Introduction To Jawline Slimming (Masseter Reduction)

The use of muscle relaxant injections (or anti-wrinkle injections) is not just reserved for the relaxation of lines of facial expression and wrinkles. A popular procedure is the use muscle relaxant injections to reduce the size of the masseter muscles of the jaw. This is a common and extremely effective treatment for teeth grinding, or bruxism.

Many people have hypertrophic masseter muscles, either as part of their normal anatomy or these muscles may be enlarged by excessive teeth grinding or clenching, known as bruxism. With overuse from habitual teeth grinding, the masseter muscles become larger and over developed. Over time this alters the shape of the lower face, creating a square jaw line.

Jawline slimming procedure by Dr Kate

People who suffer from bruxism often report daily headaches, ear and facial pain, worn down teeth and dental problems. They suffer from daily pain and discomfort which has previously only been treated with special splints and physiotherapy.  In addition, the overuse of the masseter muscles from chronic grinding results in hypertrophy of the muscles (enlargement of the muscle) which causes cosmetic deformities and an enlarged, square shape to the lower face which is often asymmetrical.

Masseter reduction or jawline slimming for both treatment of teeth grinding and also for the cosmetic purpose of slimming the lower face is a simple and effective procedure which is why it is so popular. This procedure involves the injection of wrinkle relaxers into the large masseter muscles to create a slim and more feminine jawline. The procedure works by relaxing (not paralysing) the muscle resulting in a softer and smaller appearance of the masseters and eventual atrophy (or shrinkage) over time.

The treatment can transform your face completely; many people go from having a square and masculine jaw to a narrow and oval face in a matter of weeks.

frequently asked questions


Muscle relaxant injections (the same product used as anti-wrinkle injections) is injected into the masseters on each side of the face and spread out at multiple points within the muscle to produce jaw reduction results. The amount of wrinkle relaxer used does vary but in general much larger amounts are needed when compared with treatment of wrinkles.

Face slimming and jawline reduction effect is seen at any time between 2 to 8 weeks.


Often a repeat treatment will need to be performed 4-8 weeks later to ensure the best results with follow-up in 6-12months.

Over time as the muscle atrophies less muscle relaxant is needed with longer periods between treatments. The results improve significantly over the first year of treatment. Often the vicious cycle of teeth grinding is broken after the first year of treatment and people find they no longer require high doses or ongoing treatments.


The masseters are two bulky muscles on each side of the angle of your jaw. They serve as muscles of mastication, which means they help you chew. A common concern with treatment of these muscles with muscle relaxants is that the muscle will freeze and you won’t be able to chew your food.

Given the large size of the muscle and the use of other smaller muscles of mastication, chewing is not affected by this treatment, although some people may report feeling a bit ‘funny’ chewing tough foods like steak immediately following treatment.


With any medical procedure there are always risks involved and your doctor will discuss all risks and contraindications prior to performing any procedure.

The procedure is highly effective, with minimal or no pain and absolutely no downtime at all. Minor side effects such as bruising and swelling to the injections points may be noted. A less common side effect is over treatment of the masseter muscles resulting in problems with chewing. This is minimised by correct dosing and placement of the muscle relaxing injections.

Muscle relaxant injections cannot be given in people with underlying neurological conditions such as Myasthena gravis and in pregnant or breastfeeding women.


Cosmetic Doctors

To view our up to date pricing with our Cosmetic Doctors, please visit our Medical Treatment Doctor Pricing page and look up under the Anti-Wrinkle Injections section.

Cosmetic Registered Nurses

To view our up to date pricing with our Cosmetic Registered Nurses, please visit our Medical Treatment Nurse Pricing page and look up under the Anti-Wrinkle Injections section.