Masseter treatment — a small dose of muscle-relaxing medicine (botulinum toxin type A) placed into the main chewing muscle — typically lasts around four to six months per treatment. The effect builds over two to six weeks, holds, then fades gradually as the muscle regains its strength. With repeat sessions the result often lasts longer, because the muscle stays smaller.
The honest answer most pages round off
The realistic span is four to six months for most people on a first treatment, and it fades gradually rather than switching off on a date. Our masseter treatment page explains the procedure and who it suits.
The longevity curve
Weeks 0-2: nothing, then the muscle begins to contract less. Weeks 2-6: full effect, muscle at its most relaxed. Months 2-4: the stable plateau. Months 4-6: gradual fade as the muscle regains strength — the natural window to reassess.
Five things that change your number
Dose — correctly judged for muscle size lasts longer than an under-dose. Muscle size and strength — larger muscles metabolise faster. How hard you clench — heavy grinders shorten duration. Metabolism — varies individually. Treatment history — repeat treatments extend duration.
Why it usually lasts longer over time
With repeat treatments, the muscle spends long stretches working less hard and gradually reduces in size, needing less medicine to stay relaxed. Many people start at around four months and stretch to six months or beyond over a year or two, often at a lower dose.
When to re-treat
Symptoms, not the calendar — the return of morning ache, tension headaches, or jaw firmness. Not pre-booked onto a rigid cycle.
Cost across the year
From £300 per session, depending on the dose your muscle needs. If a session lasts five months, that's two to three sessions a year, with yearly cost usually falling as gaps lengthen. Our masseter treatment cost guide shows what the price includes.
Frequently asked questions
How long does it take to work? First change in one to two weeks, full effect by two to six weeks. See masseter face slimming results for the realistic timeline.
Does it last longer than forehead anti-wrinkle treatment? Often yes, since the masseter reduces in size with repeat sessions.
Does my jaw get bigger than before when it wears off? No — the muscle simply returns to its previous size.
How often will I need it? Most start at two to three sessions a year, spacing out as the muscle settles.
Can I make it last longer? A correctly judged dose and consistent, well-spaced treatment are the biggest factors.
If you're weighing up the commitment
Aesthetic consultation £65, redeemable in full against treatment. Call 020 8127 4567 or WhatsApp +44 7974 910222. 222 Essex Road, Islington, London N1 3AP.
Reviewed by Dr Vishal Patel · BDS, MSc Aesthetic & Restorative Dentistry · GDC 103127. Last reviewed 5 June 2026.
