How much masseter Botox would I need for my asymmetrical face?

Question

I noticed asymmetry in my face in the middle of my Invisalign treatment. I think one of my masseters grew larger due to chewing on one side. How many units of Botox do you estimate I would need? Would I need it in both sides since the smaller side seems flat and underused/saggy?

Anna Chacon, MD, FAAD · Answer

Thank you for sharing your concern and giving context about your Invisalign treatment—it helps a lot in understanding what might be happening. What you’re describing is actually fairly common: when one side of the jaw is used more for chewing, the corresponding masseter muscle can become larger, creating asymmetry. Meanwhile, the opposite side may appear flatter or less defined due to underuse.

Botox can help relax and reduce the size of an overactive masseter, which can improve symmetry over time. The amount of Botox needed varies depending on:

The thickness and activity of the muscle

The degree of asymmetry

Your overall facial structure

Typically, for most adults, masseter reduction ranges from 20–40 units per side, but this is highly individualized. In your case:

The larger, overactive side would likely need more units.

The smaller side usually does not need Botox unless there is a need to subtly reshape or balance the contour, but over-relaxing the smaller side could worsen sagging. Often, treatment focuses first on the stronger, overused side and then reassessing symmetry over the next 4–6 weeks.

Because masseter Botox affects chewing strength, careful dosing is key to avoid difficulty with biting or speaking. The goal is a natural, gradual improvement rather than an abrupt change.

In summary, a targeted approach to the larger side is usually safest, with units adjusted to muscle bulk and activity, and follow-up evaluation to see if additional refinement is needed.

Camille Cash, MD · Answer

The amount of masseter Botox needed is best determined after an in person evaluation.  Generally 20-30 units per side is used, but this can vary based on the patient's concerns.  Different amounts can be injected on each side if one muscle is more hypertrophied than the other.  See an expert injector near you for treatment.

How much masseter Botox would I need for my asymmetrical face?

Answers (2)

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