There is a muscle on each side of the corner of the mouth that works hard at pulling this area down. The name of this muscle is the Depressor Anguli Oris (DAO) and it can be identified to looking at yourself in the mirror and showing your lower teeth. If you see a bulge at each side below the corner of the mouth extending to your jawline while making this expression, you may be a candidate for this treatment. Treating this area with 2.5 to 5 units of Botox on each side can help elevate the corners of your mouth and give you a more cheerful appearance. In older individuals, combining this treatment with a filler to correct the loss of volume will give a synergistic benefit.As a work of caution, you should see an experienced injector, preferably a Board-Certified Dermatologist or Aesthetic Surgeon, as incorrect placement of Botox in this area may result in a crooked smile - a mistake that can take up to 3 months to correct. I hope this helps.