How to Reconstitute Peptides: A Complete Beginner's Guide

If you've just received your first vial of lyophilized peptide powder, you're probably staring at it wondering what to do next. Reconstitution — the process of mixing your peptide powder with bacteriostatic water to create an injectable solution — is straightforward once you understand the basics, but getting it wrong can waste an expensive vial or compromise your results.

This guide walks you through everything: what you need, how to do it step by step, how to calculate your dose, and the mistakes that trip up beginners. Whether you're working with BPC-157, TB-500, semaglutide, or any other research peptide, the process is essentially the same.

What You Need Before You Start

Before reconstituting, gather everything so you're not scrambling mid-process:

• •Lyophilized peptide vial. This is your peptide in freeze-dried powder form. Check the label for the total amount in milligrams (e.g., 5mg BPC-157).
• •Bacteriostatic water (BAC water). This is sterile water with 0.9% benzyl alcohol as a preservative. It's what keeps your reconstituted peptide safe for multi-use over days or weeks. Do not use regular sterile water for injection unless you plan to use the entire vial immediately — it has no preservative.
• •Insulin syringes. 1mL (100 unit) insulin syringes with 29-31 gauge needles are standard for subcutaneous peptide injection. You'll use one to add water and separate ones for dosing.
• •Alcohol swabs. For cleaning vial tops before piercing. Non-negotiable for sterility.

Understanding BAC Water

Bacteriostatic water deserves its own section because it's the most common point of confusion for beginners.

BAC water vs. sterile water: Both are sterile, but BAC water contains 0.9% benzyl alcohol which prevents bacterial growth. This means a reconstituted vial stays safe for repeated use over 28 days (the standard guideline). Sterile water for injection has no preservative — once you add it to a vial, bacteria can grow with each needle insertion, so it should be used within 24 hours.

Where to buy BAC water: It's available from medical supply companies, some pharmacies, and online retailers. A 30mL vial typically costs $5–15 and will reconstitute multiple peptide vials. Make sure you're buying from a reputable source — you're injecting this.

Storage: Unopened BAC water can be stored at room temperature. Once opened, keep it in the fridge and use within 28 days. Write the date you opened it on the vial.

Step-by-Step Reconstitution Process

Here's the actual process. It takes about 2 minutes once you've done it a few times.

Calculating Your Dose

This is where most beginners get confused, but the math is simple once you see the pattern.

The formula:

Example: You have a 5mg (5,000mcg) vial of BPC-157 and add 2mL of BAC water.

• →Concentration: 5,000mcg ÷ 2mL = 2,500mcg per mL
• →For a 250mcg dose: 250 ÷ 2,500 = 0.10mL = 10 units on an insulin syringe
• →For a 500mcg dose: 500 ÷ 2,500 = 0.20mL = 20 units

Insulin syringe units: A standard 1mL insulin syringe has 100 units. So 0.10mL = 10 units, 0.25mL = 25 units, etc. The tick marks on the syringe correspond to units.

Don't want to do the math every time? Use our reconstitution calculator — plug in your vial size, water amount, and desired dose, and it shows you exactly how many units to draw, plus a visual syringe diagram.

How Much BAC Water Should You Add?

There's no single "correct" amount — it depends on your dose and preference. Here's the tradeoff:

• •Less water (1mL) = more concentrated solution. Each unit on your syringe delivers more peptide. Good for higher doses, but small measurement errors have a bigger impact.
• •More water (2–3mL) = more dilute solution. Easier to measure small doses precisely. Better for peptides where you're dosing in the 100–300mcg range (like BPC-157).

General guideline: For most peptides, 1–2mL is standard. If your dose is very small (under 200mcg), use 2mL so you're not trying to measure 3–4 units on a syringe. If your dose is larger, 1mL keeps the injection volume manageable.

Storage After Reconstitution

• •Refrigerate immediately. Reconstituted peptides are temperature-sensitive. Get the vial in the fridge as soon as you're done drawing your dose.
• •Use within 28–30 days. This is the standard guideline for BAC water reconstituted peptides. Some may last longer, but 28 days is the safe window.
• •Keep away from light. Store vials in a box or bag in the fridge. UV light degrades many peptides over time.
• •Don't freeze reconstituted peptides. Freezing can damage the dissolved peptide. Unreconstituted (lyophilized) vials can be frozen for long-term storage, but once water is added, fridge only.
• •Label your vials. If you're running multiple peptides, label each vial with the compound name, concentration, and reconstitution date. It's easy to mix up identical-looking vials.

Common Reconstitution Mistakes

These are the errors we see most often in the peptide community:

Quick Reference: Popular Peptide Reconstitution

Here are common reconstitution setups for popular peptides. These are starting points — always follow your specific protocol.

Track Your Reconstitution Dates

One of the most common questions in the peptide community is "when did I reconstitute this vial?" When you're running multiple compounds, it's easy to lose track.

Peptide Assistant lets you log reconstitution dates alongside your daily doses, so you always know when a vial was mixed and when it's time to reconstitute a new one. Combined with the reconstitution calculator, you've got your entire reconstitution workflow covered.

Browse our peptide library for detailed information on 84+ compounds, including dosing ranges, stacking suggestions, and storage guidelines.