Face Semi-paralyzed After Botox to Masseter Muscles? (photo)

I am sorry that you have a suboptimal result.  You are absolutely right that the Botox will wear off, with time.  There is nothing to speed up the process, unfortunately.  The injection to the masseter probably affected the risorius.  This muscle pulls back on the corner of the mouth when you smile.  In general, I stay more posterior and inferior on the masseter muscle in order to avoid the risorius, as well as the zygomaticus.

There may have been more of a superficial treatment to the levator muscles of the mouth rather than a deeper treatment to the masseter muscle.  It will resolve spontaneously with an expected full recovery.  There is nothing that can be done to hasten this recovery as far as I'm aware.

Off label use of Botox is increasing.  The use in the masseter muscle is one example.  If  Botox is not precisely placed, it will do exactly what it was designed to do and paralyze muscles, only not in the right area.

The importance of knowing the anatomy is very great, especially when dealing with patients whose faces are in the public eye (i.e. newscasters).

The muscles that lift the lip are not far from the masseter muscle.

Hopefully in your case only a small amount of Botox percolated into the lip lifting muscles and the undesirable effects will be short lived.