Also known as masseter injections, jaw slimming or facial slimming using muscle-relaxing injections is a minimally invasive procedure to produce a more feminine shape to the lower face. The square-jawed look – which is highly desirable for men – is usually the result of overly-developed masseter muscles. These are the muscles attached to the angle of your jaw and they control your chewing.

Women who tense these muscles or grind their teeth can find that they can become more pronounced, creating a wider, more masculine-appearing jawline. Teeth grinding, known as Bruxism, is typically involuntary and most patients aren’t even aware they are doing it. Asian women typically have a wider lower face than Caucasians due to the width of the jawbone, the thickness of the masseter muscle and underlying fat pads. Facial slimming with botulinum toxin has become an increasingly popular procedure for Asian patients.

Muscle-relaxing injections into the masseter muscle are a simple and effective non-surgical treatment for reducing the jawline, making your face look slimmer and more youthful. If you would like to know more about jaw slimming treatment, call our London clinic and we can arrange a consultation for you.

Quick Reference


10 - 15 minutes

Anaesthesia Used




Final Result

Can take 2 - 3 weeks to appear and results can last 3 - 4 months

FAQs for Jaw Slimming

Muscle-relaxing injections have been used for many years for both medical and aesthetic treatments and it has been rigorously tested for safety. Most patients are suitable for this treatment, although if you have a skin condition or any condition that affects the muscles or nerves, this may not be the appropriate treatment for you.

During your consultation, our consultant plastic surgeon Mr Mark Ho-Asjoe will take a full medical history as well as assess your facial shape and underlying muscular structure and then advise you whether this treatment will achieve the results you’re hoping for.

First, the neck and jawline are cleaned before a topical anaesthetic is applied to ease any discomfort that might be felt when the botulinum toxin is injected. The masseter muscles will then be marked and the botulinum toxin is then injected directly into the muscle. Mr Ho-Asjoe may make two or three tiny injections on each side.

Muscle-relaxing injections work by blocking the nerves that activate our muscles. Over a period of approximately a week, the muscles will relax and the face will gradually become slimmer and smoother over the following weeks.

If you suffer from Bruxism or teeth grinding, this treatment should also ease any symptoms you might be experiencing such as facial pain, headaches, pain and stiffness in the jaw, disrupted sleep or tooth sensitivity.

Muscle-relaxing injections are not permanent; the muscles will start to work normally again after four to six months and you will then require a repeat treatment. Regular treatments can mean longer-lasting results over time.

This is typically a very safe procedure with minimal downtime, although there may be some swelling, redness or bruising at the injection site immediately after treatment. There are some potential risks such as muscle weakness, but these should be temporary if experienced and this will all be discussed in full during your consultation.