Masseter Botox is a treatment that uses botulinum toxin type A injections in the masseter muscle, which is the large chewing muscle at the side of the jaw. It is often used when this muscle is enlarged, overactive, or contributing to a wider lower face.
Masseter Botox may help reduce jaw muscle size, soften a square-looking jawline, and improve symptoms linked to jaw clenching or bruxism in some people. The effect is temporary and depends on the dose, injection technique, muscle size, and whether repeat sessions are needed.
Although the procedure is usually quick, it should be done by a trained health professional with good knowledge of facial anatomy. Possible side effects include chewing weakness, facial asymmetry, jaw discomfort, and, in rare cases, unwanted changes in nearby muscles or bone with repeated use.
How masseter Botox works
Botulinum toxin type A works by blocking nerve signals that tell the masseter muscle to contract. When the muscle contracts less strongly, it gradually becomes less active.
Over time, this can reduce muscle thickness and make the lower face look slimmer in people with masseter muscle enlargement. It may also lower the force of clenching or grinding in people with bruxism, which can help reduce muscle pain and tension in some cases.
The results are not immediate because the muscle needs time to respond to the reduced activity. The effect also wears off over time, so repeat treatment may be needed to maintain the result.
Benefits of masseter Botox
Masseter Botox may be recommended for aesthetic or functional reasons, depending on the person’s symptoms and goals.
1. Facial slimming
One of the main uses of masseter Botox is to reduce a wide or square-looking lower face caused by large masseter muscles. Studies using facial measurements, ultrasound, CT scans, and 3D imaging have found that botulinum toxin type A can reduce masseter thickness and improve lower-face contour.
This effect is most noticeable when the jaw width is mainly caused by muscle size rather than bone structure. If the jaw shape is mostly due to bone, Botox may have a more limited effect.
2. Masseter hypertrophy
Masseter hypertrophy is enlargement of the masseter muscle. It can happen on one or both sides of the face and may make the jaw look wider or uneven.
Botulinum toxin type A can be used as a nonsurgical option for reducing masseter muscle size. In some cases, it may be considered as an alternative to more invasive treatments.
3. Bruxism and jaw tension
Masseter Botox may help some people with bruxism, which is teeth grinding or jaw clenching. By weakening the masseter muscle, the treatment may reduce bite force, jaw muscle activity, and pain related to overuse of the muscle.
However, it does not treat every possible cause of bruxism. A dentist or doctor may also need to check for tooth damage, temporomandibular joint problems, stress-related clenching, or other contributing factors.
How masseter Botox is done
Masseter Botox is done by injecting small amounts of botulinum toxin type A directly into the masseter muscle. The health professional usually checks the muscle by asking the person to clench the jaw, which makes the masseter easier to feel.
The injections are placed in specific areas of the muscle to reduce the risk of affecting nearby structures. Some techniques use several injection points, such as a 3-point or 6-point pattern, depending on the anatomy, muscle size, and treatment goal.
Knowledge of the masseter muscle, nearby nerves, and safe injection zones is important. In some cases, imaging methods such as ultrasound may be used to help guide placement, especially when anatomy is more complex or when there is a risk of uneven results.
The amount used can vary from person to person. It should be individualized based on muscle thickness, facial shape, symptoms, previous response to treatment, and the product being used.
What to expect after masseter Botox
After masseter Botox, the treated muscle gradually becomes weaker. This can lead to a slower reduction in jaw muscle size and lower-face width.
Some people may notice changes in chewing strength, especially when eating tough foods. This effect is usually related to the way botulinum toxin reduces muscle activity.
Results are temporary. The effect can fade as nerve signaling returns and the muscle becomes active again. Repeat injections may maintain the effect, but repeated treatments should be planned carefully because studies have reported changes in bite force, muscle volume, and, in some cases, bone volume around the jaw angle.
Possible side effects
Masseter Botox is generally considered a minimally invasive procedure, but side effects can occur.
Possible side effects include:
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Pain, swelling, or bruising at the injection site
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Chewing weakness
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Jaw fatigue, especially when eating hard foods
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Facial asymmetry
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Uneven smile
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Paradoxical masseter bulging, which is a temporary bulge in part of the muscle
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Temporary changes in bite force
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Unwanted spread of the toxin to nearby muscles
Repeated injections may increase the risk of longer-lasting changes in the masseter muscle. Some studies have also reported possible changes in the jawbone area after repeated treatment, although more research is needed to understand the long-term importance of this finding.
A medical assessment is important if there is severe weakness, trouble swallowing, trouble speaking, breathing difficulty, or signs of an allergic reaction after treatment.
Contraindications
Masseter Botox may not be suitable for everyone. It is usually not recommended for people with an infection at the injection site or a known allergy to botulinum toxin products.
It may also be contraindicated or require extra caution in people with certain neuromuscular disorders, because these conditions can increase the risk of excessive muscle weakness. Pregnancy and breastfeeding are also commonly listed as situations where treatment should be avoided or delayed unless a qualified health professional considers it appropriate.
Masseter Botox should only be done after a proper evaluation by a trained professional. This helps confirm whether the jaw shape or symptoms are related to the masseter muscle and whether botulinum toxin is an appropriate option.