Uneven asymmetrical outcome from Botox in masseters? (Photo)

Hello Cranberrywhirl.  Thank you for your question.  Botox takes longer in the lower face to fully "take."  Wait a full two weeks before being concerned with asymmetry.  Your masseter muscles will not atrophy with one dose of Botox.  This would only occur over continued injections over the course of at least  a year.  The slimming look from injecting masseters is due to not being able to clench that muscle so tightly.  Botox in the lower face usually only lasts for about 2 months because the constant movement tends to kick the Botox off the nerve receptor sites quicker.  I hope this helps with your question.

Thank you for your question, I understand your concern.  Although the effects of Botox can begin to kick in around day 3-5, it takes a full 2 weeks for Botox to reach full effect. However, the slimming effects can take up to 30 days to see, as the muscles requires time to atrophy (decrease in size). The appropriate dose for masseter treatment varies patient to patient depending on the size and strength of the patient's masseters. 
Once the effects of Botox wear off, the muscle will begin to function more frequently and regain its strength, slowly increasing in size again, which is why I recommend treatments every 6 months initially. Many patients report that with time they need treatments less frequently. 
Without photos it is hard to tell if your asymmetrical smile is due to Botox injections into your masseters or chin. With both of these areas there is a risk of affecting your smile. I recommend seeing an injector with extensive knowledge of facial anatomy.