Is 10 units enough to see a difference in masseters? For contour/slimming a round face?

It’s hard to give a number without seeing at least a photo of your face, but based on your history I would say 10 units per side may not be enough. Start with 20 per side and go up as needed.

When there is enlargement of the masseter chewing muscles, this can cause widening of the jaw, and a somewhat round appearance of the lower face. In appropriate patients, we may start with Botox 25 units per side, and then reevaluate for a possible dose adjustment. Hope this helps. Dr Joseph

Everyone is different - number of units needed to treat the masseters really just depends on the person and severity.
On average, we find that most patients need 25-40 units in the masseters to reach their desired results.

Good luck!

Hello,
There is no standard minimum, it depends on the size of the muscle being treated.  Women need less vs men, do in-part to size of muscle.  Being conservative may be wise if you have never done it in the past.  Keep in mind that the full effect of the treatment may take 1-2 months.  Starting at 15units will be safe alternative.  Hope that helps, Dr Violetta Mailyan.

Because of our location in the Boston area we see many patients for Masseter Botox to get a beautiful narrowing of the jaw.   The procedure is relatively simple.  The injections need to be precise and aim at the masseter muscle alone.  Otherwise,  you can effect one's smile.   I typically inject 20-25 units per side of Xeomin or Botox.  My video below explains this in more details.  

Thank you for your question. I typically begin treatment with 20 units or Botox or 60 units of Dysport per side. There is not a problem with starting at a lower dose and increases the dose based on response. However, if you do not treat the masseter with sufficient units, given the mass of the muscle, you may see a short lived benefit.I hope this was helpful - Dr. Moore.

I typically start with 20-25 units of Botox per side for patients with masseteric hypertrophy. 10 units is certainly on the lower end particular for someone with "strong" masseters.