Peptides from the ground up
If peptides keep showing up on your feed and you are trying to work out what they even are, you are in the right place. This guide starts from zero and needs no science background. We cover what peptides are, how they work in plain words, what all the shorthand means and how people actually handle them, one small step at a time.
What are peptides?
Peptides are short chains of amino acids, the same building blocks that make up proteins. The only real difference is length. Chains of roughly 2 to 50 amino acids are called peptides, and longer chains are proteins. Your body makes thousands of them, and they act as signals, hormones and regulators for all kinds of processes.
A few you already know are peptides: insulin, which manages blood sugar, oxytocin, tied to bonding and growth hormone, which is technically a protein but gets grouped in with the rest. When the research world says peptides, it usually means lab made copies of natural peptides, or new analogs designed to act like them, sold as freeze dried powder for research.
How peptides work
A peptide works by fitting a specific receptor on or inside a cell and setting off a response. Picture a key in a lock. The peptide is the key, the receptor is the lock, and the effect is what happens when the door opens.
Different peptides fit different locks, and that is why their effects vary so much. One might tell your body to release more growth hormone. Another, like semaglutide, works on the signals that control appetite and blood sugar. A repair peptide like BPC-157 nudges the pathways your body uses to heal. Same idea every time, just a different lock.
The thing to hold onto is that each peptide is picky. It has one main target, a dose range where it actually does something and a window of time it stays active before your body clears it. That is why the dose, the timing and how you take it all matter. Get them wrong and the same peptide can do nothing, do something you did not expect or bring on side effects.
The main categories
Peptides are usually grouped by the job they are studied for. These are the groups you will run into most, in plain terms.
Recovery and tissue repair
Studied for healing wounds, repairing tendons and ligaments, settling the gut and calming inflammation. The two you will hear about most are BPC-157, which comes from a protein that protects the stomach, and TB-500, a lab made piece of a natural healing protein. People often run them together.
Growth hormone and secretagogues
A secretagogue is just something that tells your body to make more of its own of something. This group is either growth hormone itself or a gentle nudge that tells your body to release more of its own. The nudges come in two styles that happen to work well as a pair, which is why you often see two combined, like CJC-1295 with ipamorelin. Sermorelin and tesamorelin are other common names here.
Metabolic and weight management
This is the fastest growing group, the one behind the weight-loss headlines. These peptides copy a natural gut hormone called GLP-1, the signal that tells you that you are full and helps manage blood sugar. Semaglutide copies one such signal, tirzepatide copies two and retatrutide copies three, which is the rough reason the newer ones tend to hit harder. They are also among the most heavily studied peptides in medicine today.
Skin, cosmetic and anti-aging
Studied for skin quality, tanning, collagen and the look of aging. Common examples are GHK-Cu, a copper peptide studied for skin repair, and Melanotan, studied for skin pigmentation.
Hormonal and sexual health
Peptides that work on reproductive and sexual pathways. HCG supports testosterone production in clinical use, and PT-141 is an approved treatment for low sexual desire.
Nootropic
Studied for focus, memory and mood. These act on brain signals rather than muscle or fat. Semax and Selank are the names you will see most.
Longevity and anti-aging
Studied for the aging process itself, things like cellular energy, repair and sleep-wake rhythm. NAD+ and epithalon sit here.
How peptides are supplied
Research peptides show up as a freeze dried powder, a small white cake at the bottom of a sealed glass vial with a rubber stopper and a metal cap. The label lists the name and the total amount, like BPC-157 5 mg. It is not ready to use as is. First it has to be reconstituted, or dissolved in a liquid, to make an injectable solution. The powder form exists because peptides last far longer dry than in liquid.
What reconstitution means
Reconstitution is the word for dissolving the dry powder into a liquid. In published research the powder is dissolved by adding bacteriostatic water to the vial, and the amount of water sets the concentration, which is how much peptide sits in each unit of liquid. More water gives a more dilute solution, less water a stronger one. That is the whole idea, and it is worth understanding because it is what the dose math below is built on.
Every compound page lists the water amount that makes the concentration land on round numbers, and the calculator works the concentration out for any amount.
Why bac water, not plain water
The benzyl alcohol in bacteriostatic water holds off bacteria, so a mixed vial stays usable for many doses across roughly 25 to 30 days. Plain sterile water has no preservative, so you would have to use the whole vial within a day or two. For anything multi dose, bac water is the right pick.
Units and measurements
Mixing up units is the number one beginner mistake. Three systems are in play, and they measure different things.
Weight: mg and mcg
These measure how much peptide you have by weight. 1 mg is 1,000 mcg. Some peptides are dosed in milligrams, like semaglutide at 0.25 mg, and others in micrograms, like ipamorelin at 200 mcg. Swap them and you are off by a factor of 1,000.
Volume: mL and syringe units
Volume is how much liquid a dose works out to. On a U-100 insulin syringe the marks run 0 to 100 units, where 100 units is 1 mL, so one unit is 0.01 mL. The key point is that these are volume marks, not dose marks. A unit mark tells you nothing about how much peptide is in that volume until you know the concentration.
Potency: IU
International units measure biological strength for a few standardized compounds, such as HGH at about 3 IU per mg. IU are not the same as syringe units, and the two get confused a lot in online write-ups. IU describe potency, while syringe units describe volume.
Putting it together
Here is how the numbers relate, using a 5 mg vial dissolved in 2 mL of bac water as published protocols often describe. The concentration is 5 mg divided by 2 mL, which is 2.5 mg per mL. For a 250 mcg reference amount, that is 0.25 mg, and 0.25 divided by 2.5 is 0.10 mL, which lines up with the 10 mark on a U-100 syringe. The calculator does the same arithmetic for any vial.
Storage
Before reconstitution, the dry powder keeps best in the fridge at 2 to 8 °C for the long haul. Room temperature is fine for short stretches, but heat and light break peptides down faster, and many can be frozen for extended storage. Keep it out of direct sun and humidity.
After reconstitution, the liquid should always be refrigerated at 2 to 8 °C, and most mixed peptides hold for about 25 to 30 days. Never freeze a reconstituted peptide, since ice crystals can snap the chain. Keep the vial upright, do not shake it, and mark the date you mixed it.
How they are studied
Research describes compounds by the route they were given in the studies rather than as a set of steps to follow. Most are studied subcutaneously, a few such as HCG are studied intramuscularly, and a small number use oral or nasal forms because most peptides survive the gut poorly. Which route a study used is background on the research, not a signal to reproduce it.
Safety
Every compound carries risk. A few principles hold across the board.
Side effects depend on the peptide. There is no single profile for peptides as a group. Common threads include injection site reactions, headaches, nausea and fatigue. GH related peptides can bring water retention, joint pain and shifts in blood sugar. GLP-1 agonists often cause gut effects. Each compound page has its own safety notes.
Dose matters, and more is not better. Peptides have a curve where the effect levels off while side effects keep climbing. Sticking to evidence based ranges, rather than forum megadose talk, is the biggest risk cut you can make.
Source quality is not guaranteed. Research use only material sits outside pharmaceutical oversight. A vendor certificate of analysis is not the same as regulated quality control, so purity, sterility and accurate labeling are not assured. That is a real risk worth understanding.
Legal status varies. Some peptides are prescription drugs, some carry specific federal limits, many sit in a gray area as research chemicals and most performance related ones are banned by WADA for tested athletes. See the FAQ for more.
What the research references involve
For context, studies and reference protocols typically involve the peptide vial itself, bacteriostatic water as the diluent, refrigerator space for both the dry and the mixed vial and simple labeling to track the mix date. This is background on what the research setup looks like, not a shopping list or a prompt to assemble one.
How to use DosingReference
Compound library. A reference page for every compound we cover, with an overview, the dosing ranges reported in research, reconstitution math sized to the vial, storage, what the literature reports and citations. It covers both single peptides and blends.
Calculator. Enter a vial size, a water amount and a target amount, and it returns the concentration, the equivalent volume and how many doses a vial holds. It works for any compound.
FAQ. Quick answers on reconstitution, storage, legality and using the site.
A suggested path
- Finish this guide to get the fundamentals down.
- Pick one compound that fits your interest and read its full page. BPC-157 is a common first stop, since it is widely studied and the handling is simple.
- Use the calculator to practice the math with that vial size and dose until the link between vial content, water, concentration and units clicks.
- Check the FAQ for specific questions on storage, handling and safety.