What is Masseter Botox?

Masseter botox is an injection into the jaw muscles that slims a wide or square jawline and eases teeth grinding. Results develop over four to six weeks and last three to six months.

Masseter botox is an injection of botulinum toxin into the masseter muscles, the large muscles on either side of the jaw that you use for chewing. It relaxes those muscles, which gradually reduces their size and softens the appearance of the lower face. It’s used for two main reasons: to slim a wide or square jawline, and to ease the pain and tension caused by teeth grinding and jaw clenching (bruxism).

What is the masseter muscle, and why does it matter?

The masseter is one of the strongest muscles in the body relative to its size. It runs from your cheekbone down to your lower jaw and does most of the work when you chew. In some people, this muscle is naturally larger or thicker than average. In others, it becomes overdeveloped over time through habitual teeth grinding or clenching, often linked to stress.

When the masseter is significantly enlarged, it can give the lower face a square, wide, or angular shape. Some people like this look. Others find it bothers them, particularly those who’d prefer a more oval or tapered jawline. Masseter botox addresses this without surgery.

How does masseter botox work?

Botulinum toxin (botox) works by temporarily blocking the nerve signals that tell a muscle to contract. When injected into the masseter, it reduces the muscle’s ability to contract fully. Because the muscle is being used less intensively, it gradually reduces in size over the weeks following treatment, in the same way any underused muscle would.

The process is gradual rather than immediate. Most people start to notice the muscle relaxing within one to two weeks, with the slimming effect becoming more visible over the following four to six weeks as the muscle adapts. The full result is usually visible around six to eight weeks after treatment.

For teeth grinders, the reduced muscle activity also means less pressure on the jaw, the teeth, and the surrounding joints, which can significantly ease headaches and facial tension.

Who is masseter botox for?

Masseter botox suits a wide range of people. The main candidates are:

People who want a slimmer or more oval lower face and prefer a non-surgical approach
People with bruxism (teeth grinding) or jaw clenching, especially those who experience related headaches or jaw pain
People who have noticed their lower face becoming more square or prominent over time

It’s not a suitable treatment for those with certain neuromuscular conditions, and results are naturally more noticeable when the masseter is enlarged to begin with. A consultation with a qualified practitioner beforehand is always worth having to discuss whether it’s the right option for you.

What to expect: sessions, results, and downtime

The treatment itself is quick. A practitioner will mark the injection sites on the jaw, usually two to four points on each side, and administer small amounts of botulinum toxin into the muscle. The whole appointment takes around 20 to 30 minutes.

There’s minimal downtime. Some people experience mild tenderness or slight swelling at the injection sites for a day or two, but most go straight back to normal activities. You’re usually advised to avoid rubbing the area or doing intense exercise for 24 hours.

Results begin to show within one to two weeks and continue developing over the following month. The slimming effect is most visible at around six to eight weeks. How long masseter botox lasts depends on the individual, but most people find it holds for three to six months. With regular treatment, results often last longer as the muscle adapts.

How much does masseter botox cost?

Masseter botox typically costs between £200 and £400 in the UK, depending on the clinic, the practitioner’s experience, and the location. London clinics tend to sit at the higher end of that range. Because the treatment targets a functional muscle used for chewing, the dosing is usually higher than for cosmetic botox on the forehead or around the eyes, which is reflected in the price.

Frequently asked questions

How long does masseter botox last?

Most people find masseter botox lasts three to six months. With repeat treatments, the muscle often takes longer to return to its original size, so some people find they can extend the gap between sessions over time.

How long does masseter botox take to work?

You’ll typically start to feel the muscle relaxing within one to two weeks. The visible slimming of the jawline takes longer, usually becoming noticeable at four to six weeks and reaching its full effect at around eight weeks.

Does masseter botox cause jowls?

This is a common concern and worth addressing directly. When done correctly by an experienced injector, masseter botox shouldn’t cause jowling. The risk is higher if too much product is used or if it’s placed incorrectly, affecting the muscles responsible for facial support. Choosing a practitioner with specific experience in jaw botox reduces this risk significantly.

What are the side effects of masseter botox?

Side effects are generally mild. The most common are temporary tenderness and minor swelling at the injection sites. Some people notice a subtle change in chewing sensation, particularly when eating hard foods, though this settles as the body adjusts. Headache is occasionally reported in the first day or two. Serious complications are rare when the treatment is carried out by a qualified practitioner.

How much does masseter botox cost in the UK?

Expect to pay between £200 and £400 for masseter botox at a reputable UK clinic. Prices vary by location and practitioner level, with London typically at the higher end. It’s worth prioritising experience over price for this particular treatment, given the functional muscle involved.

Ready to find a qualified practitioner near you? Browse 580+ masseter botox clinics across the UK on Glowmi.