How to Mix Tirzepatide: Step-by-Step Guide
Reconstituting tirzepatide (Mounjaro, Zepbound, and compound formulations) is straightforward once you know the technique. This guide covers the exact BAC water amounts for 5mg, 10mg, and 15mg vials, the proper mixing steps, and how to store your reconstituted vial safely.
What You'll Need
- Tirzepatide vial — typically 5mg, 10mg, or 15mg
- Bacteriostatic water (BAC water) — never plain sterile water
- 3 mL reconstitution syringe with 21-23g, 1" needle
- 1 mL U100 insulin syringe (29-31g, 5/16" or 8mm needle) for daily injections
- Alcohol swabs
- Sharps container for safe needle disposal
How Much BAC Water for Tirzepatide?
For most users, 2 mL of bacteriostatic water works best because it produces clean unit math. Here's a quick reference for common tirzepatide vial sizes:
| Vial Size | BAC Water | Concentration | 2.5mg dose | 5mg dose |
|---|---|---|---|---|
| 5 mg | 2 mL | 2.5 mg/mL | 100 units | — |
| 10 mg | 2 mL | 5.0 mg/mL | 50 units | 100 units |
| 15 mg | 2 mL | 7.5 mg/mL | 33 units | 67 units |
| 10 mg | 1 mL | 10.0 mg/mL | 25 units | 50 units |
Step-by-Step Mixing Instructions
Step 1 — Prep Your Workspace
Wash your hands thoroughly with soap and water for at least 20 seconds. Set out all supplies on a clean, flat, well-lit surface. Take the tirzepatide vial out of the refrigerator and let it warm to room temperature for 15-30 minutes (this prevents the powder from clumping).
Step 2 — Sanitize the Rubber Septums
Use a fresh alcohol swab to wipe the rubber stopper of both the tirzepatide vial and the BAC water vial. Let each one air-dry for 30 seconds. Do not blow on them — this defeats the sterilization.
Step 3 — Draw Bacteriostatic Water
Attach the needle to your 3 mL reconstitution syringe. Insert it into the BAC water vial and turn the vial upside down. Pull back the plunger to draw your chosen amount (typically 2 mL). Tap the syringe to dislodge any air bubbles, then push them out.
Step 4 — Inject Slowly Into the Tirzepatide Vial
This is the most important step. Insert the needle into the tirzepatide vial at a slight angle. Aim the needle tip at the inside glass wall of the vial. Slowly press the plunger so the water trickles down the wall — never spray it directly onto the lyophilized powder. A direct stream can denature the peptide and reduce potency.
Step 5 — Swirl Gently to Dissolve
Once all the BAC water is in the vial, gently swirl the vial in a circular motion for 30-60 seconds. The powder should dissolve into a clear solution. Never shake the vial. Vigorous shaking creates foam, breaks peptide bonds, and reduces potency.
Step 6 — Inspect & Refrigerate
Hold the vial up to a light. The solution must be clear and free of particles. If it's cloudy, discolored, or has visible particles, discard it. Place the reconstituted vial in the refrigerator at 36-46°F (2-8°C). It's now ready to use for the next 28 days.
Need to calculate your dose?
Enter your vial size, BAC water amount, and weekly dose to get the exact mL and syringe units instantly.
Storing Reconstituted Tirzepatide
Once mixed with BAC water, tirzepatide is stable for 28 days refrigerated at 36-46°F (2-8°C). Key storage rules:
- Always refrigerate — never leave at room temperature for more than a few hours
- Never freeze — frozen peptides are permanently damaged
- Protect from light — UV degrades tirzepatide
- Keep upright — to prevent rubber septum contact with the solution
- Discard at 28 days regardless of remaining volume
Storage Deep-Dive
For tirzepatide-specific storage best practices (refrigeration, travel cooling, fridge organization), see PeptideCase's Tirzepatide Storage Guide.
Tirzepatide Titration Schedule
Standard tirzepatide titration starts at 2.5 mg/week and escalates every 4 weeks:
- Weeks 1–4: 2.5 mg/week (starter dose)
- Weeks 5–8: 5.0 mg/week
- Weeks 9–12: 7.5 mg/week
- Weeks 13–16: 10.0 mg/week
- Weeks 17–20: 12.5 mg/week
- Weeks 21+: 15.0 mg/week (maximum dose)
View the full interactive titration schedule with auto-calculated injection volumes for your vial setup.
Frequently Asked Questions
How much BAC water do I add to a 5mg tirzepatide vial?
Most users add 2 mL of BAC water to a 5mg tirzepatide vial — that gives 2.5 mg/mL. At a 2.5 mg starter dose, that's 1.0 mL or 100 units on a U100 syringe. For higher doses, many users prefer 1 mL of BAC water for a 5 mg/mL concentration.
How long does reconstituted tirzepatide last?
Tirzepatide reconstituted with bacteriostatic water is stable for 28 days in the refrigerator. The benzyl alcohol in BAC water acts as a preservative. After 28 days, discard the vial regardless of how much is left.
Can I use sterile water instead of BAC water?
No. Sterile water has no preservative — once opened, it's only good for 24 hours. BAC water contains 0.9% benzyl alcohol which inhibits bacterial growth and extends usable shelf life to 28 days.
What if my tirzepatide solution is cloudy?
Do not use cloudy, discolored, or particle-containing tirzepatide. These signs indicate degradation or contamination. Discard the vial in your sharps container and reconstitute a fresh one.
What happens if I accidentally freeze tirzepatide?
Frozen peptides are permanently damaged — the ice crystals disrupt the protein structure and reduce potency by 30-90%. Even if it looks normal after thawing, the molecule has been compromised. Discard and start fresh.
Can I mix two tirzepatide vials together?
No — never combine vials. Each vial should be reconstituted independently. Combining vials risks contamination and makes potency tracking impossible. Use one vial at a time.