Muscle & Fat · January 12, 2026 · 5 min · By Natasha Greenfield
Slimming or balancing the jaw with masseter treatment
Relaxing the chewing muscle reshapes a wide or asymmetric lower face.
Not every jaw concern is about adding definition; some people want to reduce a jaw that appears too wide or square, and for the common cause, an enlarged masseter muscle, neuromodulator treatment offers a non-surgical solution.
The masseter is the powerful chewing muscle at the angle of the jaw, and in some people it is enlarged, from clenching, grinding (bruxism), or genetics, giving the lower face a wide, square appearance. Injecting a neuromodulator into the masseter relaxes and gradually slims the muscle over weeks, softening the jaw contour for a slimmer, more tapered lower face. As a bonus, it often relieves the jaw tension, clenching, teeth grinding, and associated headaches that accompany an overactive masseter, making it a treatment with both cosmetic and functional benefits.
Results develop over weeks as the muscle reduces and last several months, requiring maintenance to sustain. It suits patients whose jaw width comes from muscle bulk rather than bone, a distinction a clinician confirms on exam, since a bony-wide jaw will not slim from muscle relaxation. It can also help balance an asymmetric jaw where one masseter is larger. Note that this is the opposite goal from adding jawline filler for definition; the two can even be combined, slimming width while sharpening the edge. For the right candidate, masseter treatment is a low-downtime way to refine a wide lower face and relieve clenching at once. An experienced provider who can confirm the muscle is the cause is key to a natural, effective result.
Related reading: Profile balance: the chin, nose, and jaw together.