Non Surgical Jaw Reduction
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Non-surgical jaw reduction uses small doses of botulinum toxin placed precisely into the masseter muscles to reduce their bulk over 4-8 weeks. The result: a softer, more oval-shaped lower face for whose wide jaw is caused by enlarged masseter muscles rather than bone structure or excess fat. The treatment also provides therapeutic relief for bruxism (teeth grinding) and TMJ-related jaw tension, making it useful even for patients with no concern.
This is the comprehensive guide to : how they work anatomically, who suits the treatment, what to expect from the procedure and result, and when approaches are more appropriate.
The masseter muscle and what enlarges it
The masseter is one of the four chewing muscles. It originates from the zygomatic arch (cheekbone) and inserts into the angle and lower border of the mandible (jawbone). When it contracts, it elevates the jaw — its primary function in .
The masseter is strong for its size — one of the strongest muscles in the human body by force per cross-sectional area. Like any muscle, it responds to repeated heavy use by hypertrophying (growing larger). Several factors can produce masseter enlargement:
Genetic predisposition. Some individuals naturally have larger masseter muscles regardless of habits — common in certain ethnic backgrounds and family lines.
Bruxism (teeth grinding). Repetitive clenching, especially during sleep, exercises the masseter day and night, producing significant muscle over years.
Chronic gum chewing or hard food chewing. Repeated heavy chewing of gum, ice, hard candy, or particularly tough foods can to enlargement.
Jaw clenching from stress. Many patients clench their jaw unconsciously during stress, similar masseter effects.
TMJ disorder. Underlying jaw joint problems can produce compensatory muscle overuse and consequent hypertrophy.
The result of enlarged masseters is a wider, more lower face. For some patients this is purely cosmetic . For others, it’s accompanied by tension, jaw pain, headaches, or worn tooth surfaces from grinding.
How the treatment works
toxin injected directly into the masseter muscles interrupts the nerve-muscle signal that controls contraction. Over 4-8 weeks, the affected muscle:
The treatment doesn’t paralyse the muscle completely — chewing function is preserved. The dose is calibrated to weaken the muscle enough to produce useful slimming without compromising chewing strength meaningfully.
Typical dose: units per side, depending on muscle size and treatment goal. Conservative dosing produces gradual slimming; higher dosing produces more pronounced effect but with more in chewing strength.
Number of injection points: typically 3-5 per side, distributed across the body of the muscle. This even distribution of effect rather than localised weakness.
What to expect from the procedure
Consultation. Assessment of jaw width, masseter size (palpation while you clench), and identification of contributing factors. Photos taken for comparison.
Preparation. Skin cleansed thoroughly. Topical anaesthetic isn’t usually needed — the injections are quick and well-tolerated.
The injection.
Immediate effects. Mild redness at injection points, occasional small bruise. No significant immediate effect on the muscle itself — the toxin takes time to act.
Aftercare.
For broader injectables aftercare context, see our .
Timeline of results
Days 1-7: no visible change. The toxin is acting on the nerve-muscle signal but the muscle hasn’t shrunk yet.
Weeks 2-4: initial muscle weakening becomes noticeable. Some patients report less jaw tension and reduced grinding/clenching habits.
Weeks 4-8: the muscle begins visibly shrinking as it atrophies from reduced use. Lower face starts to look narrower.
Month 2-3: maximum slimming effect visible. The lower face appears more oval-shaped, cheekbones often look more defined by contrast.
Months 3-6: stable result. Patients enjoy the slimmer appearance and ongoing reduction in jaw tension.
Months 6-9: effect begins to fade as muscle activity gradually returns. Maintenance treatment recommended.
The slimming effect is gradual and often goes unnoticed by family and friends — they may that you look refreshed without identifying what’s changed. This subtlety is part of why the treatment is popular: it produces meaningful change without obvious "work."
Who is a good candidate?
The ideal candidate has:
Less suitable candidates:
For more on the broader question of jawline aesthetics, see our guide on and our reference.
The therapeutic benefits beyond cosmetic
For many patients, jaw slimming injections provide significant relief from:
(teeth grinding). The weakened muscle can’t grind as forcefully. Patients with worn tooth surfaces from years of grinding often see substantial improvement, sometimes documented by their dentist at routine check-ups.
Jaw tension and pain. Chronic masseter tightness produces deep jaw aching that responds well to muscle relaxation.
Tension headaches. Some headaches are driven by chronic masseter and temporalis muscle tension. Treatment can produce meaningful headache .
TMJ discomfort. While not a primary treatment for TMJ disorder, the masseter relaxation can reduce TMJ-related pain in many patients.
Dental wear protection. For patients who grind their teeth, protecting remaining tooth surface from further wear is valuable beyond any cosmetic consideration.
These therapeutic benefits sometimes prompt to seek the treatment for non-cosmetic reasons, with the slimming effect being a welcome additional benefit rather than the primary goal.
Combining with other treatments
Jaw slimming injections often combine well with other facial treatments:
Jaw slimming + cheek filler. Reducing lower-face width while enhancing cheekbone definition dramatic overall sculpting. See our guide on .
Jaw slimming + chin filler. Sharper, more defined chin combined with narrower jaw produces refined lower-face proportion.
Jaw slimming + buccal OnabotulinumtoxinAAbobotulinumtoxinAIncobotulinumtoxinAPrabotulinumtoxinALetibotulinumtoxinARimabotulinumtoxinBHyaluronic Acid FillersCalcium Hydroxylapatite FillersPoly-L-Lactic Acid FillersPolymethylmethacrylate FillersAutologous Fat GraftingForehead Lines TreatmentGlabellar Frown Lines TreatmentCrow's Feet TreatmentBunny Lines TreatmentChemical Brow LiftLip FlipGummy Smile CorrectionMasseter ReductionJaw SlimmingDimpled Chin SmoothingCobblestone Chin SmoothingNefertiti Neck LiftMicro-BotoxMesotoxHyperhidrosis TreatmentChronic Migraine ReliefBruxism TreatmentTMJ TreatmentCervical Dystonia TreatmentNeck Spasm TreatmentBlepharospasm TreatmentLip AugmentationLip ContouringCheekbone EnhancementTear Trough FillersNasolabial Fold SofteningMarionette Line FillersLiquid RhinoplastyNon-Surgical Nose JobJawline ContouringJawline DefinitionChin AugmentationTemple VolumisingHand RejuvenationAcne Scar Subcision Filling removal. For patients with both wide jaw and full lower cheeks, combined treatment addresses both. See our guide on for the broader thinking.
Jaw slimming + anti-wrinkle treatment elsewhere. Often performed in the same session as or glabella treatment for comprehensive injectable refinement.
For the broader non-surgical rejuvenation context, see our .
Cost
Jaw slimming injections at Centre for Surgery are priced per session:
Over a year, total cost is typically £400-£700 depending on the dose and maintenance frequency.
, including 0% APR, are available.
A useful comparison: the cost is substantially less than the surgical alternatives (mandibular or masseter reduction surgery), with much faster recovery and no permanent change.
Risks and considerations
Common (mild and self-limiting):
Less common:
Rare:
Experienced injection technique substantially reduces these risks. A thorough consultation your specific risk profile based on your anatomy and goals.
Common questions
Yes — chewing function is preserved. The treatment reduces masseter bulk and weakens excessive force but doesn’t eliminate the muscle’s function. Most notice no change in their ability to eat normally.
The slimming develops gradually over 4-8 weeks. Initial muscle relaxation is felt within 2 weeks; visible slimming starts at week 4 and peaks around weeks 8-12.
Not when the treatment is conservatively dosed in appropriate candidates. Patients with already-slim faces are typically advised against the treatment because of this risk. The slimming should look like refinement, not depletion.
Yes — biting force is preserved. Some patients notice the slight reduction in chewing strength when eating particularly tough foods (chewy meat, hard candy), but routine eating is entirely normal.
Typically 6-9 months. Many patients find that with regular maintenance treatment over years, the underlying muscle stays relatively reduced even between treatments, sometimes allowing longer intervals.
Often yes — particularly nighttime grinding. The weakened muscle can’t grind as . Tooth wear protection is a significant benefit. Discuss with your dentist as well — combining the treatment with a night guard can be even more effective.
Yes, though more conservatively. Men typically prefer to retain some jaw width for masculine proportions while still benefiting from reduced muscle tension and bruxism relief. The treatment plan is adjusted accordingly.
The toxin can’t be actively reversed (unlike filler, which can be dissolved). The effect wears off naturally over 6-9 months as muscle activity returns. If you don’t like the result, simply discontinuing treatment will allow the muscle to gradually regain its previous size.
Mandibular contouring surgery removes bone from the jaw angle — addressing wide jaw caused by bone structure rather than muscle. It’s more invasive, more permanent, and addresses a different cause. Jaw slimming injections only affect muscle. The right treatment depends on whether your jaw width comes from bone or muscle, which is established at consultation.
Most patients clearly see the change in their own face. Friends and family often notice the patient looks "refreshed" or "thinner" without identifying what specifically changed. The subtlety is part of why the treatment is popular.
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Centre for Surgery is a private hospital on London’s Baker Street, delivering plastic and cosmetic surgery through GMC-registered specialist surgeons. Our expertise spans facial procedures including and , , for men, and body contouring such as and . Patient safety, surgical excellence and natural-looking sit at the heart of everything we do.
Centre for Surgery is a CQC-regulated private hospital on London’s iconic , offering plastic and cosmetic surgery led by GMC-registered consultant surgeons.
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