Medically reviewed by Dr Tapan Patel
Last reviewed: 22nd February 2026
Introduction to Masseter Botox for jawline slimming
A wide, square jaw is often associated with a masculine face. Women with this facial anatomy may feel self-conscious and want a softer, slimmer, more feminine jawline. 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, reducing muscular activity and allowing the jaw to appear more refined. Over time, this can lead to muscle atrophy, creating a softer and more tapered silhouette without surgery.
PHI Clinic offers London’s best non-invasive procedure for jaw reduction using botulinum toxin A. This safe and comfortable treatment is performed by our highly skilled team on Harley Street, with safety and aftercare always at the forefront. You can also read our patient testimonials for real experiences and results from those who have chosen this jawline slimming treatment.
Masseter Botox for jawline slimming: what you need to know
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 to Expect from Your Jaw-Slimming Treatment
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.
Our expertise
Our unparalleled expertise enables us to offer the best masseter Botox treatments 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 incredible 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
Get slimmer jawline
Injecting Botox into the masseter muscle dramatically slims and softens a square jawline, reducing a heavy-set appearance and creating a more feminine look to the jaw. Masseter Botox treatment can also have physical benefits such as stopping the facial pain caused by teeth grinding.
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.
An overdeveloped masseter muscle can dramatically 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. The treatment takes around 20 minutes, and results last 3-4 months.
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. 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.
Patient satisfaction and safety are always our top priorities. We would only recommend a masseter Botox treatment when we feel it will deliver the excellent results our clients expect.
For patients suffering from persistent muscle tension in the jaw, Masseter Botox can offer long-term relief that extends beyond aesthetics. Many find that once the masseter is relaxed, their sleep quality improves, as night-time teeth grinding and clenching reduce. In some cases, even related facial swelling subsides, restoring a more streamlined profile and reducing morning jaw discomfort.
Safe and effective treatment
Your safety is our top priority and making our patients feel welcomed and reassured when entering PHI Clinic. To ensure maximum standard of patient care, all of our treatments are only ever carried out by our experienced and highly qualified team, who receive regular in-house and external training from industry experts.
At PHI Clinic we do not offer same day treatment as initial consultation to ensure patients have time to reflect on their bespoke treatment plan before choosing to proceed.
Masseter Botox frequently asked questions
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.
Masseter Botox injections cause the masseter muscle to relax and shrink over time. If this is your first treatment, you should expect to see results within 4-6 weeks.
Yes. Your speech should not be affected. Some patients experience a sensation of tiredness from heavy chewing of hard or tough foods. This may last a few weeks but typically subsides as the other muscles become stronger to compensate for the relaxing effect of Botox on the masseter muscle.
Masseter Botox is a temporary treatment and the results wear off naturally after a few months. If the treatment is not repeated, the original jaw shape will gradually return as masseter muscle activity returns to previous levels. Most patients wish to preserve their new, slimmer jawline, and continue to have top-up injections to maintain their results.
A wide jaw caused by an overactive masseter muscle is treatable with Botox, whereas a wide jawbone is not, and may require a more invasive procedure. Some people have a wide jawline due to a combination of bone shape and masseter muscle enlargement.
Our expert practitioners are able to assess each face and case individually at a consultation to determine whether or not masseter Botox is an appropriate treatment.
Dr Tapan Patel is one of the world’s leading practitioners of masseter Botox, and has also trained his specialist team of doctors and nurse injectors in his expert technique.
Side effects for masseter Botox treatment can include swelling and redness, due to the injectable nature of the treatment. This will be discussed with you at your initial patient consultation. Most patients report a reduction in swelling and redness within 24 hours.
If you have a medical condition that can affect safety, such as damaged nerves or muscle issues, it is important for you to disclose this information during your consultation to avoid any complications.
PHI Clinic does not offer Botox treatment to patients who are pregnant or breastfeeding. While there are no clinical studies to show that Botox is harmful to the baby or mother, medical professionals would not treat patients in these circumstances. Beyond these circumstances, there are no medical reasons for exclusion. The most important thing is to see a qualified practitioner, and be properly assessed for suitability.
Botox is a natural, purified form of the botulinum toxin, injected in a microscopic dose that is not poisonous. It temporarily relaxes the expressive facial muscles which cause fine lines and wrinkles. This particular brand of botulinum toxin 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. Botox is an established brand name and can also treat conditions like hyperhidrosis (excessive sweating).
After treatment, you are advised to avoid touching or massaging the injected area for at least six hours. You are also advised to avoid anything that causes excessive blood flow to the face, such as bending over for long periods of time, engaging in strenuous exercise for four hours afterwards, or going to steam baths or saunas. This ensures best results and avoids any small potential risk of the product migrating from the treated area. After six hours, you can clean the area, but we advise against applying any makeup until 24 hours after treatment to avoid potentially irritating the injection site.
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.
It is your primary chewing muscle, and it clenches your teeth together. Each time you chew food or clench your teeth, you are using your masseter muscle.
The procedure itself should be virtually painless, thanks to the skill and experience of all PHI Clinic practitioners. We use ultra-fine needles at PHI for maximum comfort, and the treatment is completed quickly. We describe the sensation of being injected with Botox as a slight scratch, lasting just a fraction of a second. It is extremely well tolerated by patients, and no local anaesthetic is required. There is no downtime after treatment.
Location
PHI Clinic
102 Harley Street,
London,
W1G 7JB,
United Kingdom
Tel: 02070345999
Opening Hours
Monday & Tuesday - 9:30am to 6:00pm
Wednesday & Thursday - 9:30am to 8:00pm
Friday - 9:30am to 5:00pm
Saturday - 11:30am to 12:30pm
Sunday - Closed
Opening times can change, if your appointment is outside of these times please contact the clinic for confirmation.
