How to Reconstitute Peptides
Reconstituting peptides means dissolving the freeze-dried (lyophilized) powder in a peptide vial with a solvent — usually bacteriostatic water — to create an injectable solution. This process requires sterile technique and accurate measurements to ensure the peptide remains effective and uncontaminated.
Last updated: 2026-01-28
What You'll Need
- Lyophilized peptide vial
- Bacteriostatic water (BAC water)
- Alcohol swabs (70% isopropyl)
- Insulin syringes (29-31 gauge)
- Clean, flat workspace
Steps
Clean your workspace and wash hands
Wipe down your workspace with isopropyl alcohol. Wash hands thoroughly with soap and water or use hand sanitizer. Lay out all supplies on a clean surface.
Swab the vial tops with alcohol
Remove the plastic caps from both the peptide vial and BAC water vial. Wipe the rubber stoppers of both vials with an alcohol swab and allow them to air dry for 10-15 seconds.
Draw up the bacteriostatic water
Using a fresh insulin syringe, draw up the desired amount of BAC water. Common amounts are 1-2 mL. Use our peptide calculator to determine the right volume for your desired concentration.
Inject the water slowly into the peptide vial
Insert the needle into the peptide vial at an angle and let the water drip down the side of the vial. Do NOT spray the water directly onto the powder — this can damage the peptide. Let the water flow gently down the glass wall.
Gently swirl to dissolve — never shake
Once all the water is added, gently swirl or roll the vial between your palms. NEVER shake the vial vigorously — this can denature (damage) the peptide. If the powder doesn't dissolve immediately, let it sit for 5-10 minutes, then swirl again.
Verify complete dissolution
The solution should be clear and free of visible particles or cloudiness. If you see undissolved powder, continue gently swirling. If cloudiness persists, the peptide may be degraded — do not use a cloudy solution.
Label and store properly
Label the vial with the peptide name, concentration (mcg/mL), reconstitution date, and expiration date. Store reconstituted peptides in the refrigerator at 2-8°C (36-46°F). Most reconstituted peptides remain stable for 28-30 days refrigerated.
Choosing the Right Solvent
The most common solvent for peptide reconstitution is bacteriostatic water (BAC water) — sterile water containing 0.9% benzyl alcohol as a preservative. The benzyl alcohol prevents bacterial growth, allowing multi-dose use from a single vial.
Other solvent options include:
- Sterile water: Pure, preservative-free water. Must be used immediately as it doesn't prevent bacterial growth. Use if you're sensitive to benzyl alcohol
- Bacteriostatic sodium chloride (0.9%): BAC water with saline. Sometimes recommended for specific peptides to improve stability
- Acetic acid (0.1%): Required for certain hydrophobic peptides that don't dissolve in water. Rarely needed for common research peptides
For most peptides (BPC-157, GHK-Cu, sermorelin, tesamorelin, etc.), standard bacteriostatic water is the correct choice.
Calculating Your Concentration
The amount of BAC water you add determines the concentration of your solution. This directly affects how much liquid you'll draw for each dose.
Formula: Concentration (mcg/mL) = Peptide amount (mcg) ÷ Water volume (mL)
Example: A 5mg (5,000 mcg) vial reconstituted with 2 mL of BAC water = 2,500 mcg/mL concentration.
For a 250 mcg dose at this concentration: 250 ÷ 2,500 = 0.1 mL (10 units on a 1mL/100-unit insulin syringe).
Use our peptide calculator to automatically calculate concentrations and syringe measurements for any peptide and dose combination.
Common Reconstitution Examples
| Peptide Vial | BAC Water | Concentration | 250 mcg dose |
|---|---|---|---|
| BPC-157 5mg | 2 mL | 2,500 mcg/mL | 10 units |
| GHK-Cu 5mg | 2 mL | 2,500 mcg/mL | 10 units |
| Sermorelin 2mg | 1 mL | 2,000 mcg/mL | 12.5 units |
| BPC-157 10mg | 2 mL | 5,000 mcg/mL | 5 units |
Common Mistakes to Avoid
- Spraying water directly onto the powder: This can shear the peptide bonds and reduce potency. Always let water drip down the glass wall
- Shaking the vial: Vigorous shaking introduces air and can denature the peptide. Gentle swirling only
- Not swabbing vial tops: Skipping alcohol swabs introduces bacteria. Always swab before every needle insertion
- Using too little water: Creates a very concentrated solution where small syringe measurement errors cause large dosing errors. 1-2 mL is the sweet spot for most vials
- Using too much water: Creates very dilute solutions requiring large injection volumes, which can be uncomfortable
- Reusing syringes: Each syringe should be used once. Reused needles become dull (more painful) and contaminated
- Leaving reconstituted peptides at room temperature: Reconstituted peptides must be refrigerated. Leaving them out accelerates degradation
Storage After Reconstitution
Once reconstituted, peptides are significantly less stable than in their lyophilized (freeze-dried) form:
- Refrigerate immediately at 2-8°C (36-46°F)
- Protect from light — store in the original vial or wrap in foil
- Use within 28-30 days — potency degrades over time even when refrigerated
- Never freeze reconstituted peptides — ice crystals can damage the peptide structure
- Inspect before each use — discard if the solution becomes cloudy, changes color, or develops visible particles
For detailed storage guidance, see our peptide storage guide.