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The masseter muscle is a rectangular shaped muscle on the side of your face that is the strongest and largest muscle in your face. Overactivity of this muscle from grinding your teeth can lead to this muscle getting stronger and bulkier over time which can contribute to pain in the jaw, headaches and neck pain.

It can also lead to a wide lower face and a square appearance of the face. Some people genetically have very strong masseter muscles whilst others form them over time from grinding their teeth excessively, usually at night.

Anti wrinkle injections in this muscle can help relieve the pain from teeth grinding, also known as ‘bruxism’ and it can also help slim the jawline and lower part of the face.


Please read the FAQs below for more information about this treatment.

See Results


20 mins


6-9 months

no. of sessions



Very minimal


Please see our most commonly asked questions below

What kind of results can be achieved?
If you are suitable, we can usually eliminate most of the pain and slim down your lower face. If you are doing the treatment mainly for discomfort, we recommend using lower doses than we do for jawline slimming. This may be if you are already happy with the shape of your face. This treatment takes a bit longer to have a full effect than other areas of wrinkle relaxing injections and we usually recommend waiting 4 weeks till you see the full effect.
Who is this treatment suitable and not suitable for?
This treatment is usually only suitable if you have strong masseter muscles. When you clench your jaw and bite your teeth down, this muscle bulges out to the side. If you can feel this muscle clearly it is likely a strong muscle. The best thing to do is to come in for a consultation so we can assess it for you. If you do not have strong masseter muscles and still get the treatment done, you just won’t see much of a result in terms of jawline slimming. It is not harmful to get it. The degree of jawline slimming is dependent on your own individual anatomy, the size of the masseter muscle and the shape of your bone structure. People who have a wide bone structure may not see much of a difference with the jawline slimming. Often, you have to try the treatment once to see how much of an impact it can have for you. Whilst this treatment does help with pain from bruxism; we always recommend you also see a dentist to protect your teeth with a mouthguard. Teeth can get damaged significantly from excessive grinding. Allergies to Botulinum toxin are exceedingly rare. If you are pregnant or breastfeeding, you cannot have this treatment.
How long does it last?
On average Botulinum Toxin lasts 3-4 months but masseter anti wrinkle injections usually lasts 6-9 months. We generally recommend you try and do it every 9 months to minimise any potential side effects/risks. Please see section below. When Botulinum Toxin wears off, your muscle and face shape will return to how it was before. It should not look any different. It does take some time to return to how it was before. It is normal to start getting some movement in the muscle after a couple of months; this is completely normal as the return of muscle activity occurs gradually. This does not mean the wrinkle relaxing injections have worn off. Full return to activity takes 6-9 months.
What is the recovery/downtime?
You might have a tiny amount of redness in the area on the side of your face. Bruises are very rare. Most people socialise the same day.
What are the side effects and risks?
Like all medical treatments, there are side effects and risks. Mild bruising is common as are headaches and cold-like symptoms. Sometimes the result can be slightly asymmetrical, especially if you had some asymmetry to begin with. Complications are rare with this treatment. You may find you may not be able to smile fully as the muscles responsible for smiling may be affected. This usually resolves in a few weeks and is barely noticeable. We advise patients not to get this treatment done more frequently than 6-9 months because in our experience, weakening the masseter muscle too much can impact the tightness of the jawline. People, especially those over the age of 40 or with laxity of the skin can find that their jowls or double chin area is heavy after getting this treatment. If this does happen, it usually resolves but it requires your masseter muscle activity to return to normal which takes some time. Another rare side effect from getting this treatment too frequently (every 3 months) over a number of years (usually over 10 years) is that it can potentially weaken the bones and cause jaw fractures in the future. Although this is not an area that usually needs a top-up (unlike forehead anti wrinkle injections), we still recommend all new patients come for a review follow up appointment after 4 weeks to check the result for you and inject more at this point without any extra charge. We will then understand your anatomy better and will usually only need one appointment in the future. Therefore it is helpful to stick to the same injector who learns the special quirks about your face. It is important to follow the aftercare to minimise these risks and ensure you get the best result.
How painful is the treatment?
There is very minimal pain and hardly any patients require numbing cream. We use the tiniest needles available on the market. We recommend all patients take 1g of Paracetamol 1 hour before their appointment. We find patients sometimes find it a bit more painful around their menstrual cycle.
The appointment is 30 minutes long but the treatment itself is very quick, it usually takes 5 minutes. At your first appointment, we will spend a bit more time assessing your face and discussing the treatment.
No. of sessions
The desired results will usually be achieved with the first session, but new patients will often need to come for the follow-up appointment free of charge (for anti wrinkle injections only) at the 2-3 week mark.
How will I look straight after?
You may have a small amount of redness on the sides of your jaw. You may have a small bruise. Most people can go out and socialise the same evening. It takes 4 weeks for masseter wrinkle relaxing injections to kick in.
How is it done?
We initially undertake a thorough assessment of your whole face and check how it appears at rest and facial expression. We take photographs and then mark out the area to be treated. Numbing cream is usually not needed. We then use the tiniest needles available on the market. It will feel slightly cold as the liquid is injected into the sides of your jaw. There are normally 3-4 injections each side. It has the consistency of water. Most people say it feels like a pinch. The treatment is complete in 5 minutes.
Can it be reversed?
Wrinkle relaxing injections always wear off so no effect or even side effect is permanent. It is normal to start getting some movement around week 6-8, this does not mean it has worn off early. It is a normal return to activity but full activity takes 6-9 months. It is not possible to reverse wrinkle relaxing injections or remove it, so we advocate a lighter approach on your first sessions as it is possible to add more at your follow-up. However, if you do get a side effect such as asymmetry, it can often be improved by injecting more.
What is the aftercare?
We send a thorough aftercare email to all our patients but please find a summary below.

Looking after your wrinkle relaxing injections

1. Please do not apply any pressure to the areas treated for the first 24 hours. The anti wrinkle injections have been placed into specific muscles very carefully and pressure can dislodge it.

2. Please stay upright for the next 4 hours after treatment

3. No exercise for 24 hours and avoid very intense exercise for the next 3 days

4. Please be careful with wearing hats and caps for the first 24 hours as that can also apply pressure.

5. No facials or facial massages/devices for one week. No eyebrow treatments ideally for 2 weeks.
How many units do I need?
This is completely dependent on your own individual anatomy. A standard amount for the masseter is 50 units.
Which fillers do you use?
We use the original wrinkle relaxing injections brand in our clinic. It is more expensive than all other brands, but we feel it gives our patients the most reliable and long-lasting results.
How do I prepare before the appt?
Before your Appointment

1. Please stop using topical Retinols, Glycolic Acid, Lactic Acids, Salicylic Acid and Tretinoin 5 days before your treatment. This will minimise pain and bruising. However, if you have been established on these for a long time and your skin is likely to flare up without them, you do not need to stop them.

2. Please stop using any Vitamin E supplements and Ibuprofen/Neurofen 5 days before your treatment. Please do not stop any Aspirin prescribed by your GP.

3. Laser treatments for the face, microneedling and chemical peels have to be avoided 1 week before and after the treatment. Eyebrow treatments should be 2 weeks after wrinkle relaxing injections as their position may change slightly with treatment.

4. Please do not drink alcohol 24 hours before and after the procedure. You are slightly more likely to bruise with it.

5. Make sure you eat something before your appointment and are well hydrated. This prevents feeling light headed during the procedure.

6. It is advisable to take 1 g of Paracetamol (2 tablets) 30 mins-1 hour before your appointment as it will significantly reduce any discomfort during the procedure.

7. Please attend the appointment alone. There is limited space in the clinic and anybody with you will be asked to wait outside the building.

8. Please come to the appointment with makeup removed and minimal jewellery.

9. Please note, we are not able to carry out any Dermal Filler treatments if you are due to fly in the next 3 days. Wrinkle relaxing injections, Profhilo and Aqualyx are fine.
How does the pricing work?
There are different pricing structures. Please see price list for more information.


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