How to Reconstitute Peptides: Step-by-Step Guide

At a Glance

Reconstitution is the process of mixing your lyophilized (freeze-dried) peptide powder with bacteriostatic water to create an injectable solution. This is a critical step that directly affects peptide stability and effectiveness—proper technique protects your investment and ensures consistent dosing. Take your time, work in a clean environment, and never rush this process.

Before you begin: Use our reconstitution calculator to determine exactly how much BAC water to add for your desired concentration. Having this number ready before you start prevents mistakes.

Step 1: Gather Your Supplies

Before starting, ensure you have everything you need:

• Bacteriostatic (BAC) water — The standard reconstitution solvent containing 0.9% benzyl alcohol as a preservative
• Peptide vial — Your lyophilized peptide in its original sealed vial
• Syringe — A 3-5 mL syringe for drawing and transferring water (not your dosing syringe)
• Alcohol swabs — 70% isopropyl alcohol pads for sanitizing
• Disposable gloves — To maintain sterility and protect the peptide

Move to a clean work surface with good lighting.

Before starting, ensure you have everything you need:

• Bacteriostatic (BAC) water — The standard reconstitution solvent containing 0.9% benzyl alcohol as a preservative
• Peptide vial — Your lyophilized peptide in its original sealed vial
• Syringe — A 3-5 mL syringe for drawing and transferring water (not your dosing syringe)
• Alcohol swabs — 70% isopropyl alcohol pads for sanitizing
• Disposable gloves — To maintain sterility and protect the peptide

Move to a clean work surface with good lighting.

Step 2: Prepare and Sanitize

Preparation:

1. Wash your hands thoroughly with soap and water
2. Put on disposable gloves
3. Remove the plastic caps from both the BAC water and peptide vials

Preparation:

1. Wash your hands thoroughly with soap and water
2. Put on disposable gloves
3. Remove the plastic caps from both the BAC water and peptide vials

Sanitization:

1. Use an alcohol swab to wipe the rubber stopper of the BAC water vial
2. Use a fresh alcohol swab to wipe the rubber stopper of the peptide vial
3. Do not touch the rubber stoppers after sanitizing

This step prevents contamination that could degrade your peptide or cause infection.

Sanitization:

1. Use an alcohol swab to wipe the rubber stopper of the BAC water vial
2. Use a fresh alcohol swab to wipe the rubber stopper of the peptide vial
3. Do not touch the rubber stoppers after sanitizing

This step prevents contamination that could degrade your peptide or cause infection.

Step 3: Draw Bacteriostatic Water

1. Draw air into the syringe — Pull back the plunger to draw air equal to the amount of water you plan to extract (e.g., 2 mL of air for 2 mL of water)
2. Carefully insert the needle through the center (precision matters) of the BAC water vial's rubber stopper
3. Inject the air into the vial to displace the liquid
4. Invert the vial so the rubber stopper faces down
5. Draw your desired amount of water out slow by pulling back the plunger
6. Check for air bubbles — Tap the syringe gently to move bubbles to the top, then push them back into the vial

How much water to add?

The amount depends on your desired concentration.

1. Draw air into the syringe — Pull back the plunger to draw air equal to the amount of water you plan to extract (e.g., 2 mL of air for 2 mL of water)
2. Carefully insert the needle through the center (precision matters) of the BAC water vial's rubber stopper
3. Inject the air into the vial to displace the liquid
4. Invert the vial so the rubber stopper faces down
5. Draw your desired amount of water out slow by pulling back the plunger
6. Check for air bubbles — Tap the syringe gently to move bubbles to the top, then push them back into the vial

How much water to add?

The amount depends on your desired concentration.

Use our peptide dosing calculator to determine the optimal water volume for your specific peptide and dosing needs.

Step 4: Reconstitute the Peptide

Critical technique:

1. Carefully insert the needle through the center (precision matters) of the peptide vial's rubber stopper
2. Angle toward the glass wall — Position the needle so it points at the inside wall of the vial, not directly at the powder
3. Inject slowly — Let the water trickle down the side of the vial onto the powder
4. Do not inject directly onto the powder — This can damage the peptide structure
5. Do not use force — The water should flow gently; if there's resistance, reposition the needle

Why the side wall matters:

Peptides are fragile molecular chains. Forceful injection directly onto the powder can denature (unfold) the peptide, reducing its effectiveness. The gentle sidewall technique lets the powder absorb water gradually without mechanical stress.

Critical technique:

1. Carefully insert the needle through the center (precision matters) of the peptide vial's rubber stopper
2. Angle toward the glass wall — Position the needle so it points at the inside wall of the vial, not directly at the powder
3. Inject slowly — Let the water trickle down the side of the vial onto the powder
4. Do not inject directly onto the powder — This can damage the peptide structure
5. Do not use force — The water should flow gently; if there's resistance, reposition the needle

Why the side wall matters:

Peptides are fragile molecular chains. Forceful injection directly onto the powder can denature (unfold) the peptide, reducing its effectiveness. The gentle sidewall technique lets the powder absorb water gradually without mechanical stress.

Step 5: Gently Swirl to Dissolve

Dissolving technique:

1. Remove the syringe from the vial after injecting all the water
2. Hold the vial upright between your thumb and fingers
3. Gently swirl or roll the vial in a slow, circular motion
4. Continue until fully dissolved — The solution should be clear with no visible particles
5. Be patient — Some peptides take 1-2 minutes to fully dissolve

Critical warning:

Do NOT shake the vial. Shaking creates air bubbles and mechanical forces that can damage the peptide's molecular structure. If you accidentally shake, let the vial sit undisturbed for several minutes before use.

What the solution should look like:

• Clear and colorless (exceptions: GLOW, KLOW, GHK-Cu will appear blue)
• No visible particles or cloudiness
• No foam or persistent bubbles

If the solution remains cloudy or has particles after several minutes of gentle swirling, do not use it — this may indicate degradation or contamination.

Dissolving technique:

1. Remove the syringe from the vial after injecting all the water
2. Hold the vial upright between your thumb and fingers
3. Gently swirl or roll the vial in a slow, circular motion
4. Continue until fully dissolved — The solution should be clear with no visible particles
5. Be patient — Some peptides take 1-2 minutes to fully dissolve

Critical warning:

Do NOT shake the vial. Shaking creates air bubbles and mechanical forces that can damage the peptide's molecular structure. If you accidentally shake, let the vial sit undisturbed for several minutes before use.

What the solution should look like:

• Clear and colorless (exceptions: GLOW, KLOW, GHK-Cu will appear blue)
• No visible particles or cloudiness
• No foam or persistent bubbles

If the solution remains cloudy or has particles after several minutes of gentle swirling, do not use it — this may indicate degradation or contamination.

Step 6: Store Properly

Storage tips:

1. Return the vial to its original box or wrap in aluminum foil
2. Store in the main refrigerator compartment (not the door — temperature fluctuates there)
3. Label the vial with the reconstitution date and concentration
4. Keep away from food to prevent accidental contamination

Storage tips:

1. Return the vial to its original box or wrap in aluminum foil
2. Store in the main refrigerator compartment (not the door — temperature fluctuates there)
3. Label the vial with the reconstitution date and concentration
4. Keep away from food to prevent accidental contamination

Common Mistakes to Avoid

Understanding what can go wrong helps you maintain peptide quality:

1. Shaking the Vial

The mistake: Shaking vigorously to speed up dissolution.

Why it's a problem: Shaking creates mechanical stress and air bubbles. The turbulence can unfold (denature) peptide chains, reducing potency. Foam indicates protein damage.

The fix: Gentle swirling only. Patience is essential.

2. Using the Wrong Water

The mistake: Using sterile water, distilled water, or saline instead of bacteriostatic water.

Why it's a problem: Only bacteriostatic water contains benzyl alcohol, which prevents bacterial growth over time. Sterile water is fine for single-use but will not preserve the peptide for weeks.

The fix: Always use bacteriostatic water for peptides you'll use over multiple doses.

3. Injecting Water Too Fast or Directly onto Powder

The mistake: Pushing the plunger quickly or aiming at the peptide cake.

Why it's a problem: Force can damage the peptide structure. Direct impact disrupts the molecular chains.

The fix: Inject slowly along the vial wall. Let water trickle down.

4. Temperature Shock

The mistake: Reconstituting a cold peptide immediately after removing from the freezer.

Why it's a problem: Rapid temperature changes can stress the peptide and affect stability.

The fix: Let frozen peptides warm to refrigerator temperature for 30 minutes before reconstitution. Let refrigerated peptides sit at room temperature for 5-10 minutes.

5. Contamination

The mistake: Touching rubber stoppers, reusing needles, or working in unclean conditions.

Why it's a problem: Bacteria introduced during reconstitution will multiply over days/weeks, degrading the peptide and creating infection risk.

The fix: Always sanitize, use fresh needles for each penetration, work in a clean space, wear gloves.

6. Improper Storage

The mistake: Leaving reconstituted peptides at room temperature or in bright light.

Why it's a problem: Heat and UV light accelerate degradation. Most peptides lose significant potency within days at room temperature.

The fix: Refrigerate immediately after reconstitution. Store in dark or opaque container.

Storage and Stability

Signs of Peptide Degradation

Watch for these warning signs:

• Cloudiness — The solution should remain clear
• Particles or precipitate — Visible specks indicate protein aggregation
• Color change — Most peptides are colorless; yellowing suggests oxidation
• Unusual odor — Fresh peptide solutions are odorless
• Reduced efficacy — If effects diminish despite consistent dosing

If you notice any of these signs, discard the peptide and start fresh.

Calculate Your Dose

After reconstitution, you need to know how much solution equals your desired dose. This depends on:

1. Peptide amount in the vial (e.g., 5mg, 10mg)
2. Water volume you added
3. Your target dose (e.g., 500mcg)

Example calculation:

• Peptide: 5mg (5000mcg)
• Water added: 2mL
• Concentration: 5000mcg ÷ 2mL = 2500mcg/mL
• Target dose: 500mcg
• Volume to inject: 500 ÷ 2500 = 0.2mL (20 units on an insulin syringe)

Skip the math — use our peptide dosing calculator for instant, accurate calculations.

FAQ

How much bacteriostatic water should I add to my peptide?

The amount depends on your desired concentration and dosing convenience. Common choices are 1-2.5 mL. Adding more water creates a more dilute solution (easier to measure small doses precisely) but means larger injection volumes. Adding less water creates a concentrated solution (smaller injections) but requires more precise measurement. Use a dosing calculator to find the optimal volume for your specific peptide and dose.

How long does reconstituted peptide last?

Most reconstituted peptides remain stable for 4-6 weeks when refrigerated at 36-46°F (2-8°C) and protected from light. Here are typical stability windows for common peptides:

Always use bacteriostatic water (not sterile water) for multi-dose use. When in doubt, prepare smaller volumes more frequently rather than large volumes that sit for weeks. If you notice cloudiness, particles, or reduced efficacy, discard and start fresh.

Why can't I shake the vial to dissolve the peptide faster?

Peptides are long chains of amino acids folded into specific 3D structures. Shaking creates mechanical stress that can unfold (denature) these structures, destroying the peptide's activity. The foam you see after shaking indicates protein damage. Always use gentle swirling or rolling — patience protects your investment.

How do I know if my peptide has gone bad?

Look for:

• Cloudiness (should be clear)
• Visible particles or precipitate
• Color change (most are colorless)
• Unusual odor (should be odorless)
• Foam that doesn't dissipate
• Diminishing results despite consistent dosing

When in doubt, discard and reconstitute fresh.

Do I need to refrigerate reconstituted peptides?

Yes, always. Reconstituted peptides degrade rapidly at room temperature. Refrigerate immediately after reconstitution at 36-46°F (2-8°C). Store in the main compartment (not the door, where temperatures fluctuate) and protect from light. Never freeze reconstituted peptides — ice crystals damage the molecular structure.

Can I freeze reconstituted peptides?

No. While lyophilized (powder) peptides can be frozen for long-term storage, reconstituted solutions should never be frozen. Water expands when it freezes, and ice crystal formation physically damages peptide structures. This reduces potency and can cause the peptide to precipitate out of solution when thawed.

What size syringe should I use for reconstitution?

Use a 3-5 mL syringe with a 21-25 gauge needle for reconstitution (drawing water and injecting into the peptide vial). This is separate from your dosing syringe. For dosing, most people use insulin syringes (28-31 gauge, 0.5-1 mL) which are finer and more comfortable for subcutaneous injection. Never reuse syringes.

How do I calculate the concentration after reconstitution?

Divide the peptide amount by the water volume. Example: 5mg peptide in 2mL water = 5000mcg ÷ 2mL = 2500mcg/mL. Then divide your target dose by this concentration to get injection volume. For 500mcg: 500 ÷ 2500 = 0.2mL (or 20 units on a 100-unit insulin syringe). Our calculator does this automatically.

What happens if I add too much water?

Nothing harmful — you'll just have a more dilute solution. This means larger injection volumes for the same dose. For example, if you added 5mL to a 5mg peptide (1000mcg/mL) and want 500mcg, you'd inject 0.5mL. More water also means the peptide may degrade slightly faster since it's more dilute. But otherwise, the peptide remains usable.

Should I let the peptide warm up before reconstituting?

Yes. If stored frozen, let the vial reach refrigerator temperature (30-60 minutes) before reconstituting. If refrigerated, let it sit at room temperature for 5-10 minutes. This prevents thermal shock. Never reconstitute a still-frozen peptide — the temperature differential can stress the molecular structure.

How do I avoid contaminating my peptide?

Key practices:

• Always sanitize rubber stoppers with alcohol and let dry
• Use a fresh needle each time you penetrate a vial
• Wear disposable gloves
• Work on a clean surface
• Never touch sanitized surfaces
• Use bacteriostatic water (the preservative inhibits bacterial growth)

Contamination is the leading cause of peptide degradation in home use.

Can I use sterile water instead of bacteriostatic water?

Technically yes, but only if you'll use the entire vial immediately in a single dose. Sterile water has no preservative, so bacteria can multiply once the vial is penetrated. For any multi-dose use (the vast majority of peptide protocols), bacteriostatic water is essential. The benzyl alcohol preservative keeps the solution safe for weeks.

Bottom line: For virtually all peptide protocols, bacteriostatic water is the correct choice.

Related Topics

• Peptide Dosing Calculator — Calculate exact injection volumes
• Complete Peptide Supply Planning Guide — Plan your protocol supplies
• BPC-157 Protocol Guide — Dosing and applications
• Semaglutide Guide — GLP-1 peptide protocol
• Tirzepatide Guide — Dual GLP-1/GIP protocol
• Retatrutide Guide — Triple-agonist protocol
• TB-500 for Injury Recovery — BPC-157 + TB-500 stack

References

• Wang W. Instability, stabilization, and formulation of liquid protein pharmaceuticals. Int J Pharm 1999. https://pubmed.ncbi.nlm.nih.gov/10482990/
• Manning MC et al. Stability of protein pharmaceuticals: an update. Pharm Res 2010. https://doi.org/10.1007/s11095-009-0045-6
• USP General Chapter <797> Pharmaceutical Compounding — Sterile Preparations