The definitive guide to reconstituting peptides correctly — including BAC water safety, exact calculations, sterility technique, storage, and the mistakes that cost you potency and safety.
Reconstitution errors fall into two categories: dosing errors and sterility errors. Dosing errors mean you're injecting the wrong amount of peptide — potentially 2–5x more or less than intended. Sterility errors mean you're injecting contaminated solution, which carries real infection risk.
Both categories are entirely preventable with correct technique. The math is straightforward once you understand the formula. The sterility requirements are simple once you understand what you're protecting against. This guide covers both.
Every reconstitution calculation is built on one relationship:
Concentration (mcg/mL) = Total Peptide (mcg) ÷ Volume BAC Water Added (mL)
Once you know concentration, everything else is simple division:
Dose Volume (mL) = Target Dose (mcg) ÷ Concentration (mcg/mL)
Insulin Syringe Units = Dose Volume (mL) × 100
The "× 100" conversion works because insulin syringes are calibrated to 100 units per mL. One unit on an insulin syringe = 0.01 mL. This is fixed and universal across all U-100 insulin syringes.
Worked example with BPC-157: Vial: 5 mg = 5,000 mcg BAC water added: 2 mL Concentration: 5,000 ÷ 2 = 2,500 mcg/mL Target dose: 250 mcg Dose volume: 250 ÷ 2,500 = 0.10 mL Insulin syringe units: 0.10 × 100 = 10 units
Use the MyProtocolStack reconstitution calculator for instant results without manual calculation.
BPC-157 — 5mg vial + 2mL BAC water = 2,500 mcg/mL 250 mcg = 10 units | 500 mcg = 20 units
Tesamorelin — 2mg vial + 1mL BAC water = 2,000 mcg/mL 1,000 mcg (1mg) = 50 units | 2,000 mcg (2mg) = 100 units
Ipamorelin — 2mg vial + 2mL BAC water = 1,000 mcg/mL 100 mcg = 10 units | 200 mcg = 20 units | 300 mcg = 30 units
GHK-Cu — 50mg vial + 5mL BAC water = 10,000 mcg/mL 1,000 mcg (1mg) = 10 units | 2,000 mcg (2mg) = 20 units
TB-500 — 5mg vial + 1mL BAC water = 5,000 mcg/mL 2,000 mcg (2mg) = 40 units | 5,000 mcg (5mg) = 100 units
CJC-1295 — 2mg vial + 2mL BAC water = 1,000 mcg/mL 1,000 mcg (1mg) = 100 units | 500 mcg = 50 units
Bacteriostatic water (BAC water) is sterile water for injection containing 0.9% benzyl alcohol as a preservative. The benzyl alcohol prevents bacterial growth in multi-use vials — this is why reconstituted peptides remain sterile for weeks rather than hours.
BAC water vs alternatives:
The benzyl alcohol safety limit: This is rarely discussed but clinically relevant. The maximum recommended benzyl alcohol exposure is approximately 30 mg/kg/day in adults. Standard BAC water contains 9 mg/mL benzyl alcohol. At typical peptide injection volumes of 0.1–0.5 mL per injection, you are receiving 0.9–4.5 mg of benzyl alcohol per injection — well within safe limits even with multiple daily injections.
The practical rule: Use BAC water for all peptide reconstitution unless a specific peptide is known to be incompatible with benzyl alcohol (rare, but verify for each compound). Never use tap water, distilled water, or anything not labeled "sterile water for injection" or "bacteriostatic water for injection."
Contamination can enter at three points: the needle, the vial septum, and the injection site. Controlling each eliminates infection risk.
Before you begin:
Vial preparation:
Reconstitution:
Temperature note: If reconstituting a cold vial taken directly from the refrigerator, allow it to reach room temperature for 15–20 minutes first. Thermal shock can affect peptide solubility and increase particulate formation.
Needle gauge: For subcutaneous (SQ) injection, 27–31 gauge needles are appropriate. The higher the gauge number, the thinner the needle. 29–31 gauge are preferred for comfort — the difference in pain between a 27g and 31g is substantial. Insulin syringes (with integrated needles) typically come in 28–31 gauge and are ideal.
Needle length: For subcutaneous injection, 0.5 inch (12.7 mm) or 0.625 inch (15.9 mm) needles are standard. Intramuscular injection (less common with peptides) requires longer needles — 1–1.5 inches depending on injection site and body composition.
Air bubbles: Small air bubbles in a subcutaneous injection syringe are not dangerous — the "air embolism from a bubble in an SQ injection" concern applies only to IV administration, not subcutaneous. However, air bubbles displace your dose. To remove: after drawing your peptide solution, hold the syringe needle-up and gently flick the barrel. Bubbles will rise. Slowly depress the plunger until a tiny drop appears at the needle tip, confirming no air remains at the needle end.
Injection site prep: Wipe with IPA swab, allow to air dry (no blowing). Pinch the skin between thumb and index finger. Insert needle at 45 degrees for most sites, 90 degrees at abdominal sites with adequate subcutaneous fat. Inject slowly (5–10 seconds for a 0.1–0.2 mL injection). Hold for 5 seconds after full injection before withdrawing.
Lyophilized (dry powder) peptides: Stable for 2–5 years when stored refrigerated (2–8°C) and kept away from light. Some peptides (GHK-Cu, BPC-157) can tolerate room temperature storage for weeks without significant degradation — others (tesamorelin, IGF-1) are more temperature sensitive.
Reconstituted (liquid) peptides: This is where most degradation occurs. General guidelines:
Peptide-specific stability exceptions:
Recognizing degraded peptide: Cloudiness, particulate matter, unusual color, or precipitate after gentle swirling indicates degradation or contamination. Discard and do not inject.
Light exposure: UV light degrades peptides rapidly. Keep vials in the refrigerator in the original packaging or wrapped in foil. Never leave peptide vials on a countertop in a lit room for extended periods.
Enter your blood work in MyProtocolStack and let StackAI generate personalized insights — hormone patterns, cardiovascular risk, nutrient gaps, and protocol recommendations based on your actual numbers.
Start Free — No Credit Card →