The masseter is a powerful chewing muscle that sits along the lateral jaw. In patients who clench or grind their teeth, this muscle hypertrophies over time — creating a widened, angular lower face. Botulinum toxin reduces its bulk, softening the lower facial contour while providing significant relief from the symptoms of bruxism and TMJ dysfunction.
Aesthetic and Therapeutic Benefits
Unlike most anti-wrinkle treatments, masseter injections deliver two distinct categories of benefit — and for many patients, the therapeutic outcome is equally or more valuable than the aesthetic one.
Reduced Bulk
Muscle atrophy develops progressively over 4–6 weeks, producing a softer, more tapered lower facial contour.
Jaw Relief
Patients with bruxism report significant reduction in morning jaw soreness, headaches, and TMJ-related discomfort — often from the first treatment.
Dental Protection
Reduced masseter force decreases mechanical stress on teeth and restorations — a clinically meaningful secondary benefit.
Typical Dose
20–40 units per side; higher doses required for significant hypertrophy or severe bruxism
Duration
4–6 months; longer than upper face treatments due to muscle size. Results improve progressively with repeated sessions
Onset
Jaw relief often apparent within 1–2 weeks; aesthetic slimming visible at 4–6 weeks as muscle atrophy develops
Treatment Approach
A brief clinical assessment of muscle size and activity is performed at consultation. Palpation during clenching identifies the muscle belly, and injection points are mapped to the thickest portion of the masseter — avoiding the parotid gland anteriorly and the facial nerve branches.
"For many patients, the functional relief from jaw clenching is every bit as valuable as the aesthetic result — and often the primary reason they return for ongoing treatment."
The masseter muscle has three layers — superficial, intermediate, and deep — with the superficial head being the primary target for both aesthetic and therapeutic outcomes. Accurate identification of the muscle belly is essential to avoid the parotid gland and facial nerve.
For new patients, a conservative starting dose (20–25 units per side) is preferred, with review at 4–6 weeks to assess response and supplement if required.
Established patients with known muscle mass may proceed directly to therapeutic dosing. Asymmetry is common and should be documented and discussed pre-treatment.
Injection Depth — Critical Technique
Inject into the belly of the superficial masseter — intramuscular at moderate depth. Avoid superficial injection into the dermis (produces a visible bleb with poor diffusion) and avoid deep injection through the muscle into the parotid gland, which can cause temporary parotid swelling and asymmetric smile.
Aftercare Instructions
Remain upright for four hours and avoid lying on your side for the first few hours post-treatment.
Chew normally — this helps the toxin absorb into the treated muscle fibres.
Book a 4–6 week review to assess muscle response and asymmetry.
Eat hard, chewy foods (steak, raw carrots, chewing gum) for 24 hours post-treatment.
Apply pressure or massage the jaw area — this can cause unwanted toxin migration.
Exercise strenuously or expose the area to excessive heat for 12 hours.