If you’ve landed here, you’re probably seeing peptides mentioned everywhere — on forums, in wellness content, in fitness circles — and trying to figure out what they actually are, how they work, and what all the jargon means. This guide is the starting point. It covers everything from basic biology to practical handling, without assuming any prior knowledge.
Important: All information on PeptideDosages.com is for research and educational purposes only. Nothing here constitutes medical advice. Consult a qualified healthcare professional before making any decisions involving peptides or any other compounds.
What Are Peptides?
Peptides are short chains of amino acids — the same building blocks that make up proteins. The difference is length: peptides are generally defined as chains of 2 to 50 amino acids, while longer chains are classified as proteins. Your body produces thousands of peptides naturally, and they serve as signaling molecules, hormones, and regulators of biological processes.
Some examples you may already know without realizing they’re peptides: insulin (51 amino acids, regulates blood sugar), oxytocin (9 amino acids, involved in social bonding), and growth hormone (191 amino acids, technically a protein but widely discussed in the peptide community).
When people in the research community talk about “peptides,” they’re usually referring to synthetic versions of naturally occurring peptides (or novel analogues designed to mimic them) that are produced in a lab and sold as lyophilized (freeze-dried) powders for research purposes.
How Do Peptides Work?
Peptides work by binding to specific receptors on or inside cells, triggering a biological response. Think of it like a key fitting into a lock — the peptide is the key, the receptor is the lock, and the biological effect is what happens when the door opens.
Different peptides target different receptors, which is why they have such varied effects. A growth hormone releasing peptide (like GHRP-6) binds to ghrelin receptors in the pituitary, triggering GH release. A GLP-1 agonist (like semaglutide) binds to GLP-1 receptors in the pancreas and brain, affecting insulin secretion and appetite. BPC-157 interacts with multiple pathways related to tissue repair and inflammation.
The key concept to understand is specificity: each peptide has a specific target (or set of targets), a specific dose range where it’s active, and a specific half-life that determines how long it stays active in the body. This is why dosage protocols matter — the same peptide at the wrong dose, wrong frequency, or wrong route of administration may produce no effect, a different effect, or unwanted side effects.
Major Peptide Categories
Peptides researched today span a wide range of biological targets. Here are the major categories you’ll encounter:
Recovery & Tissue Repair
These peptides are studied for their potential roles in wound healing, tendon and ligament repair, gut healing, and reducing inflammation. The two most commonly discussed are BPC-157 (Body Protection Compound-157, a 15-amino acid peptide derived from gastric protective proteins) and TB-500 (a synthetic fragment of Thymosin Beta-4, involved in cell migration and tissue repair). They are frequently used together in both blends and stacks.
Growth Hormone & Secretagogues
This category includes peptides that either are growth hormone (like HGH 191AA / somatropin) or stimulate your body to release more of its own GH. The stimulators fall into two sub-groups:
- GHRH analogues (amplify GH release pulses): CJC-1295 (with and without DAC), Sermorelin, Tesamorelin
- GHRPs / Ghrelin mimetics (trigger GH release through the ghrelin receptor): GHRP-2, GHRP-6, Ipamorelin, Hexarelin, MK-677 (oral, non-peptide)
GHRH analogues and GHRPs are often combined (e.g., CJC-1295 + Ipamorelin blends) because they work through complementary pathways and can produce synergistic GH release. Browse our single peptide protocols for individual dosing details.
Metabolic & Weight Management
GLP-1 receptor agonists are the fastest-growing peptide category. These compounds mimic the incretin hormone GLP-1 to regulate appetite, blood sugar, and body weight. Key names include semaglutide (the active ingredient in Ozempic/Wegovy), tirzepatide (dual GIP/GLP-1 agonist, the active ingredient in Mounjaro/Zepbound), and retatrutide (triple agonist targeting GLP-1, GIP, and glucagon receptors). These are among the most heavily researched peptides in clinical medicine today.
Skin, Cosmetic & Anti-Aging
Peptides in this category are researched for skin quality, pigmentation, collagen synthesis, and anti-aging applications. Examples include GHK-Cu (copper peptide studied for skin remodeling and wound healing), Melanotan II (melanocortin receptor agonist studied for skin pigmentation), and various collagen-stimulating peptides.
Hormonal & Sexual Health
This includes peptides that interact with reproductive and sexual health pathways. HCG (human chorionic gonadotropin) is used clinically to support testosterone production. PT-141 (bremelanotide) is an FDA-approved melanocortin agonist for hypoactive sexual desire disorder. Kisspeptin-10 is researched for its role in GnRH signaling and reproductive function.
How Peptides Are Supplied
Research peptides arrive as a lyophilized powder — a white or off-white cake or powder sitting at the bottom of a small glass vial. The vial is sealed with a rubber stopper and an aluminum crimp cap. The label tells you the peptide name and the total amount in the vial (e.g., “BPC-157 5mg” or “Semaglutide 3mg”).
This powder is not ready to use as-is. It must first be reconstituted — dissolved in a liquid diluent — to create an injectable solution. The powder form exists because peptides are far more stable as a dry powder than in liquid, giving them a much longer shelf life before reconstitution.
Reconstitution: Turning Powder into Solution
Reconstitution is the single most important practical skill in peptide handling. Here’s how it works:
What you need
- The peptide vial (lyophilized powder)
- Bacteriostatic water (BAC water) — sterile water with 0.9% benzyl alcohol as a preservative
- An insulin syringe — typically a U-100, 1 mL syringe
- Alcohol swabs — to sterilize the vial stopper before each puncture
The process (simplified)
- Clean the rubber stopper of the peptide vial and the BAC water vial with an alcohol swab.
- Draw the desired amount of BAC water into the syringe. The amount you add determines the concentration (more water = more dilute = more liquid per dose).
- Inject slowly into the peptide vial, aiming the stream against the glass wall — not directly onto the powder.
- Swirl gently — never shake. Let the powder dissolve. Most peptides dissolve within 1–2 minutes. Some may take up to 10 minutes.
- Refrigerate the reconstituted vial immediately. It’s now ready to use.
Each of our dosage protocol pages specifies the exact amount of BAC water to use for that peptide and vial size, chosen to create a concentration that makes the dose math straightforward. You can also use our Dosage Calculator to compute the exact injection volume for any BAC water amount.
Why BAC water and not regular water?
The benzyl alcohol in bacteriostatic water prevents bacterial growth, allowing you to use the reconstituted vial for multiple doses over 25–30 days. If you used plain sterile water (no preservative), you’d need to use the entire vial within 24–48 hours. For multi-dose vials, BAC water is always the right choice.
Understanding Units & Measurements
Unit confusion is the #1 source of dosing errors for beginners. There are three measurement systems in play, and they measure different things:
Weight: mg and mcg
mg (milligrams) and mcg (micrograms) measure how much peptide you’re working with by weight. The relationship is simple: 1 mg = 1,000 mcg. This matters because some peptides are dosed in milligrams (e.g., semaglutide at 0.25 mg) and others in micrograms (e.g., Ipamorelin at 200 mcg). Confusing the two creates a 1,000-fold error.
Volume: mL and syringe “units”
mL (milliliters) measure how much liquid you’re drawing into the syringe. On a standard U-100 insulin syringe, the markings go from 0 to 100 “units,” where 100 units = 1 mL. So each “unit” on the syringe is actually 0.01 mL of liquid. These are volume marks, not dose marks — they tell you nothing about how much peptide is in that volume until you know the concentration.
Potency: IU (International Units)
IU (International Units) measure biological potency for specific peptides — primarily HGH (≈3 IU per 1 mg) and HCG (where IU are defined by bioassay). IU are not the same as syringe “units.” When a protocol says “inject 2 IU of HGH,” it’s specifying potency, not a syringe marking. You still need to calculate the volume based on your reconstitution concentration.
Putting it all together
Here’s a concrete example: You have a 5 mg vial of BPC-157. You add 2 mL of BAC water. The concentration is now 5 mg ÷ 2 mL = 2.5 mg/mL. Your protocol calls for a 250 mcg dose (which is 0.25 mg). So you need: 0.25 mg ÷ 2.5 mg/mL = 0.10 mL, which is 10 units on a U-100 syringe.
If this math feels intimidating, our Dosage Calculator does it for you — enter the vial size, BAC water amount, and target dose, and it outputs the exact syringe volume.
Syringes: Types & How to Read Them
Almost all peptide protocols use insulin syringes because they’re designed for small, precise volumes and have thin needles suitable for subcutaneous injection. There are three common types:
- U-100 (1 mL) — 100 units = 1 mL. The most common syringe for peptides. Each unit = 0.01 mL. Good for doses requiring 5–100 units of liquid.
- U-100 (0.5 mL) — Same scale (100 units per mL) but only holds 0.5 mL (50 units). Easier to read for small-volume doses because the markings are more spread out.
- U-50 / U-20 — Less common. U-50 has 50 units per 0.5 mL, U-20 has 20 units per 0.2 mL. These provide finer graduation for very small doses. Our protocol pages specify which syringe type to use when these are relevant.
Our protocol pages include syringe fill-line diagrams that show exactly where to draw to on your specific syringe type for each dose.
Storage: Before & After Reconstitution
Before reconstitution (lyophilized powder)
- Ideal: Refrigerate at 2–8°C (36–46°F). Most peptides remain stable for months to years in this state.
- Acceptable: Room temperature for short periods (weeks), but heat and light degrade peptides faster.
- Long-term: Some peptides can be frozen for extended storage. Lyophilized powder handles freezing well.
- Avoid: Direct sunlight, heat above 25°C (77°F), and humid environments.
After reconstitution (liquid solution)
- Always refrigerate at 2–8°C (36–46°F). Most reconstituted peptides are stable for 25–30 days.
- Never freeze a reconstituted peptide — ice crystals can break the peptide chain and destroy potency.
- Keep upright in the refrigerator. Don’t shake the vial.
- Note the date you reconstituted. Mark the vial with a piece of tape.
For a deeper dive, see our FAQ section on storage.
Routes of Administration
The vast majority of peptide research protocols use one injection route:
Subcutaneous (SubQ) injection
This means injecting into the fatty tissue layer just beneath the skin. Common sites are the lower abdomen (pinching a fold of skin), the front or outer thigh, and the upper arm. SubQ is the default for most peptides because it provides reliable absorption, is simple to perform, and requires only short, thin-gauge insulin needles.
Intramuscular (IM) injection
Some peptides (like HCG and certain GH protocols) may specify IM injection — directly into muscle tissue. This requires a slightly longer needle and different injection technique. IM injection generally results in faster absorption than SubQ.
Oral and nasal routes
Most peptides have very poor oral bioavailability because stomach acid and digestive enzymes break them down before they reach the bloodstream. There are a few exceptions — oral semaglutide (Rybelsus) uses a special absorption enhancer, and MK-677 (ibutamoren) is an orally active non-peptide GH secretagogue. Some peptides like BPC-157 are also studied via oral administration in research contexts. Nasal administration is researched for certain peptides but is less common in standard protocols.
Safety Considerations
Every peptide carries potential risks. These are some of the general safety principles that apply across the board:
Side effects vary by peptide
There is no universal side effect profile for “peptides” as a class — each compound has its own risk profile based on its mechanism of action. However, some common themes include injection site reactions (redness, swelling, itching), headaches, nausea, and fatigue. GH-related peptides may cause water retention, joint pain, tingling, and changes in glucose tolerance. GLP-1 agonists commonly cause gastrointestinal effects (nausea, constipation, reduced appetite). Each of our protocol pages includes a peptide-specific safety section.
Dose matters
More is not better. Peptides have dose-response curves where effectiveness plateaus and side effects increase. Following evidence-based dosing ranges — rather than forum hearsay about “megadosing” — is the most important risk-reduction step.
Source quality is not guaranteed
Research peptides sold as “for research use only” are not subject to pharmaceutical manufacturing oversight. A Certificate of Analysis (COA) from a vendor does not equal FDA-regulated quality control. Purity, sterility, and accurate labeling are not guaranteed outside the regulated pharmacy system. This is a meaningful risk that informed researchers should understand.
Some peptides have specific legal restrictions
Not all peptides exist in the same legal category. Some (like semaglutide and HGH) are prescription drugs. Others have specific federal restrictions on distribution for human use. Many are classified as “research chemicals” in a legal gray area. And nearly all performance-related peptides are prohibited by WADA for athletes in tested sports. See our FAQ for more details on legality.
Essential Supplies Checklist
If you’re setting up for peptide research for the first time, here’s what you’ll need:
- Peptide vial(s) — lyophilized powder, stored in refrigerator
- Bacteriostatic water (BAC water) — typically a 10 mL or 30 mL vial
- Insulin syringes — U-100, 1 mL or 0.5 mL, with 29–31 gauge needles (most protocols use 29G or 30G)
- Alcohol swabs — for sterilizing vial stoppers and injection sites
- Sharps container — for safe disposal of used needles
- Refrigerator space — for storing both unreconstituted and reconstituted vials
- Optional: Small adhesive labels or tape for marking reconstitution dates on vials
How to Use PeptideDosages.com
Now that you understand the basics, here’s how our site is organized to help you:
Single Peptide Protocols
Individual dosage protocol pages for 90+ peptides. Each page includes a protocol overview (what the peptide is and what it’s researched for), a dosing schedule, reconstitution instructions with the exact BAC water volume for that vial size, syringe fill-line diagrams, supplies lists, safety notes, and citations to source literature.
Peptide Blend Protocols
Protocols for pre-mixed multi-peptide vials — two or more peptides combined in a single vial. These cover the unique reconstitution and dosing math for blends where you need to account for multiple active ingredients in one solution.
Peptide Stack Protocols
Coordinated dosing schedules for using multiple separate peptide vials together. Stack protocols explain the rationale for the combination, the individual dosing for each component, and timing considerations.
Dosage Calculator
Enter any vial size, any BAC water volume, and any target dose — the calculator outputs the exact syringe volume and total number of doses per vial. Works for any peptide.
Blog
In-depth articles covering peptide science, mechanisms of action, clinical evidence, comparisons, and emerging research. Every article is cited with links to source literature.
Glossary & FAQ
Quick-reference resources for terminology and common questions. The glossary covers 35+ terms; the FAQ addresses 20 of the most frequent questions about peptides, reconstitution, storage, legality, and using our site.
Recommended Learning Path
If you’re starting from zero, here’s the order I’d suggest:
- You’re here — finish this guide to understand the fundamentals.
- Pick one peptide that matches your research interest and read its full protocol page. BPC-157 is a common starting point because it’s among the most widely studied and the protocols are straightforward.
- Use the Dosage Calculator to practice the math with that peptide’s vial size and dose. Make sure you understand the relationship between vial content, BAC water volume, concentration, and syringe units.
- Read the Glossary if you hit any terms you don’t recognize.
- Check the FAQ for answers to specific practical questions about storage, handling, and safety.
- Browse the Blog for deeper dives into specific peptides, mechanisms, and current research.
Educational disclaimer: This guide is for research and educational purposes only. It is not medical advice, diagnosis, or treatment guidance. Peptides intended for human therapeutic use require a prescription and physician oversight. Always consult qualified healthcare professionals for medical decisions.