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The masseter muscle is a facial muscle that connects our lower jaw to our cheeks. It is one of the several muscles responsible for chewing. When this muscle becomes enlarged for a variety of reasons, usually in patients who grind or clench their teeth, it can dramatically change the shape of your lower face.

BOTOX or Botulinum Toxin A is a muscle relaxer. It’s use include to temporarily paralyses the muscle it’s injected into. Masseter Botox can also change your face shape and manage facial pain. Here we discuss about the MASSETER BOTOX treatment at our Harley Street, London Clinic along with its benefits and side effects. Non-surgical jaw reduction is a very popular treatment at our London Clinic.

What is masseter Botox?

Botox injections or Botulinum Toxin A in the masseter muscle will relax this facial muscle, and in turn shrink the jaw line (Jawline Slimming) and reduce the square appearance of the jawline.

Botox is generally solely associate with anti-wrinkle treatments. But it can help with a variety of conditions from hyperhidrosis to enlarged masseter muscle

The result of injecting botulinum toxin injection into the masseter muscle is that a square face will morph into a more V-shaped appearance. Injections of Botox in the masseter muscle are a safe, non-invasive method for jaw reduction and facial slimming, which can be performed in just a few minutes.

What is the masseter muscle?

The masseter muscle is located on each side of your jaw and is one of the main muscles involved with chewing. When someone chews or grinds their teeth too often, the masseter muscles can increase in size and cause issues with the shape of your face.

There most common reasons for increased size of the masseter muscles are:

  • Genetics
  • Ethnicity, with many patients from Asia having increased masseter muscles.
  • Clenching (bruxism), particularly at night
  • Grinding
  • Excessive chewing
  • Chewing on only one side of the mouth

What does Botox in the masseter muscle do?

Does it help TMJ?

If muscle tension contributes to your jaw pain, Botox can be a potential TMJ treatment. When Botox is injected into the chewing (masseter and temporalis) muscles can relax these muscles, helping to relieve TMJ pain. Botox injections are a reversible, non-surgical procedure that may be beneficial in treating TMJ disorder. Depending on the cause of your TMJ pain, this treatment can offer temporary but long-lasting relief.

Does Botox in masseter slim your face? (which cases yes, which cases not?

The masseter muscle can be reduced significantly using non-surgical treatment such as botulinum toxin — more commonly known as Botox. The procedure is non-invasive because it involves a series injections placed directly into the masseter muscle. The treatment is performed over several sessions with small doses of botulinum toxin until the masseter muscle has reduced down by degrees to the desired appearance. The number of sessions will depend on the individual’s reaction to the treatment. Most people may only need 1-2 sessions, others may need 3-4 sessions to achieve the desired results.

Jawline slimming with botox is not recommended for patients with a squared jaw line that is defined by squared jaw bones as botox only affects the jaw muscle.

Jaw Botox Before and After

The results of masseter Botox or Jawline Botox takes 4 to 6 weeks to show on average. Please note that the before & after results of masseter Botox treatment vary as each individual has different anatomy. The shape and size of the face and jawline is affected by the bone size, shape, soft tissue and the chin structure. The end result of facial slimming or jaw reduction can take up to four weeks to be evident.

How long does masseter Botox last?

Masseter Botox cal last 4-6 months after which it will slowly return to its original form. However with continued treatment of injecting botox the muscles to relax them will result in them gradually losing the grinding habit.

How can I make masseter Botox last longer?

Botox is great treatment for masseter muscle. However, the effects do wear off as it is naturally degraded by the body. You must understand You cannot make Botox last longer but you can help to extend the length of it’s effect. Here are some tips to help make Botox last longer.

  • Always use a highly experienced medical aesthetic practitioner in a medical setting. Botox injections require the correct + appropriate dosage and precise injection sites for maximum effectiveness.
  • For the first 24 hours, avoid strenuous exercise and excessive heat. Saunas, Hot Yoga, Strenuous exercising ( gentle exercise is fine) or intense facial massages can potentially cause the Botox to migrate to areas of your face it shouldn’t go. This can result in temporary facial paralysis, eyelid drooping, or other undesirable effects. It may help to sleep on your back in a slightly elevated position for the first night post-injection.
  • Avoid the Sun and Sunbeds.  Sun damage causes premature wrinkles. Botox is ineffective against these skin damaged wrinkles because they do not involve the underlying muscles. Always wear SPF on your face, neck, and hands every day. Maintain your results for longer by using a high quality broad-spectrum sunscreen and avoid the outdoors during peak UV hours.
  • Less Stress – Stress negatively affects your body in many ways, accelerates the ageing process and rapidly enhances common signs of ageing. To extend the benefits of your injections try to reduce unnecessary stress-inducers from your life while incorporating stress relief techniques like meditation or yoga into your day.
  • Zinc Supplements – Some studies have shown that the effects of Botox are linked to Zinc levels within the body. Many individuals tend to have a slight zinc deficiency. Regularly taking a zinc supplement after your Botox treatment might help to prolong the anti-aging effects.
  • Maintenance Treatments– The best way to extend the life of your Botox results is to undergo a maintenance treatments. Plan your appointments before your results wear off. Regular Botox treatments are especially useful as they will actually train targeted muscles to respond to the neurotoxin for longer periods of time. Don’t overdo it. Too many treatments too quickly can make your muscles resist Botox or react in other negative ways.


Before treatment the area will be cleansed and marked for injection. Typically, 15-50 units of botox is injected on each side of the face into the masseter muscle. This treatment should not have a major impact on biting or chewing. Patients who are interested in receiving botox to contour the jawline must be aware that the injection will only treat overactive masseter muscles and will not improve a squared jawline caused by bone structure.
The goal of jawline slimming is to reduce a prominent, disproportionate, or asymmetric jawline by weakening the masseter muscles with botox injections.

How long does masseter Botox take?

The masseter Botox treatment is a very quick procedure. It only takes 3 to 5 minutes to complete the full set of injections.

How to inject Botox into masseter muscle (incl. depths and size of needle)

Masseter muscle is very thick and bulky. Hence we use a slightly longer needle. 1ml syringe with a 20mm needle,  is the appropriate needle length. We mark the patients face with the areas we are going to inject. Then a longer needle is taken and injected into the muscle with almost the entire needle length.

Where to inject botox into the masseter?

The Botox injections are injected at a distance of 1.5 cm or more from the lower border of the mandible. The dose injected into one masseteric muscle is roughly 30units per one side. The number of injections to each mandible is four or five with 6iu per injection. The injections are placed in the belly of the masseter muscle.

How many injections for Botox in the masseter muscle?

This will vary from person to person as it would depend on the size of your jaw, severity of clenching and pre existing asymmetry being few of the deciding factors. The brand of Botox also has an effect of how many injections will be necessary.

How much Botox do you need for the masseter muscle? (Is 50 units a lot?)

Generally we inject 50 units of Botox, or 25 units on each side, directly into the masseter muscle. The effect of jawline Botox starts to be visible in a few days but the full effect takes up to two weeks.

Who does masseter Botox?

As with any procedure, it’s important to work with a qualified medical practitioner in a medical setting. This will reduce the risk of complications and achieve the results you want. At our clinic in London, Rupesh administers Botox masseter treatments.

How long does it take to see results?

It can take four to six weeks to see the results of Botox jaw slimming treatment. The masseter muscle is a relatively large muscle compared to the other muscles of the face hence takes longer to work. The patient may get symptomatic relief from the grinding early on, but the contouring effect may take a little longer to see as they rely on atrophy of the muscle.

How often should I do jaw Botox?

Jaw Botox should be ideally repeated every five to six months.


What to avoid after masseter Botox?

Avoid massaging you face or having facials for four hours after your Botox Masseter injections as well as remaining upright for four hours after the Botox Masseter injections. This will prevent any unwanted Botulism toxin affecting any other unwanted face muscle.

Avoid consuming alcohol for 3 days after Botox Masseter injections to minimise bruising

What to do after masseter Botox?

Masseter Botox Post-treatment advice include:

  • Stay upright for four hours.
  • Do not massage your face.
  • Do not consume alcohol for 3 days.

Can I sleep on my side after masseter Botox?

After four hours you can sleep on your side as it takes some time to settle. If you slept straightaway the Botulism toxin can migrate to other muscle and have an unwanted effect on them.

Is Botox in the jaw safe? Risks and side effects

What to expect after masseter Botox?

After the masseter Botox treatment, you can go immediately back to your usual activities. It doesn’t require any recovery time. However, you’ll need to avoid the following for the 24 hours:

  • rubbing the treated area
  • placing pressure on the treated area
  • exercise

These actions might spread the toxin to other parts of your face.

Does Botox in the masseter muscle hurt?

The Botox injection would feel like a tiny prick or like an ant bite. Most patients find the treatment very comfortable.

Can masseter Botox go wrong?

Masseter Botox is generally considered safe. However, it’s possible for the procedure to cause side effects such as:

  • pain or swelling at the site of injection
  • bruising
  • headache
  • flu-like symptoms
  • crooked smile
  • drooling

Does masseter Botox effect my smile?

Masseter Botox should not affect your smile as it does not target your smile muscles.

One of the side effects of the botox injection is unwanted diffusion to surrounding muscles and if this does occur to you smile muscle, it can cause a lopsided smile. This can be avoided by going to a medical clinic.

Does masseter Botox affect my chewing?

There may be a slight dull irritation when chewing after administering Botox to the masseter muscle. This only lasts a few days and should resolve within a week.

How do I know, if I need Botox for the masseter?

If you require slimmer, sharper V face without any surgical intervention then masseter Botox is for you especially if you have masseter hypertrophy (big Jaw muscles) and also asymetrical jaw/muscles.

Bruxism ( teeth grinding or teeth clenching) would benefit from Botox jaw slimming/masseter Botox.

Botox for jawline slimming is best for patients with enlarged jaw muscles caused by overuse of the masseter muscle.

How much is masseter Botox?

Masseter Botox cost varies depending on the amount injected into the masseter muscle and part of the country you are in. On average our price at our Harley Street, London clinic is £325 per treatment.

Does insurance cover masseter Botox?

We are a Private clinic in london and only accept direct payments. None of our treatments are covered by your insurance.

London Lip Clinic

At a glance.

Procedure Time: 30mins

Down Time: Usually None

Results Duration: 5 Months Plus

Risks: Bruising, Redness, Asymmetry, Infection, Crooked Smile, Drooling

Price: £325

London Lip Clinic

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If you’re looking for the best lip fillers in London, then contact the London Lip Clinic today for your FREE consultation and find out how Rupesh can give you the naturally plump, defined lips you’ve always dreamed of.


London Lip Clinic

8 Harley Street
London W1G 9QY
United Kingdom (UK)
Phone: 0203 239 7041
Additional phone number: 07956 576666


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