Plain guide to peptides

A peptide is a short chain of amino acids, the same building blocks that make up the proteins in your body. Many act like little signals that tell your cells to do something: build muscle, calm inflammation, curb appetite, or repair tissue. Some peptides are FDA-approved medicines. Most of the ones people talk about online are not, and that difference matters more than anything else on this page.

There are two very different routes, and they are not the same on safety or legality.

• The prescription route: a licensed clinic or compounding pharmacy, with a prescription. This is the above-board path for the approved and prescribable compounds.
• The research route: research-chemical vendors, a legal gray area where quality is entirely on the seller.

We do not sell peptides, and we do not hand you a list of sellers, because that market changes constantly and a name that looks fine today can be gone or bad tomorrow. What we do instead is teach you how to judge a source for yourself.

Most peptides arrive as a freeze-dried powder in a small vial. Before you can use one, you mix it with a liquid called bacteriostatic water. That mixing step is called reconstitution, and it is where most beginners get lost. Two things make it click:

There is no single correct amount of water. The amount you add decides how concentrated the mix is. More water makes each drop weaker, less water makes it stronger. Neither is wrong. It only changes the number you draw to, not how much peptide you have.

The water amount is a convenience choice. You pick the amount that makes your dose easy to measure. That is really all it is.

1 mL

10 mg/mL

draw 05 units

2 mL

5 mg/mL

draw 10 units

3 mL

3.3 mg/mL

draw 15 units

Our calculator shows the options side by side, the concentration and the syringe draw for each, and labels the one that is easiest to measure. Try the calculator →

How to actually mix it

A few mechanical rules most people agree on: add the water slowly, letting it run down the inside wall of the vial, and do not shake it. Swirl it gently until the powder dissolves, since shaking can damage some peptides.

One real exception is worth knowing. IGF-1 LR3 is usually mixed with a dilute acetic acid solution, not bacteriostatic water. It is the odd one out, so follow that product's own instructions. For almost everything else, bacteriostatic water is the standard.

Reading an insulin syringe

Peptide doses are drawn with an insulin syringe, marked in units. Here is the one fact that unlocks it: 100 units equals 1 mL. Units measure how much liquid you pull into the syringe, not how much peptide is in it. The calculator turns your dose and your water amount into an exact unit mark to draw to, and shows it on a picture of a syringe so you can see it.

35 units = 0.35 mL

100 units = 1 mL on a standard insulin syringe.

Micrograms versus milligrams (the mistake to avoid)

250 mcg = 0.25 mg

This trips up almost everyone. Doses are written in either micrograms (mcg) or milligrams (mg), and 1 mg equals 1,000 mcg. A "250 mcg" dose and a "0.25 mg" dose are the exact same amount. Mixing these two up is the most common and most dangerous beginner mistake, so the calculator lets you pick your unit and does the conversion for you.

One thing we will never do is tell you how much to take. On every page you will see the commonly referenced range and the evidence behind it, and then you enter your own number, the one your clinician gave you, or one you choose to model. We show the math. The decision is yours and your clinician's.

The last piece is simply not running out. Once the tool knows your dose, how often you take it, and how many vials you have, it tells you how many months your supply will last and the date to reorder by. That is the whole point of planning ahead instead of scrambling at the end of a vial.

Reactions are common, and most are minor. The important thing is telling the difference between annoying-but-fine and stop-and-get-help. There are three kinds worth knowing.

Injection-site irritation (most common)

Redness, itching, or a small bump right where the needle went in. It usually comes from the needle or the liquid, not from an allergy, and it fades within a few hours to a day. Rotating where you inject helps.

A mast cell or histamine reaction (looks scary, usually mild)

Your skin is full of immune cells called mast cells. Some peptides poke them directly into releasing histamine, without your immune system deciding the peptide is an enemy. That is what causes the local welt, redness, or itch that looks like a bug bite, or a broader flush across the skin. A few peptides are known for this, CJC-1295 and the GHRP growth-hormone peptides in particular.

Here is the key point: this looks like an allergy, but it is not one. It is a direct chemical reaction, usually mild, and it often settles on its own fairly quickly. A welt or flush is not the same as being allergic. If you choose to keep injecting, go slowly and keep an eye on how your skin responds over the next few doses. This is a different thing from the true allergic reaction below, which is the one to act on right away.

A true allergic reaction (rare, serious)

Here your immune system treats the peptide as a threat, and the warning signs are different from a little redness: hives that spread beyond the injection site, swelling of the face, lips, tongue, or throat, trouble breathing, dizziness, or a racing heart. This one is a medical emergency.

What to do

• Stop using it. If a peptide causes anything more than brief, minor site redness, stop and do not re-dose it without talking to a clinician first.
• For mild itching or redness, a cold compress helps, and a pharmacist can point you to an over-the-counter antihistamine if it is truly minor.
• For any severe sign, the breathing, swelling, or spreading hives above, get emergency help immediately.
• Tell your clinician about any reaction, even one that settled on its own. It changes what is safe for you going forward.

This is one of the clearest reasons the rest of this guide matters. Start low, go slow, watch your body, and keep someone medical in the loop, so that if a reaction does happen you catch it early and handle it right.

Peptides feel confusing because nobody explains the mechanics plainly and honestly. That is what this whole site is for. Understand what a thing is, calculate your mix and your draw, see what it really costs, and plan your supply. What we will not do is pick your dose or your seller. Those are yours to decide, ideally with a clinician in the loop.