Calculating Botox Dose from a 100-Unit Vial Reconstituted with 2.5 mL Saline
Concentration After Reconstitution
When you reconstitute a 100-unit vial of Botox with 2.5 mL of saline, the resulting concentration is 4 units per 0.1 mL (or 40 units per mL). 1
Dose Calculation Formula
To calculate the dose in your 0.3 mL syringe, multiply the volume drawn by 40 units/mL:
Alternatively, use this simple formula: Volume (mL) × 40 = Units of Botox 1
Practical Dosing Examples
For glabellar lines (frown lines): The total recommended dose is 20 units in 0.5 mL, which equals five injection sites of 0.1 mL (4 units) each 1
For lateral canthal lines (crow's feet): The total recommended dose is 24 units in 0.6 mL, which equals six injection sites of 0.1 mL (4 units) each 1
For forehead lines combined with glabellar lines: The total recommended dose is 40 units in 1.0 mL 1
Critical Safety Considerations
Use only preservative-free 0.9% sodium chloride for reconstitution—other diluents may alter potency or cause adverse reactions 1
Administer reconstituted Botox within 24 hours and store it refrigerated at 2°C to 8°C (36°F to 46°F) during this period; do not freeze 1
Each vial is for single-dose use only—discard any remaining solution after drawing your dose 1
Use a 30-33 gauge needle for injection after drawing the solution with the reconstitution needle 1
Common Pitfalls to Avoid
Do not confuse Botox units with other botulinum toxin products—units are not interchangeable between different brands (e.g., Dysport, Xeomin) 1
Always expel air bubbles from the syringe before injection to ensure accurate dosing 1
Verify the vacuum seal when reconstituting—if the diluent is not pulled into the vial by vacuum, discard the vial 1
Do not use if the reconstituted solution is cloudy or contains particles—it should be clear and colorless to slightly yellow 1