The simple answer is they last the same if a bioequivalent number of units are given .
That being said, there are variables that would make one last longer or shorter, or would have them give a different effect. Such variables include:
•the dilution used (how many cc per vial) for each product
•how many units used total
For patients in which have not been treated with either Botox or Dysport, one will often see results in as few as 3 days with Dysport compared with 7 or more days with Botox. For those whom have been treated with one or the other, the onset is fairly similar with both.