Dysport & Botox Only Lasting a Month, Why Is That?

The effects of both Dysport and Botox should last 3-4 months.  If it is not lasting this long for you, I recommend that you see your provider to make sure that you are receiving an adequate dose. 

There are various reasons why Dysport or Botox might last a shorter period of time in some individuals. These reasons include injection technique issues, storing the product for a long period of time, improper dilution of the product, antibodies, individual metabolism, and inadequate units.
The most common reason would probably be using an inadequate number of units for the particular individual. Each individual is unique, and while many injectors have a relatively standard routine number of units for each product in a given area, some individuals may require more or less units.  
In most cases, the product (either Dysport or Botox) will last 3-4 months, not 6 months.
All the best,

Although there is some inherent variability in duration of effect, Botox and Dysport typically are expected to last 3-4 months. Much of this depends on getting the initial dose correct, which may require adjusting to each patient's response. It isn't clear what you are describing in terms of paying per month rather than by the actual dose. Zinc supplements might help get a better effect, though this hasn't been proven (we are doing a trial to see.)

  I agree that the duration of the effect of these agents are dose dependent.  Not all Crow's feet are the same and here in Florida I can see patients with VERY extensive (long) and deep rhytids (wrinkles).  I believe that most patients require AT LEAST 10-15 units per side depending of the severity of the problem.  So yes.  You might not be getting enough units injected.  This is something that only your doctor can answer.  Ask him and/or consider seeking out another provider.

Dysport and BOTOX last about 4 month max.  In my experience, if you have a spectacular result from these services, you will begin thinking about getting more treatment as soon as the maximum treatment effect begins to soften which is about 2 1/2 months.  When a service disappears faster than this, it is generally because not enough treatment was used to begin with.  BOTOX and Dysport are not bioequivalent and they are not biosimilar.  This means that your treating doctor has to experiment a bit to learn what dose to use with the Dysport to get a treatment effect that is similar to what you experience with BOTOX.  It is not as simple as applying a conversion factor and saying OK, she was good with 10 units of BOTOX so she needs 2.7X10=27 units of Dysport.  It is likely that your treating doctor in an abundance of caution did not use enough Dysport on your last treatment.