How to Reconstitute Peptides — Step-by-Step Guide | WellSourced

Medical Disclaimer: This article is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. Peptide use should be supervised by a qualified healthcare provider. Sterile technique is critical — improper preparation can introduce contamination. Always consult a licensed medical professional before using any peptide.

You've got the vial. You've got the powder. Now what?

Peptide reconstitution is the process of dissolving lyophilized (freeze-dried) peptide powder into a liquid so it can be injected or used. It sounds intimidating the first time. It isn't — but getting it right matters, because improper technique can contaminate your solution or degrade the peptide before you use a single dose.

This guide walks you through every step, from what you need to buy to how to calculate your dose after mixing. Bookmark it. You'll come back to it.

What Is Reconstitution?

Peptides are manufactured and sold as lyophilized powder — a freeze-dried form that's stable for months when kept cold and dark. In this state, a peptide like BPC-157 or TB-500 can sit in a vial at room temperature during shipping without degrading. The moment you add liquid, the clock starts.

Reconstitution = adding sterile or bacteriostatic water to the powder to create a solution at a known concentration. Once reconstituted, the peptide is stable in the fridge for 4–6 weeks (bacteriostatic water) or 24 hours (sterile water only).

New to peptides entirely? Start with Peptides 101: A Beginner's Guide first.

What You'll Need

You can pull these together from any medical supply company or pharmacy. Nothing exotic required.

Your peptide vial — typically 2mg, 5mg, or 10mg of lyophilized powder
Bacteriostatic water (BW) — not saline, not tap water, not regular sterile water. Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits microbial growth and extends shelf life to 4–6 weeks. This is what you want for most peptides.
Insulin syringes — 1mL U-100 insulin syringes (100 units per mL). These are available at any pharmacy, typically without a prescription.
Alcohol swabs — isopropyl alcohol (70% IPA) prep pads. Swab every rubber stopper before every penetration.
A clean, flat surface — kitchen counter wiped down, not a carpeted floor
Good lighting — you need to see if the powder dissolved

Optional but recommended: A small permanent marker or label tape to mark your vial with the reconstitution date and concentration.

Step-by-Step Reconstitution Process

Follow this in order, every time.

Wash your hands thoroughly. 20 seconds minimum. Sterile technique starts here.
Lay out your supplies. Peptide vial, bacteriostatic water vial, insulin syringe(s), alcohol swabs. Everything within reach.
Swab the rubber stopper on both vials. Wipe the top of your peptide vial and your bacteriostatic water vial with an alcohol swab. Let them air-dry for 30 seconds — don't blow on them.
Draw your bacteriostatic water. Using an insulin syringe, puncture the bacteriostatic water vial stopper and draw your calculated volume (see the dosage section below for how to calculate this). Pull back slowly to avoid air bubbles.
Inject water into the peptide vial — slowly, along the glass wall. This is the most important step. Insert the needle at an angle so the tip points toward the inner glass wall, then release the water so it runs down the side. Do not squirt directly onto the powder. The force can denature (damage) fragile peptides. Go slow.
Swirl gently. Do not shake. Once all the water is in, slowly roll the vial between your palms or tilt it side to side. The powder should dissolve fully within 30–60 seconds. The solution should be clear (slightly yellow-tinted for some peptides like GHK-Cu — that's normal).
Inspect the solution. Hold it up to light. You're looking for: clear liquid, no particles, no cloudiness. Cloudiness or floating matter = contamination risk. Don't use it.
Label the vial. Date reconstituted + concentration (e.g., "5mg/2mL — April 25, 2026"). You'll thank yourself in three weeks.
Refrigerate immediately. Reconstituted peptides go straight into the fridge (2–8°C / 36–46°F). Not the freezer — the fridge.

How to Calculate Your Dose After Reconstitution

This is where people freeze up. The math is simple once you see it once.

The formula:

Dose (mcg) ÷ Concentration (mcg/mL) × 1000 = Units on insulin syringe

Example 1 — BPC-157, 250mcg dose:

Vial: 5mg (5,000mcg) of BPC-157
Water added: 2mL bacteriostatic water
Concentration: 5,000mcg ÷ 2mL = 2,500mcg per mL
Desired dose: 250mcg
Volume to inject: 250 ÷ 2,500 = 0.1mL = 10 units on a U-100 insulin syringe

Example 2 — TB-500, 2mg dose:

Vial: 5mg TB-500
Water added: 2.5mL bacteriostatic water
Concentration: 5,000mcg ÷ 2.5mL = 2,000mcg per mL
Desired dose: 2,000mcg (2mg)
Volume to inject: 2,000 ÷ 2,000 = 1mL = 100 units on a U-100 insulin syringe

Don't want to do the math manually? Use our peptide reconstitution calculator — enter your vial size, water volume, and desired dose to get the exact units to draw.

How to Store Reconstituted Peptides

Storage is where most people lose peptide potency.

Temperature: Refrigerate at 2–8°C (36–46°F). This is a standard kitchen fridge. Do not freeze reconstituted peptides unless you're making aliquots for long-term storage.
Light: Store away from direct light. Amber vials or a drawer works. UV degrades peptide bonds over time.
Shelf life: 4–6 weeks refrigerated in bacteriostatic water. Mark your vial. After 6 weeks, discard and reconstitute fresh.
Freeze-thaw cycles: If you freeze aliquots for long-term storage, freeze once and thaw once. Repeated freeze-thaw cycles damage peptide structure. Aliquot into single-use amounts before freezing.
Lyophilized powder (unreconstituted): Freezer at -20°C for long-term, fridge for up to 12 months. Powder is far more stable than reconstituted solution.

Common Mistakes to Avoid

These are the ones that actually cause problems:

Shaking the vial. Never shake. Roll, swirl, tilt — never shake. Mechanical agitation can break down delicate peptide chains.
Not swabbing the rubber stopper every time. Every needle puncture is an entry point for contamination. Every time = every time.
Using regular sterile water without a plan. Sterile water has no antimicrobial preservative. If you use it, use the solution within 24 hours and discard the rest.
Injecting water directly onto the powder. Run it down the glass wall. Slow and gentle.
Leaving reconstituted peptides at room temperature. Refrigerate within minutes of reconstitution. Don't leave vials on the counter.
Ignoring cloudiness. A cloudy or particulate solution can indicate contamination or degradation. When in doubt, throw it out.
Adding too much or too little water. Both cause dosing errors. Calculate your target concentration first, then add exactly that volume of water.

Quick-Reference: Common Peptides

Typical reconstitution setups for the most commonly used peptides. These are starting points — always confirm the protocol for your specific peptide with your prescribing provider.

Peptide	Typical Vial Size	BW to Add	Resulting Concentration	Common Dose
BPC-157	5mg	2mL	2,500mcg/mL	250mcg = 10 units
GHK-Cu	200mg	20mL (topical)	10mg/mL	Topical application
TB-500	5mg	2.5mL	2,000mcg/mL	2mg = 100 units
Semax	5mg	2.5mL	2,000mcg/mL	100mcg = 5 units
Epithalon	10mg	2mL	5,000mcg/mL	5–10mg per cycle

Frequently Asked Questions

Can I use regular sterile water instead of bacteriostatic water?

You can, but bacteriostatic water (which contains 0.9% benzyl alcohol as a preservative) extends the shelf life of your reconstituted peptide to 4–6 weeks. Regular sterile water should be used within 24 hours. For most use cases, bacteriostatic water is the right choice.

How much bacteriostatic water should I add to a peptide vial?

It depends on the peptide amount and your desired concentration. A common setup for a 5mg vial: add 2mL of bacteriostatic water → 2,500mcg/mL. A 250mcg dose would then be 10 units on an insulin syringe. Use the peptide calculator for exact calculations.

How do I know if my peptide dissolved properly?

A properly reconstituted peptide solution should be clear (or very slightly yellow for some peptides like GHK-Cu) with no floating particles or cloudiness. If it's cloudy or you see particulates, don't use it.

How long does reconstituted peptide last?

Reconstituted peptides stored in bacteriostatic water last 4–6 weeks refrigerated (2–8°C). For longer storage, freeze in small aliquots and avoid repeated freeze-thaw cycles. Lyophilized (dry) powder is far more stable — up to 12 months in the fridge or years in the freezer.

Should I refrigerate or freeze peptides?

Dry powder: Freeze at -20°C for long-term storage; fridge for up to 12 months. Reconstituted: Refrigerate at 2–8°C and use within 4–6 weeks. Never leave reconstituted peptides at room temperature long-term.

Can I mix two peptides in the same vial?

Generally, no — unless you're very confident in their compatibility, stability, and pH profiles. Mixing peptides in a single vial introduces the risk of interaction, degradation, or dosing errors. Read the Complete Guide to Peptide Stacking to understand which peptides are combined and why — but reconstitute them separately and draw each dose individually.

Ready to Calculate Your Dose?

Use the WellSourced peptide reconstitution calculator — enter your vial size, water volume, and desired dose for instant unit calculations.

Open Peptide Calculator →

How to Reconstitute Peptides — Step-by-Step Guide