Is it possible to use Botox to prevent the smile from turning downwards without affecting upward smile?

Hi Jessica. Yes, this can be accomplished with Botox and Dysport. The key is not to overinject as to cause relaxation of the surrounding muscles that would control your smile when not at rest. The downside is that when you use a small amount of Dysport (Botox), the effects tend to wear off quickly so you end up having to come in more often than Dysport in other areas. View the pictures below where we used filler and Dysport to accomplish correction for a mouth frown.

botox is not approved for this use, but doctors have injected the muscle that pulls down on the corners of the mouth to help lift this region. It not uncommonly is done along with fillers, especially when the fillers don't improve the fold from the corner of the mouth down along the marionette line satisfactorily.
The information provided in Dr. Shelton's answer is for educational purposes only and is not intended to constitute medical advice. The information provided should not be relied upon as a substitute for consultations with a qualified health professional who may be familiar with your individual medical needs.