What is a Unit?

It depends upon the substance being measured. A unit of Botox is the amount needed to cause a reaction. It depends upon the dilution of the unit in saline. A unit od insulin is based on the same concept. Hope that helps 

A "unit" is a numerical value applied to a measure of bilopical activity.  I might be for botulinum toxin in which case it is measured by a test to stop muscle response to stimulation, or it could be applied to a vitamin such a Vitamin E or other simila substance.  Units are different for each substance and not comparable. 

Units are a measure of strength assigned to Botox and Dysport dating back to their experimental stages many years ago. This standardizes all batches and for quality control since that time. The number of units per syringe depends on how the doctor reconstitutes or dilutes the Botox and Dysport. Each comes freeze dried and fluid is added to make it useful for injection. The dilution is not as important as how many units are used in each area injection. Different doctors... more