What masseter BTX is
The masseter is the chewing muscle at the angle of the jaw. When it is large, the lower face can look wide or square. Botulinum toxin is a prescription medicine. It blocks the signal from nerve to muscle, so the muscle contracts less and shrinks through disuse.
This is a medical treatment and must be given by a registered doctor. Units are specific to each product and cannot be swapped between brands. The right dose comes from examining your own muscle.
Masseter BTX in Singapore: the short answer
If your jaw has a firm bulge when you clench, muscle may be the cause, and BTX may help. If the width comes from bone, fat or loose skin, it will not. See the masseter treatment page. For the difference between relaxing a muscle and adding support, see botulinum toxin vs fillers.
Who it tends to suit
A firm bulge at the jaw angle, confirmed by the clench test.
A wide lower face linked to clenching or night-time grinding, with or without wanting a slimmer outline.
Where muscle and not bone is the cause.
You accept that any change is gradual, varies from person to person and fades with time.
How the muscle is assessed
What happens at treatment
It is a short in-clinic procedure. A few small injections go into the lower part of the muscle on each side. The first dose is conservative and is matched to muscle bulk, then reviewed at two weeks. Ordinary activity can usually continue straight away. On the first evening, avoid rubbing or massaging the jaw, lying face-down, heavy exercise and alcohol. There is no immediate visible change. Chewing may feel weaker for some days, and any change in the lower face is slow, over several weeks. Mild muscle ache, small bruises and heaviness on tough food are normal early on. Review checks symmetry and any residual bulge. The product is named at the time of treatment, so ask if you are unsure what was used.
Clenching and grinding
Bruxism is grinding or clenching. Masseter overuse is linked to morning jaw ache, tension headache, tooth wear and strain on the jaw joint. BTX lowers the force the muscle can produce, which can reduce the load while it is active. It does not cure bruxism or treat causes such as stress, sleep or airway problems. It does not replace a night guard, and dental review sits alongside treatment. The aim can be bruxism, slimming or both, and the plan differs with each.
Who should avoid it or wait
Pregnancy or breastfeeding, active infection or skin disease at the injection sites, or a known allergy to the product.
Myasthenia gravis or Lambert-Eaton syndrome are assessed carefully and are often declined.
Aminoglycoside antibiotics and others that affect nerve-to-muscle signals need review. Blood thinners call for caution.
Over-treatment can make the cheeks look hollow, and lax skin may look less supported once the muscle is smaller.
What it cannot do
| Concern | Why BTX does not help | Option to assess |
|---|---|---|
| Wide jaw from bone | It has no effect on bone | Surgical assessment |
| Cheek fat | Buccal fat sits higher and further forward | Face slimming guide |
| Loose skin | It does not tighten | Jowls treatment or HIFU |
| Weak chin or no V shape | It adds no projection | Chin enhancement |
Risks to discuss first
What published data show
Published reports describe paradoxical bulging as the most common of these events. That is a reason to keep your review appointment and to report concerns, even when they seem small. Units also differ between products, so doses cannot be compared across formulations. No published figure can tell you how much your own face will change.
How long it lasts and how fees work
The effect is temporary, lasting roughly a few months. The muscle can rebuild as the nerve recovers, especially if clenching continues. Repeat timing is set at review and is not booked in advance. Cost depends on masseter thickness on each side, the product and amount, whether one or both sides need treatment, whether the aim is slimming, bruxism or both, and any combined treatment. A written quote is given after examination, and the consultation also decides whether treatment is advised at all.