What Are Peptides?
Peptides are short chains of amino acids. Same building blocks as proteins, just shorter. Your body makes thousands of them. They act as signals: telling cells to release hormones, repair tissue, regulate appetite, and so on.
You already know some without the label. Insulin is a peptide. Oxytocin is a peptide. Growth hormone is technically a protein by size, but everyone still groups it with peptides in research talk.
When this site says "peptides," we usually mean synthetic versions sold as freeze-dried powder in small glass vials, labelled for laboratory research. That powder is stable. Liquid is not. That's why they ship dry.
How Do They Work?
A peptide binds to a receptor on a cell. Receptor activates. Something happens downstream. Different peptide, different receptor, different effect.
Ipamorelin hits ghrelin pathways and nudges GH release. Semaglutide hits GLP-1 receptors and affects appetite and blood sugar. BPC-157 gets studied for repair and inflammation pathways. None of this is one-size-fits-all.
What matters in practice: dose, frequency, route, and half-life. Same compound at the wrong dose or wrong schedule can do nothing, do the wrong thing, or cause side effects you didn't want. That's why protocols exist instead of guesswork.
Main Categories
You'll run into these groupings constantly:
Recovery and repair
BPC-157 and TB-500 dominate this space. Tendons, gut, general tissue repair. Often paired in blends or stacks.
Growth hormone and secretagogues
Either actual GH (HGH/somatropin) or compounds that push your pituitary to release more of its own:
- GHRH analogues (CJC-1295, Sermorelin, Tesamorelin): amplify GH pulses
- GHRPs (Ipamorelin, GHRP-2, GHRP-6): trigger release via ghrelin receptors
- MK-677: oral, not a peptide, but sits in the same conversations
CJC + Ipamorelin is the classic combo because the pathways complement each other.
Metabolic and weight
GLP-1 agonists are the big clinical story right now. Semaglutide, tirzepatide, retatrutide. Heavy research, real FDA-approved drugs in clinical use, and a lot of grey-market interest on the side.
Skin, hair, anti-aging
GHK-Cu for skin remodeling (often used topically in moisturiser). Melanotan II for pigmentation research. Epithalon and others in longevity conversations.
Hormonal and sexual health
HCG, PT-141, kisspeptin analogues. Different mechanisms, different legal status. Worth reading carefully before assuming anything is "just research."
What Shows Up in the Mail
A small glass vial. White or off-white powder at the bottom. Rubber stopper, crimp cap. Label says something like "BPC-157 5mg" or "Semaglutide 3mg."
That vial is not ready to use. You add liquid first (reconstitution). The powder stays good for months or years. Liquid starts degrading fast. Simple reason most peptides ship lyophilized.
Mixing Powder Into Liquid
Reconstitution is the first hands-on skill. Add measured BAC water to the vial. Let it dissolve. Now you have a concentration you can dose from.
You need
- Peptide vial (powder)
- Bacteriostatic water (BAC): sterile water + 0.9% benzyl alcohol preservative
- Insulin syringe (U-100, usually 1 mL or 0.5 mL)
- Alcohol swabs
Quick version
- 1
Swab the stoppers
Peptide vial and BAC vial. Let them dry a few seconds.
- 2
Draw your BAC water
How much you add sets your concentration. Write it down.
- 3
Inject slowly down the glass wall
Not straight onto the powder. Slow stream.
- 4
Swirl gently. Never shake.
Most dissolve in 1–3 minutes. Some take longer.
- 5
Label and refrigerate
Date + BAC volume on the vial. Fridge immediately.
Full walkthrough: Reconstitution Guide.
Units That Trip People Up
Three systems. They measure different things. Mixing them up is how people dose wrong by 10x or 1000x.
mg and mcg (weight)
How much peptide by mass. 1 mg = 1,000 mcg. A protocol saying 250 mcg is not the same as 250 mg. Check every time.
mL and syringe units (volume)
How much liquid you draw. On a U-100 syringe, 100 units = 1 mL. Each unit is 0.01 mL. Syringe units are volume marks. They are not peptide dose marks.
IU (potency)
Biological activity, mainly for HGH (~3 IU per 1 mg somatropin) and HCG. "2 IU" does not mean draw to the 2 on your syringe. You calculate volume from concentration.
How You Actually Use It
Most protocols assume subcutaneous injection: small insulin needle into belly fat, thigh, or upper arm. U-100 syringes, 29G–31G needles.
Some compounds go other routes. GHK-Cu often gets mixed into plain moisturiser for skin. Others get reconstituted and diluted into a nasal spray. Different routes, different math.
Injection, topical, and nasal breakdown: Deployment Methods. Calculator for all three: Dosage Calculator.
Storage
Powder (before mixing)
- Fridge at 2–8°C is ideal
- Cool, dark, dry if short-term at room temp
- Some peptides tolerate freezing while still lyophilized
- Keep away from heat, humidity, sunlight
Liquid (after mixing)
- Fridge immediately, always upright
- ~25–30 days with BAC water
- Never freeze reconstituted peptide
- Don't shake. Label with date.
More detail: Storage Guide.
Safety Reality Check
Side effects depend on the compound
Injection site redness, headache, nausea, fatigue show up across many peptides. GH-related stuff can mean water retention or joint ache. GLP-1 agonists often hit the gut first. Read the specific protocol, not generic "peptide" advice.
More is not better
Dose-response curves exist. Past a point you add side effects without adding benefit. Evidence-based ranges matter.
Research-grade is not pharmacy-grade
"For research use only" vials don't get the same manufacturing oversight as prescription drugs. Purity, sterility, and label accuracy vary. COAs help but aren't a guarantee.
Legal status varies
Some peptides are prescription drugs. Some are restricted federally. Many sit in research-chemical grey areas. WADA bans most performance-related peptides in tested sport. See the FAQ.
What You Need
- Peptide vial(s), refrigerated
- BAC water (10 mL or 30 mL vials common)
- U-100 insulin syringes, 0.5 or 1 mL, 29–31G
- Alcohol swabs
- Sharps container
- Fridge space
- Tape or labels for reconstitution dates
Where to Go Next
- Finish this page. You now have the frame.
- Pick one compound on Single Peptides. BPC-157 is a common first read.
- Read Reconstitution and Deployment Methods.
- Run numbers in the Calculator until the math clicks.
- Keep the Glossary open for unfamiliar terms.
- Check FAQ when something practical comes up.