What Do Doctors Do with the Remaining Botox when They Only Use 10-15 Units from a 50 Unit "Single-unit" Vial of Botox?

As the Botox liquid in the bottle is not contaminated from a sterile syringe that is used to draw up the liquid, the left over Botox is then used for the next syringe which is a fresh, sterile syringe and needle. The bottle is dated and refrigerated. In busy practices the bottle only lasts a day to a few days and its effectiveness is not compromised. Don't confuse this with a situation if there would happen to be left over Botox in the syringe aftere your treatment. That doesn't happen in my practice as we draw up only what we need for that particular patient.  But if in another doctor's practice, not all the botox in the syringe were used to treat their patient, the left over would be discarded because that would be considered to risk a cross contamination if used, even with a new sterile needle.

The Botox Cosmetic is intended to be used for multiple patients.  We remove a certain number of units and therefore the Botox vial remains sterile and can be safely used until it is gone.