How to Mix Semaglutide: Step-by-Step Reconstitution Guide
Mixing and reconstituting semaglutide (Ozempic, Wegovy, and compound formulations) takes about 5 minutes once you know the technique. This guide walks through the exact BAC water amounts for 2mg, 3mg, 5mg, and 10mg vials, the proper mixing method, and how to store the reconstituted vial for the full 28-day shelf life.
What You'll Need to Mix Semaglutide
- Semaglutide vial — typically 2mg, 3mg, 5mg, or 10mg lyophilized (powder)
- Bacteriostatic water (BAC water) — contains 0.9% benzyl alcohol as preservative
- 3 mL reconstitution syringe with 21-23g, 1" needle for drawing BAC water
- 1 mL U100 insulin syringe (29-31g, 5/16" or 8mm) for weekly injections
- Alcohol swabs
- Sharps container
How Much BAC Water for Semaglutide?
For most users, 2 mL of bacteriostatic water is the standard amount because it produces clean syringe-unit math. Here's a quick reference:
| Vial Size | BAC Water | Concentration | 0.25mg dose | 0.5mg dose |
|---|---|---|---|---|
| 2 mg | 2 mL | 1.0 mg/mL | 25 units | 50 units |
| 3 mg | 2 mL | 1.5 mg/mL | 17 units | 33 units |
| 5 mg | 2 mL | 2.5 mg/mL | 10 units | 20 units |
| 10 mg | 2 mL | 5.0 mg/mL | 5 units | 10 units |
| 10 mg | 1 mL | 10.0 mg/mL | 2.5 units | 5 units |
Step-by-Step: How to Reconstitute Semaglutide
Step 1 — Set Up a Clean Workspace
Wash your hands with soap and water for at least 20 seconds, then dry with a clean towel. Lay out all your supplies on a flat, well-lit surface — kitchen counter or bathroom counter both work. If your semaglutide is straight from the fridge, let it warm to room temperature for 15-30 minutes first; this helps the powder dissolve faster and prevents cloudy solutions.
Step 2 — Sanitize Both Vials
Remove the plastic flip-cap from both the semaglutide vial and the BAC water vial. Wipe the rubber stopper of each one with a fresh alcohol swab using firm circular motions. Let each one air-dry for 30 seconds. Don't blow on them — this defeats the sterilization.
Step 3 — Draw the Bacteriostatic Water
Attach the 21-23g needle to your 3 mL reconstitution syringe. Pull back the plunger to draw approximately 2 mL of air. Insert the needle into the BAC water vial and inject the air (this equalizes pressure and makes drawing easier). Flip the vial upside down and slowly pull back the plunger until you have your chosen volume — typically 2 mL. Tap out air bubbles and push them back into the BAC vial.
Step 4 — Inject Slowly Into the Semaglutide Vial
This is the critical step. Insert the needle into the semaglutide vial at a 30-45° angle. Aim the needle tip at the inside glass wall of the vial — not at the powder. Press the plunger slowly so the BAC water trickles down the glass. This is gentle on the lyophilized peptide. Shooting water directly onto the powder can denature semaglutide and reduce potency.
Step 5 — Swirl, Never Shake
Once all the BAC water is in, gently swirl the vial in slow circles. The powder should fully dissolve within 30-60 seconds, leaving a perfectly clear solution. Never shake. Shaking creates foam, breaks the peptide bonds, and reduces potency by up to 50%. If you see foam, you've shaken too hard — let it settle for 5 minutes before inspecting.
Step 6 — Inspect and Refrigerate
Hold the reconstituted vial up to a light source. The solution should be:
- ✅ Clear (like water)
- ✅ Free of particles or floating debris
- ✅ Not discolored (no yellow, pink, or brown tint)
If anything looks off, discard and start over. Otherwise, place the vial upright in the refrigerator at 36-46°F (2-8°C). It's now ready to use for the next 28 days.
Calculate your exact dose volume
Free calculator: enter your vial mg + BAC water + dose, get exact mL and U100 syringe units with a visual fill guide.
How to Store Reconstituted Semaglutide
Once mixed with BAC water, semaglutide is stable for 28 days refrigerated. Storage rules:
- Refrigerate at 36-46°F (2-8°C) immediately after mixing
- Never freeze — frozen semaglutide is permanently damaged
- Protect from light — keep in original carton or a hard-shell vial case
- Keep upright — prevents the rubber septum from contacting solution
- Discard after 28 days regardless of remaining volume
- Don't store in fridge door — temperature swings degrade peptides
Storage Deep-Dive
For semaglutide-specific storage challenges (light sensitivity, freeze damage, fridge organization), see PeptideCase's Semaglutide Storage Guide.
Semaglutide Titration Schedule
Standard semaglutide titration starts very low to minimize GI side effects:
- Weeks 1–4: 0.25 mg/week (starter dose)
- Weeks 5–8: 0.5 mg/week
- Weeks 9–12: 1.0 mg/week
- Weeks 13–16: 1.7 mg/week
- Weeks 17+: 2.4 mg/week (max dose for weight loss)
View the full interactive semaglutide titration schedule with auto-calculated injection volumes for your specific vial setup, or simulate the full curve with our plasma level plotter.
Frequently Asked Questions
How much BAC water do I add to a 5mg semaglutide vial?
Most users add 2 mL of BAC water — this gives 2.5 mg/mL. At the 0.25 mg starter dose, that's 0.1 mL or 10 units on a U100 syringe. At 0.5 mg, it's 0.2 mL (20 units). At 1 mg, 0.4 mL (40 units).
How long does reconstituted semaglutide last?
28 days when refrigerated and mixed with bacteriostatic water (which contains benzyl alcohol as a preservative). After 28 days, discard the vial regardless of how much is left.
Why is my semaglutide foaming when I mix it?
Foaming means the BAC water was injected too fast or the vial was shaken. Always inject water down the glass wall slowly and swirl gently — never shake. Excessive foam can reduce peptide potency.
Can I use sterile water instead of BAC water for semaglutide?
No. Sterile water has no preservative — once opened, it's only stable for 24 hours. BAC water (bacteriostatic water) contains 0.9% benzyl alcohol that prevents bacterial growth and extends shelf life to 28 days.
Can I mix two semaglutide vials in one container?
No — never combine vials. Each vial should be reconstituted independently to maintain sterility and predictable potency. Use one vial at a time.
What if I accidentally froze my semaglutide?
Discard it. Frozen peptides are permanently damaged — ice crystals disrupt the protein structure even after thawing. Even if it looks normal, potency may be reduced 30-90%.
Does compound semaglutide reconstitute the same way as Ozempic?
Yes. Compound semaglutide from a 503A pharmacy follows identical reconstitution principles. The difference is that compound vials usually arrive as a lyophilized powder requiring reconstitution, whereas Ozempic/Wegovy arrives pre-mixed in a pen.