How to Reconstitute and Inject Peptides: The Complete Beginner's Guide

Introduction: Why This Guide Exists

If you have recently purchased a peptide in lyophilized (freeze-dried) form and are staring at a vial of white powder wondering what to do next, you are not alone. Reconstitution and injection are the two biggest practical barriers for peptide newcomers, and yet the process is straightforward once you understand the fundamentals.

This guide walks through every step from opening the vial to proper storage, with enough detail that a complete beginner can follow along confidently. We also cover the math behind dosing calculations, because measuring peptides accurately is not optional—it is essential for both safety and effectiveness.

For step-by-step guides on specific aspects of this process, see our dedicated articles on How to Reconstitute Peptides, How to Inject Peptides, and How to Store Peptides. For the reconstitution math, our Peptide Calculator and Bacteriostatic Water Calculator automate the calculations described in this article. If you are still deciding whether peptides are right for you, start with our Are Peptides Safe? overview.

What You Need: Complete Supply List

Before you begin, gather all necessary supplies. Having everything ready before you start ensures a clean, uninterrupted process.

The Peptide Vial. Your peptide arrives as a lyophilized (freeze-dried) powder in a sealed glass vial, typically with a rubber stopper and an aluminum crimp cap. Common vial sizes contain 2 mg, 5 mg, or 10 mg of peptide. The exact amount is listed on the vial label or certificate of analysis. Keep the vial refrigerated until you are ready to reconstitute.

Bacteriostatic Water (BAC Water). This is sterile water containing 0.9 percent benzyl alcohol as a preservative. The benzyl alcohol inhibits bacterial growth, which is critical because you will be drawing multiple doses from the same vial over days or weeks. Do not substitute sterile water (which has no preservative) unless you plan to use the entire vial in one session. BAC water is available from medical supply companies and should be stored at room temperature.

Syringes: Two Types. You need two types of syringes for this process:

• Mixing syringe (1 mL or 3 mL): A standard syringe with a 21 to 25 gauge needle, used to draw BAC water and add it to the peptide vial. The larger gauge makes drawing water easier.
• Insulin syringe (0.5 mL or 1 mL): A 29 to 31 gauge insulin syringe with a short, thin needle (typically 0.5 inch), used for subcutaneous injection. These are measured in "units"—a 1 mL insulin syringe has 100 units. The thin needle makes injections nearly painless.

Alcohol Swabs. Isopropyl alcohol prep pads for sterilizing vial tops, BAC water bottle stoppers, and injection sites. These are inexpensive and essential for preventing contamination.

Sharps Container. A puncture-resistant container for disposing of used needles safely. Never throw needles in regular trash. Many pharmacies offer free sharps containers and disposal services.

Reconstitution: Step-by-Step

Reconstitution is the process of dissolving the freeze-dried peptide powder in bacteriostatic water to create an injectable solution. This is the most important step to get right, because it determines the concentration of your solution and therefore the accuracy of every subsequent dose.

Step 1: Clean Your Workspace. Work on a clean, flat surface. Wash your hands thoroughly with soap and water. Lay out all supplies. A clean kitchen counter or desk works fine—you do not need a sterile laboratory environment, but basic cleanliness is non-negotiable.

Step 2: Determine How Much BAC Water to Add. This is where the math matters. The amount of BAC water you add determines the concentration of your solution. There is no single "correct" amount—you choose a volume that makes dosing convenient with your insulin syringe.

A common approach: for a 5 mg vial, adding 2 mL (200 units on an insulin syringe) of BAC water creates a concentration where each 10 units on your insulin syringe equals 250 mcg of peptide. For a 10 mg vial, adding 2 mL creates a concentration where each 10 units equals 500 mcg.

The formula is simple: Concentration per unit = Total peptide (mcg) / Total BAC water (units). If you have a 5,000 mcg (5 mg) vial and add 200 units (2 mL) of BAC water, each unit on your syringe delivers 25 mcg of peptide. To get a 250 mcg dose, you would draw 10 units.

Our Peptide Calculator automates this math. Enter your vial size, the amount of BAC water you plan to add, and your desired dose, and it calculates exactly how many units to draw. The BAC Water Calculator helps you determine the optimal amount of BAC water to add based on your desired concentration.

Step 3: Swab the Vial Tops. Use an alcohol swab to clean the rubber stopper of both the peptide vial and the BAC water container. Let the alcohol dry for 5 to 10 seconds before piercing the stopper. This kills surface bacteria that could contaminate your solution.

Step 4: Draw the BAC Water. Using your mixing syringe (the larger one), draw the calculated amount of BAC water from the container. Pull back the plunger slowly to avoid air bubbles. If you get bubbles, tap the syringe gently and push them back out before removing the needle from the BAC water container.

Step 5: Add BAC Water to the Peptide Vial. Insert the mixing syringe needle through the rubber stopper of the peptide vial, angling the needle so the water runs down the inside wall of the vial. Do not inject the water directly onto the powder. This is critical—peptides are delicate molecules, and the force of water hitting the powder directly can damage them. Let the water flow gently down the glass wall and onto the powder.

Step 6: Let It Dissolve. Do not shake the vial. Set it down and wait. Most peptides dissolve within 1 to 5 minutes with only gentle swirling if needed. You can tilt the vial gently from side to side, but vigorous shaking can denature the peptide (break its three-dimensional structure and destroy its biological activity). The solution should become clear and colorless. If it remains cloudy or has particles after 10 minutes of gentle swirling, there may be a quality issue with the peptide.

Step 7: Label the Vial. Write the date of reconstitution, the peptide name, and the concentration (e.g., "BPC-157, 250 mcg per 10 units, reconstituted 2/24/2026") on the vial or a label attached to it. This prevents confusion, especially if you are using multiple peptides.

Dosing Math: Getting It Right

Accurate dosing is essential. Too little peptide may be ineffective; too much wastes product and may increase side effects. Understanding the math ensures precision.

The Core Formula:

Units to draw = (Desired dose in mcg / Total peptide in mcg) x Total BAC water in units

Example 1: BPC-157. You have a 5 mg (5,000 mcg) vial reconstituted with 2 mL (200 units) of BAC water. You want a 250 mcg dose. Units to draw = (250 / 5,000) x 200 = 10 units. Draw 10 units on your insulin syringe.

Example 2: CJC-1295. You have a 2 mg (2,000 mcg) vial reconstituted with 1 mL (100 units) of BAC water. You want a 100 mcg dose. Units to draw = (100 / 2,000) x 100 = 5 units. Draw 5 units on your insulin syringe.

Example 3: Ipamorelin. You have a 5 mg (5,000 mcg) vial reconstituted with 2.5 mL (250 units) of BAC water. You want a 200 mcg dose. Units to draw = (200 / 5,000) x 250 = 10 units. Draw 10 units on your insulin syringe.

If the math produces awkward numbers (like 7.3 units), adjust the amount of BAC water you add during reconstitution to create rounder numbers. The Peptide Calculator helps you find the optimal BAC water volume for convenient dosing.

Injection Technique: Subcutaneous Injection

Most peptides are administered via subcutaneous (sub-Q) injection—injecting into the fat layer just beneath the skin. This is the same technique used for insulin, and it is simple, relatively painless with proper technique, and does not require hitting a muscle or vein.

Step 1: Draw Your Dose. Using a clean insulin syringe, insert the needle through the rubber stopper of your reconstituted peptide vial. Turn the vial upside down so the needle tip is submerged in the solution. Pull back the plunger slowly to the mark that corresponds to your calculated dose. If you see air bubbles, tap the syringe barrel gently to move them to the top, then push the plunger slightly to expel the air.

Step 2: Choose Your Injection Site. The most common subcutaneous injection sites are:

• Abdomen: The area around the belly button (avoiding a 2-inch radius around the navel itself). This is the most popular site due to easy access and consistent absorption. Pinch a fold of skin and inject into the fold.
• Thigh: The front or outer side of the mid-thigh. Another easy-access site with plenty of subcutaneous tissue.
• Upper arm: The fatty area on the back of the upper arm. Slightly more difficult to self-inject but useful for rotation.
• Love handles: The area of subcutaneous fat on the sides of the lower torso. Useful as an additional rotation site.

Note on site-specific injections: Some peptides, particularly BPC-157, are sometimes injected near the site of injury (e.g., near an injured shoulder or knee) with the reasoning that local delivery may enhance the compound's effects at the target tissue. Other peptides like Ipamorelin and CJC-1295 are systemic and can be injected at any standard subcutaneous site.

Step 3: Clean the Injection Site. Swab the chosen injection site with an alcohol prep pad. Let the alcohol dry completely (5 to 10 seconds). Injecting through wet alcohol stings unnecessarily.

Step 4: Inject. Pinch a fold of skin at the injection site between your thumb and forefinger. Insert the needle at a 45 to 90 degree angle (90 degrees is straight in; 45 degrees for very lean individuals with less subcutaneous fat). Push the plunger slowly and steadily. There is no rush. Once the plunger is fully depressed, wait 5 to 10 seconds before withdrawing the needle to ensure the full dose is delivered.

Step 5: Withdraw and Dispose. Pull the needle out at the same angle you inserted it. If there is a small drop of blood or liquid at the injection site, press gently with a clean cotton ball or alcohol swab. Do not rub the site. Dispose of the used syringe in your sharps container immediately. Never recap a used needle.

Rotation. Rotate injection sites systematically. Do not inject in the same spot repeatedly. Repeated injection at the same site can cause lipohypertrophy (localized fat buildup), irritation, and scarring. A simple rotation pattern (e.g., left abdomen, right abdomen, left thigh, right thigh) ensures each site has time to recover between uses.

Storage: Keeping Your Peptides Viable

Proper storage is critical for maintaining peptide potency. Peptides are biological molecules that degrade under adverse conditions. For a comprehensive storage guide, see our How to Store Peptides article.

Unreconstituted (Lyophilized) Peptides. Store in the refrigerator (36 to 46 degrees Fahrenheit / 2 to 8 degrees Celsius). Lyophilized peptides are relatively stable and can maintain potency for months to years when refrigerated. For long-term storage (more than 6 months), freezing at -20 degrees Celsius is ideal. Keep vials away from light, which can degrade certain peptides.

Reconstituted Peptides. Once reconstituted with BAC water, store the vial in the refrigerator. Reconstituted peptides have a limited shelf life—typically 4 to 6 weeks for most peptides when stored properly in the refrigerator. The benzyl alcohol preservative in BAC water helps prevent bacterial growth, but it does not stop peptide degradation indefinitely. Mark the reconstitution date on each vial and discard any vial that is past its recommended use period.

Temperature Sensitivity. Never freeze reconstituted peptides. The ice crystal formation can damage the peptide structure. Similarly, do not leave reconstituted peptides at room temperature for extended periods—brief exposure during dose preparation is fine, but the vial should return to the refrigerator promptly after each use.

Light Sensitivity. Some peptides are photosensitive (degraded by light). When in doubt, keep vials in their original box or wrap them in aluminum foil. Store them in a dedicated section of your refrigerator where they will not be exposed to light each time the door is opened.

Travel Considerations. If traveling with peptides, use an insulated cooler bag with ice packs to maintain refrigeration. TSA allows medically necessary injectable medications and syringes through security (though you may want to carry documentation). Lyophilized peptides are more travel-friendly than reconstituted ones because they are more temperature-stable.

Common Mistakes and How to Avoid Them

Even experienced users make mistakes. Here are the most common errors and how to prevent them:

Mistake 1: Spraying BAC Water Directly onto the Powder. This is the most common reconstitution error. Forcefully squirting water onto the lyophilized powder can damage the peptide's three-dimensional structure. Always aim the stream down the inside wall of the vial and let the water gently flow onto the powder.

Mistake 2: Shaking the Vial. Vigorous shaking creates foam and can denature the peptide through mechanical stress. If the powder does not dissolve immediately, set the vial down and wait, or roll it gently between your palms. Patience preserves potency.

Mistake 3: Using Sterile Water Instead of BAC Water. Sterile water has no preservative. If you use sterile water and draw multiple doses over several days, bacteria can grow in the solution. BAC water's benzyl alcohol prevents this. Only use sterile water if you plan to use the entire vial in a single session or within 24 hours.

Mistake 4: Incorrect Dosing Math. Getting the reconstitution math wrong means every dose is wrong. Double-check your calculations or use our Peptide Calculator to verify. A common error is confusing milligrams with micrograms (1 mg = 1,000 mcg). Another is confusing milliliters with units on an insulin syringe (1 mL = 100 units).

Mistake 5: Not Rotating Injection Sites. Repeatedly injecting in the same spot leads to tissue damage over time. Establish a rotation pattern from the start and stick to it. Some people keep a simple log noting which site they used each day.

Mistake 6: Injecting Into Cold Skin. Injecting while the injection site is still wet with cold alcohol increases discomfort. Wait for the alcohol to dry completely. Some people also warm the peptide solution to body temperature by holding the syringe in their hand for 30 seconds before injecting, which can reduce injection-site discomfort.

Mistake 7: Improper Storage. Leaving reconstituted peptides at room temperature, freezing them, or exposing them to light degrades the compound and wastes money. Refrigerate immediately after each use. Our How to Store Peptides guide covers the specifics for different compound types.

Mistake 8: Reusing Needles. Every injection should use a fresh, sterile needle. Reusing needles introduces bacteria, dulls the needle (making injections more painful and causing more tissue damage), and increases infection risk. Insulin syringes are inexpensive—use a new one every time.

Hygiene and Safety Best Practices

Injection involves breaking the skin barrier, which creates a potential entry point for bacteria. Following basic hygiene protocols minimizes infection risk to near zero.

Always Wash Hands. Before handling any supplies, wash your hands thoroughly with soap and water for at least 20 seconds. This alone eliminates the majority of contamination risk.

Always Swab Vial Tops and Injection Sites. Alcohol swabs before piercing a vial stopper and before injecting are mandatory steps. They take seconds and prevent contamination.

Never Share Needles or Vials. This should be obvious, but it bears stating explicitly. Never use another person's syringe or allow anyone else to draw from your reconstituted peptide vial. Cross-contamination and bloodborne pathogen transmission are serious risks.

Dispose of Sharps Properly. Used needles go in a sharps container, period. When the container is full, take it to a pharmacy, hospital, or designated disposal site. Many communities have mail-back sharps disposal programs. Never throw loose needles in household trash—this endangers waste workers and others.

Watch for Signs of Infection. After injection, monitor the site for the first 24 to 48 hours. Mild redness and slight warmth immediately after injection are normal and resolve quickly. Signs of infection include increasing redness, swelling, warmth, pain, or pus formation that develops or worsens over hours to days. If you suspect an injection-site infection, seek medical attention promptly.

For a broader overview of peptide safety, side effects, and when to seek medical attention, visit our Are Peptides Safe? and Peptide Side Effects guides.

The Bottom Line

Reconstituting and injecting peptides is a learnable skill that becomes routine after a few sessions. The process boils down to: add the right amount of BAC water to the vial gently, do the math to determine how many units to draw for your dose, clean everything with alcohol, inject subcutaneously, and store the vial in the refrigerator.

The most important things to get right are the dosing math (use our Peptide Calculator), the gentle handling during reconstitution (never shake, never spray directly onto powder), and basic hygiene (clean hands, alcohol swabs, fresh needles, proper disposal).

If you are new to peptides entirely, take the time to understand the compound you are using before focusing on the preparation and injection process. Read our What Are Peptides? overview, the specific compound guide for your peptide, and the relevant goal page for your research objective. Knowing what you are using and why is just as important as knowing how to prepare and administer it.

For additional resources, our How to Reconstitute Peptides, How to Inject Peptides, and How to Store Peptides guides provide focused, step-by-step instructions for each phase of the process.