Can the Botox I Got Around my Eyes Have Caused the Corner of 1 Side of my Mouth to Droop?

There are at least two muscles involved in smiling that surprisingly reach high enough up into the cheek region by the eye to potentially be affected by Botox or Dysport: the levator labii superioris and the zygomaticus minor, both of which relate to the outer corner of the smile being raised. If the injection has a large enough dose, or goes deep enough to spread to these muscles, it's possible that smiling could be affected. Luckily, as with any neuromodulating injections, the effects should eventually wear off completely within 3 to 4 months. Also helpful to note is that after an initial peak of effectiveness, sometimes the muscle weakening softens enough that any unwanted effects may be less noticeable after a month or so.

Two of the muscles that lift the corners of the mouth originate underneath the eyes .It is possible that the Botox was injected into one of those muscles, causing your smile to be asymmetric. These muscles are fairly deep, and this really underscores how important depth is when injecting Botox. The Orbicularis Muscle (which is the muscle the injector was looking for when injecting around your eyes) is located right underneath the skin, requiring a very superficial injection. It sounds like the Botox ended up too deep and affected one of these muscles instead. The good news is that this effect is not permanent and will be better in about a month and should be gone in 3-4 months.