently to dissolve; never shake, as agitation can damage the peptide.
The math is simple: concentration = peptide amount ÷ water volume. For example, a 10 mg vial reconstituted with 2 mL of BAC water gives 5 mg/mL. The more water you add, the more dilute the solution, and the larger the volume you’ll draw for the same dose.
You don’t have to do this math by hand. Our Reconstitution Calculator takes your vial size, water volume, and intended dose, then shows the exact volume to draw and marks it on a syringe diagram.
Reading your dose: mcg, mg & “units”
This is where most newcomers get confused, so it’s worth getting straight. There are two different things being measured, and they are not the same:
mcg / mg: amount of peptide
How much actual peptide you’re taking. 1 milligram (mg) = 1,000 micrograms (mcg). A “0.5 mg” dose and a “500 mcg” dose are identical.
“Units”: a volume mark
The numbers on an insulin syringe measure liquid volume, not peptide. On a U-100 syringe, 100 units = 1 mL, so 10 units = 0.1 mL.
Your dose in mg is fixed by the protocol. The number of units you draw depends entirely on how you reconstituted the vial. Example: a 10 mg vial in 2 mL of water (5 mg/mL) means a 0.5 mg dose is 0.1 mL, which is 10 units on a U-100 syringe. Reconstitute the same vial with more water and that same 0.5 mg dose lands on a different unit mark.
Bottom line: never assume “units = dose.” Always convert through your specific concentration. The calculator does this for you on every peptide page and on the standalone Calculator.
Storage & handling
Peptide stability depends heavily on temperature, light, and whether the vial has been reconstituted. General handling conventions:
Lyophilised powder (unmixed)
Most stable form. Often fine at room temperature for short periods, but cold storage extends shelf life. For long-term, many are kept frozen at −20°C.
Reconstituted (liquid)
Far more delicate. Refrigerate at 2–8°C, away from light, and typically use within ~4 weeks. Do not freeze a reconstituted vial unless specifically indicated.
Light & agitation
Keep vials out of direct light and never shake; swirl gently. Mechanical stress and UV can both degrade the peptide structure.
Labelling
Mark the reconstitution date on the vial. It’s the simplest way to track how long a liquid vial has been in use.
Administration routes
How a peptide is delivered affects how fast and where it acts. These are the routes you’ll see referenced across the database.
Subcutaneous (SC)
Injection into the fat layer just under the skin, usually the abdomen, using a short, fine insulin needle. The default for most research peptides, easy to self-administer with slow, steady absorption.
Intramuscular (IM)
Injection directly into muscle, giving faster systemic absorption than SC. Used for some musculoskeletal and recovery applications. Requires a longer needle and slightly more technique.
Oral & Intranasal
A minority of peptides are stable enough for oral capsules (e.g. BPC-157) or are delivered as a nasal spray (e.g. Semax, Selank). Most peptides cannot survive the gut, which is why injection dominates.
Cycling & timing
Many protocols are structured in cycles: a period “on” the peptide followed by a period “off.” The rationale varies: giving receptors a rest to limit desensitisation, mirroring how a compound was dosed in studies, or simply limiting total exposure where long-term safety data is thin.
You’ll also see two-phase schedules. A loading phase uses more frequent dosing up front to build up tissue levels, followed by a lower-frequency maintenance phase. Approved drugs like semaglutide instead use a titration, starting low and stepping the dose up every few weeks to limit side effects. Each peptide’s profile spells out its own pattern, and many include an “Add protocol to calendar” button that schedules the whole cycle for you.
Sourcing & quality
Research peptides are sold “for research use only” and are not regulated as medicines. That means quality control is entirely on the buyer, and it varies enormously between suppliers. Products have been found mislabelled, under- or over-dosed, or contaminated.
Third-party testing
Reputable suppliers publish independent lab analyses (HPLC for purity, mass spec for identity). No certificate of analysis is a red flag.
“Research use only” is literal
This label means the product is not manufactured, tested, or approved for human use. It is a legal and regulatory statement, not a wink.
Purity & reconstitution
Look for stated purity (often ≥98%). Use proper bacteriostatic water and sterile technique; the cleanest peptide is only as safe as its handling.
Legality varies
Approval and legal status differ by peptide and country, and many are banned in competitive sport by WADA. Check your own jurisdiction.
Glossary
Frequently asked questions
What’s the difference between a peptide and a protein?
It’s a matter of size and structure. Peptides are short amino-acid chains (typically under ~50) that don’t fold into the large three-dimensional shapes proteins do. Proteins are longer and structurally complex. The cutoff is a convention, not a hard rule.
Why are most peptides injected instead of taken as a pill?
The digestive system breaks down most peptides before they can reach the bloodstream. Subcutaneous injection bypasses the gut. A few unusually stable peptides (such as BPC-157) have been studied orally, and some are delivered intranasally.
How do I know how far to draw the syringe?
It depends on your concentration, which depends on how you reconstituted the vial. Convert your dose (in mg) through the concentration to get a volume, then read that volume in units on your syringe. The Reconstitution Calculator does this automatically.
How long does a reconstituted vial last?
As a general guideline, refrigerated at 2–8°C and kept out of light, many peptides are used within about four weeks of reconstitution. Always label the vial with the date you mixed it, and follow any peptide-specific guidance.
Are research peptides safe or legal?
They are sold “for research use only” and are not approved or regulated as medicines in most jurisdictions. Long-term human safety data is limited for many, quality varies by supplier, and legal status differs by peptide and country. This site is reference material only and does not advise on use.
Important: This page is educational and reference-only. The peptides discussed across this site are not approved for human use in most jurisdictions. Nothing here is medical advice. Always follow applicable laws and institutional guidelines, and consult a qualified professional before making health decisions.