Carl’s got you.What is a peptide, really?
A peptide is a short chain of amino acids — the same building blocks that make proteins, just smaller. Your body already runs on hundreds of them as tiny messengers: “heal this,” “release that hormone,” “you’re full now.” Research peptides are lab-made copies of those messengers, studied to see what happens when you add more of a specific signal.
Where a drug is often a foreign chemical, most peptides are copies of something your body already recognises — which is a big part of the appeal, and why the research is so interesting.
How they’re made and sold
Peptides are synthesised in a lab, then freeze-dried (lyophilised) into a fine powder and sealed in a small glass vial. Almost everything in this guide is sold “for research use only” — because most peptides are not approved for human use (the GLP-1 fat-loss drugs are the notable exception). That label isn’t a marketing quirk; it’s the legal reality in most regions.
The units you’ll keep seeing
This trips up almost every beginner, so lock it in now:
| Unit | What it means |
|---|---|
| mg | Milligram. Vials are usually labelled in mg (e.g. 5mg, 10mg). |
| mcg | Microgram. 1 mg = 1,000 mcg. Doses are often in mcg. |
| IU | International unit — used for some hormones; converts differently per substance. |
| mL | Millilitre — the volume of liquid, e.g. of bacteriostatic water. |
Need to flip between them? Carl’s Dose Converter does it instantly.
“Reconstitution” — the one skill you need
Because peptides arrive as a dry powder, you can’t measure a dose until you’ve reconstituted it — added liquid so it becomes a solution you can draw into a syringe. The standard liquid is bacteriostatic water (BAC): sterile water with a tiny amount of preservative so the vial stays usable for weeks in the fridge.
The maths — “how much water, so that my dose is X units on the syringe” — is where beginners slip. Don’t guess:
→ Use Carl’s Reconstitution Calculator (it also tells you how long the vial will last).
How they’re taken
- Subcutaneous (subQ) — a tiny injection into the fat just under the skin, with an insulin syringe. The most common route.
- Intramuscular (IM) — deeper, into muscle; used for some compounds.
- Oral / capsule — for the few that survive the stomach (e.g. BPC-157 for gut goals).
- Intranasal — nasal sprays, common for the brain peptides (Selank, Semax).
- Topical — creams/serums, e.g. GHK-Cu for skin.
Carl’s five rules for starting smart
- Read before you buy. Understand the mechanism and the evidence first — that’s literally what this directory is for.
- Proof over promises. A real Certificate of Analysis (COA) beats a slick label. No batch report? Be suspicious. (More in the Legal & Safety guide.)
- Measure twice. Reconstitution maths is the #1 rookie error. Calculator, then double-check.
- Start low, go slow. Lower doses, one variable at a time. You can always add; you can’t un-inject.
- Talk to a clinician. None of this replaces medical advice. A real doctor beats a forum thread.
