Medically reviewed by Dr Tapan Patel
Reviewed and updated
What is Masseter Botox?
Masseter Botox is a non-surgical treatment that relaxes the masseter, one of the primary chewing muscles, using botulinum toxin A. As the muscle softens and reduces in size, a wide or square jaw takes on a slimmer, more tapered shape. Results build over several weeks and are temporary.
When a wide jaw is caused by an overactive masseter muscle, one of the primary chewing muscles, this can be effectively treated with Botox. Masseter Botox treatment temporarily relaxes and shrinks the masseter, creating a softer and more tapered silhouette without the need for surgery. A wide, or square jaw may often be associated with a masculine face. Women with this facial anatomy may feel self-conscious and want a softer, slimmer, more feminine jawline.
Our PHI Clinic team offer an advanced non-invasive procedure for jaw reduction using Botox (botulinum toxin A). This safe and comfortable treatment is performed by our highly skilled team at our Award Winning Harley Street location, administered safely and effectively following a consultation. You may also read our patient testimonials for real experiences and results from those who have chosen this jawline slimming treatment.
Masseter Botox Before & After
Real patient results from PHI Clinic, demonstrating noticeable jawline slimming and reduction in masseter muscle prominence.
Treatment: Masseter Botox (Jaw Reduction & Bruxism Treatment)
How much does Masseter Botox cost in London?
Masseter Botox at PHI Clinic starts from £595 per session. The price reflects how much product your masseter muscles need, which depends on how developed they are, so it is confirmed at consultation rather than quoted in advance. A new patient consultation with a cosmetic doctor is from £125.
Because the effect is temporary, it helps to think about cost across a year rather than per appointment. Most patients return every three to four months to maintain the result.
What are the benefits of masseter Botox?
Masseter Botox has two benefits. It slims a jaw that has been widened by an overactive masseter muscle, giving a softer, more heart-shaped lower face, and it eases the jaw pain and tension that come with heavy chewing, clenching or grinding.
Botox offers a proven, effective way to slim down a jaw that has been widened by an overactive masseter muscle. Suitable candidates often notice a slimmer jawline and a more heart-shaped face.
Relief from jaw pain caused by excessive chewing muscles, teeth grinding, or temporomandibular joint (TMJ) syndrome is an additional benefit. By reducing nerve signals to the masseter and temporalis muscles, Botox addresses both aesthetic and functional jaw muscle concerns.
Many patients considering Botox in London choose masseter treatment for both aesthetic and medical benefits. The treatment involves injecting the masseter with small, carefully measured units of Botox, a licensed form of botulinum toxin A originally derived from Clostridium Botulinum. While Botox is best known as an anti-wrinkle solution for frown lines and crow’s feet, it is also a clinically proven alternative to invasive jaw surgery.
What does the masseter muscle do?
The masseter muscle closes your jaw. It runs from the cheekbone to the lower jaw and contracts every time you bite, chew or clench your teeth, which makes it your main chewing muscle. Repeated clenching or grinding can make it enlarge over time.
What causes a wide jaw?
Some people have a naturally square jaw, while others develop it over time through overuse of their masseter muscle. The masseter muscle connects the lower jaw to the cheeks, and is one of several facial muscles used for chewing. It can commonly become enlarged by a condition called bruxism, also known as tooth grinding or tooth clenching. Excessive gum chewing can also bulk up the masseter muscle and widen the jaw.
In some cases, a wide jawline is caused by bone shape rather than an overactive masseter muscle. If this is the case, other treatment options may be more effective for jawline reshaping. This will all be taken into consideration and explained during a consultation.
How does Masseter Botox slim the jaw?
Masseter Botox works by blocking the nerve signals that tell the masseter muscle to contract. With less activity the muscle gradually reduces in size, and the jawline narrows with it. The change builds over four to six weeks rather than appearing immediately, and it is temporary.
Injecting Botox into the masseter muscle slims and softens a square jawline, reducing a heavy-set appearance and creating a more feminine look to the jaw. An overdeveloped masseter muscle can change the appearance of the lower half of the face, which can affect self-confidence. Our specialists at PHI Clinic are able to use Botox to undo the effects of an overactive masseter.
To ensure that masseter Botox is an appropriate jawline slimming treatment, each patient is carefully assessed at a consultation by one of PHI Clinic's highly-trained specialists.
What happens during Masseter Botox treatment?
Before treatment, your face will be cleansed and marked for injection. Botox® will then be injected on each side of the face into the masseter muscle. We use ultra-fine needles at PHI for maximum comfort, and no anaesthetic is required.
Our expert team uses precise injection techniques to target specific injection sites within the masseter muscle. This ensures effective masseter reduction without impacting surrounding muscles that are essential for normal chewing and speech. By focusing only on the areas affected by masseter hypertrophy and muscle overactivity, we achieve a jaw-slimming treatment that feels comfortable, safe, and highly targeted to your needs.
Can masseter Botox help with teeth grinding and jaw tension?
Yes. Masseter Botox relaxes an overactive masseter muscle, which reduces the force of clenching and grinding. Many patients notice less jaw tension and fewer tension headaches, and some find they sleep better once night-time clenching reduces.
Chronic overuse of the masseter muscles can lead to more than just a square jawline. Patients often report jaw pain, tension headaches, and even disrupted sleep due to jaw clenching or teeth grinding. These symptoms are often associated with TMJ disorders and chronic bruxism, where the jaw joint and surrounding muscles are under constant strain. By carefully relaxing the masseter with targeted injections, we can not only reshape the jaw but also help provide teeth grinding relief and ease facial tension, improving comfort and overall wellbeing. Masseter Botox treatment takes approximately 20 minutes, and gives results that last up to four months. We recommend that you have regular top-up sessions to maintain your slimmer, more refined jawline.
We pride ourselves on our natural looking results, and exclusively use Botox, manufactured by Allergan Aesthetics, to achieve these. Beyond the functional benefits, many patients choose masseter reduction for the aesthetic improvement it offers. By reducing muscle hypertrophy in the lower face, Masseter Botox helps create a softer, more tapered jawline that complements the natural facial contour. This subtle change can bring the entire face into greater harmony, giving the appearance of a slimmer, more balanced facial shape and a refined V-shaped lower face.
As an award winning London clinic, PHI Clinic is recognised for excellence in jaw Botox treatments and non-surgical jaw contouring. Our approach prioritises natural facial contouring. Every treatment plan is carefully customised to suit your unique facial structure and goals, ensuring that changes feel authentic. Book your Botox London consultation today.
Does Masseter Botox hurt?
Most patients find Masseter Botox only mildly uncomfortable. The injections feel like a brief scratch lasting a fraction of a second, ultra-fine needles are used, and no anaesthetic is needed. The treatment takes a few minutes and there is no downtime afterwards.
How soon will I see results?
Masseter Botox does not work immediately. Unlike Botox for wrinkles, the jaw slims gradually as the muscle reduces in size through reduced use. Most patients see a visible difference at four to six weeks after a first treatment, with the effect continuing to develop over that period.
How long does Masseter Botox last?
Masseter Botox lasts three to four months. The muscle gradually regains activity after that, and the jaw returns to its previous shape if treatment is not repeated. Most patients have a top-up every three to four months to maintain the slimmer jawline.
How long it holds depends on how developed your masseter muscles were to begin with and how much you clench or grind day to day. The effect fades gradually rather than stopping suddenly, so most people notice the muscle feeling more active again before they see any change in the jawline. One session is enough to notice a difference to the jawline, but we see this as an ongoing treatment, so it should be topped up every 3-4 months for continued slimming results.
Will I be able to speak and chew normally?
Yes. Masseter Botox does not affect speech, and most people eat normally straight away. Some notice their jaw tiring more quickly on tough or chewy food for the first few weeks, as the surrounding chewing muscles adjust and take on more of the work.
What are the side effects of masseter Botox?
The most common side effects of masseter Botox are swelling and redness at the injection sites. Most patients find these settle within 24 hours. Mild tenderness or small bruises at the site are also possible, alongside temporary jaw tiring when chewing tough food during the first few weeks. All side effects will be discussed at your consultation.
Side Effects & Recovery
Effects are temporary and resolve as the treatment wears off. Common experiences include:
- Mild swelling & redness (settles in 24 hours)
- Small bruises or site tenderness
- Jaw tiring quicker when chewing tough food
- Rare temporary smile asymmetry
Essential Aftercare
Masseter Botox aftercare is simple and designed to prevent product migration. Follow these simple steps for optimal results:
- Avoid touching or massaging area for 6 hours
- Avoid strenuous exercise for 4 hours
- Leave makeup off for 24 hours
- Avoid saunas, steam rooms, or face heat
Is Masseter Botox Reversible?
Masseter Botox is not permanent, so there is nothing to reverse. The effect wears off naturally over three to four months as muscle activity returns and the jaw gradually returns to its original shape. Unlike dermal fillers, there is no injection to dissolve Botox. Most patients choose regular top-up injections to maintain their slimmer jawline.
Who should avoid Masseter Botox?
Masseter Botox is not suitable if you are pregnant or breastfeeding, or if you have a condition affecting your nerves or muscles. It also will not work if a wide jaw is caused by bone shape rather than an enlarged muscle, which is why suitability is assessed at consultation.
Can I get Masseter Botox on the NHS?
No. Masseter Botox for jawline slimming is a cosmetic treatment, so it is not available on the NHS and is paid for privately. At PHI Clinic it starts from £595 per session, following a consultation with a doctor who will confirm whether the treatment is suitable for you.
Does Masseter Botox cause jowls?
No. Masseter Botox for jawline slimming is a cosmetic treatment, so it is not available on the NHS and is paid for privately. At PHI Clinic it starts from £595 per session, following a consultation with a doctor who will confirm whether the treatment is suitable for you.
Regulated, accredited and medically led
Masseter Botox is a prescription-only medicine in the UK, regulated by the Medicines and Healthcare products Regulatory Agency (MHRA). Prescribing and treatment at PHI Clinic is performed by GMC-registered doctors following in-person consultation.
PHI Clinic is CQC-registered for the regulated activities we provide, giving patients the assurance of independent inspection and oversight. Our Medical Director, Dr Tapan Patel, is a member of the British College of Aesthetic Medicine (BCAM) and an Inaugural Member of the Allergan Medical Institute (AMI), the manufacturer-led training and standards body for clinicians using Allergan products including Botox.
We do not provide unregulated cosmetic services. Every Masseter Botox treatment begins with a doctor consultation, prescription decision, and a clear treatment plan tailored to your face and medical history.
Why choose PHI Clinic for Masseter Botox
Our expertise enables us to offer advanced masseter Botox treatment in London. The PHI Clinic team is led by Dr Tapan Patel, holder of The Aesthetics Award 2023 for Outstanding Achievement in Medical Aesthetics, and a global trainer for Allergan Aesthetics, the manufacturer of Botox.
To ensure a consistent level of care, safety and effective results throughout, Dr Tapan has hand selected his notable team of experts. The team receive regular internal and external training by Tapan and leading global experts, making PHI Clinic the reputable Harley Street clinic that it is today. We are proud to have outstanding satisfaction rates with our masseter Botox patients. Patients feel more confident about their appearance and are delighted to have achieved such remarkable results in a quick, safe and minimally invasive way.
Your Masseter Botox practitioners
Masseter Botox near you in central London
PHI Clinic is located at our Harley Street clinic (102 Harley Street, London W1G 7JB), a five-minute walk from Oxford Circus and Great Portland Street, seven from Bond Street, and easily accessible from Marylebone, Mayfair, Baker Street, Fitzrovia and Regent's Park.
Opening Hours
| Monday & Tuesday | 9:30am – 6:00pm |
| Wednesday & Thursday | 9:30am – 8:00pm |
| Friday | 9:30am – 5:00pm |
| Saturday | 11:30am – 12:30pm |
| Sunday | Closed |
If you are considering masseter Botox treatment, the first step is a consultation with one of our registered practitioners. Call 020 7034 5999 or book online.
Masseter Botox frequently asked questions
Masseter Botox is a prescription-only medicine in the UK, regulated by the MHRA. At PHI Clinic it is prescribed and administered by GMC-registered doctors and NMC-registered nurse prescribers following an in-person consultation, and the clinic is CQC-registered for the regulated activities we provide.
Yes. Masseter Botox, jaw Botox, jawline slimming Botox and jaw reduction Botox all describe the same treatment: relaxing the masseter muscle so the lower face appears narrower. The names vary between clinics rather than the technique.
Yes. Masseter Botox is used in men to soften a heavy or square jaw, though the aim is usually a subtler change that keeps the jawline strong rather than tapered. Suitability is assessed in the same way at consultation.
Your treatment will be carried out by one of our GMC-registered doctors or NMC-registered nurse prescribers, each trained in Dr Tapan Patel's masseter technique. You will meet your practitioner at consultation, before any treatment is agreed.
Yes. Masseter Botox is often planned alongside other treatments as part of a wider assessment of facial balance. What suits you is discussed at consultation.
Botox is a purified form of botulinum toxin, injected in very small doses to temporarily relax a targeted muscle. This particular brand was first cleared for use by the Food and Drug Administration (FDA) in 1989, making it the world's first injectable approved to target wrinkles and fine lines.