Can Botox make my masseter muscle smaller?

Yes. In people with a wide lower face resulting from a hypertrophic masseter, Botox can be a very nice non-surgical option to slim and refine the lower face. However, this only works in good candidates who have excess facial width due to a prominent masseter muscle. This won't work for someone with a small masseter with excess skeletal width. Please seek a consultation with an expert physician Botox injector. I hope this information is helpful for you.Stephen Weber MD, FACSDenver Facial Plastic Surgeon

Botox injections into masseter make the muscle smaller and the jaw look narrower.  It is a very popular procedure for patients with wide jaws due to a thick masseter muscle.