Medical Treatments · Fillers & Injectables · IN Eternity Clinic
Jaw Slimming Injections in Singapore
When a square lower face comes from a strong chewing muscle, a carefully dosed neuromodulator can relax and gradually slim it. The first step is working out whether muscle is the cause at all.
Written & medically reviewed by Dr Sin Yong · 8 October 2026
Quick answer
- When a square lower face comes from a strong chewing muscle, a carefully dosed neuromodulator can relax and gradually slim it. The first step is working out whether muscle is the cause at all.
- Used for: Wide Jaw & Square Face.
- Performed by: Dr Sin Yong at IN Eternity Clinic, 9 Scotts Road, Pacific Plaza (beside Orchard MRT).
- Enquire: SkinRev Lab, CityLink Mall (City Hall MRT) passes enquiries to the clinic, or contact IN Eternity Clinic directly on +65 8815 3008.
- Suitability, number of sessions and pricing are decided at consultation; individual results vary.
Jaw slimming injections use a neuromodulator to relax the masseter, the thick chewing muscle at the angle of the jaw. If you are searching for jaw slimming in Singapore, the most important point is that a wide or square lower face can come from muscle, bone, fat, the parotid glands or a mix. Injections only help the muscle part. At IN Eternity Clinic, Dr Sin Yong assesses which is responsible before suggesting treatment.
A prominent masseter is common in East Asian faces and can be made larger by clenching, grinding or chewing habits. When the muscle is relaxed, it is used less and gradually becomes thinner, so the lower face looks softer and more tapered, often described as a V-shape. The change is gradual over weeks and is temporary: as the muscle recovers, it can regain bulk, so treatment is repeated if you want to keep the effect. It is a medical procedure with real side effects, which careful dosing and placement help to reduce.
How it works
The mechanism,
in plain English
Muscles contract when a nerve releases a chemical messenger, acetylcholine, at the junction between nerve and muscle. A neuromodulator blocks that release in the injected area, so the muscle receives a weaker signal and contracts less forcefully. Facial expression is not affected when the injections stay within the masseter, but the muscle does far less work.
A muscle that is used less becomes thinner, a process called disuse atrophy. In the masseter, this usually begins to show two to four weeks after injection and continues over the following weeks, which is why the slimming effect appears gradually rather than straight away. Ultrasound studies have measured clear reductions in masseter thickness after treatment.
Over the following months, the nerve endings form new connections and the muscle slowly regains strength and some bulk. Placement matters: the masseter has a safe central zone, and injecting too close to its front edge or too superficially can affect nearby smile muscles, causing an uneven smile. Dr Sin Yong maps the muscle by palpation while you clench before injecting.
“Relaxing a muscle can slim a jaw that is wide because of muscle — it cannot change bone, remove fat or tighten sagging skin.”
— Dr Sin Yong, IN Eternity Clinic
- Energy / product
- Neuromodulator injection (wrinkle-relaxing injection) into the masseter muscle
- Target layer
- Masseter muscle at the angle of the jaw
- Typical session
- About 15–20 minutes, including assessment and marking
- Downtime
- Usually minimal — small bumps or occasional bruising at injection points for a day or two
- Performed by
- Dr Sin Yong, IN Eternity Clinic
Is it right for you
Who it suits,
and who it does not
Jaw slimming injections usually suit adults whose lower face is wide mainly because of a strong masseter muscle — you can feel the muscle bulge firmly at the angle of the jaw when you clench. They suit people who want a softer, more tapered jawline without surgery, those whose masseters have enlarged from clenching or grinding, and people with one side larger than the other where muscle is the cause. They also work well as part of a wider lower-face plan that may include chin filler for projection.
Jaw slimming injections are not suitable during pregnancy or breastfeeding, for people with neuromuscular conditions such as myasthenia gravis, with infection at the injection site, or with a known allergy to the product. Tell the doctor about medicines such as certain antibiotics that can interact, and about jaw-joint problems. If width comes mainly from bone, fat or enlarged salivary glands, injections will not help much. In people with thin cheeks or early lower-face laxity, slimming the masseter can make hollows or jowls look more noticeable, so a different plan may be better. Teeth grinding is a dental and medical issue that may need a dentist's input as well.
What to expect
Consultation, session
and aftercare
Treatment starts with a consultation at IN Eternity Clinic. Dr Sin Yong examines the lower face at rest and while you clench, feels the muscle borders, and checks for fat, bone shape, gland enlargement and skin laxity. He explains what proportion of the width is muscle and what change is realistic. Photographs are taken at fixed angles for comparison. A course is usually planned at consultation, with a review to judge the effect and decide on future timing and dose.
The injections themselves take a few minutes. A fine needle places small amounts at several points within each masseter; most people feel brief pricks and pressure. You can return to normal activities straight away. For the rest of the day, avoid massaging the area, lying flat for a few hours, saunas and strenuous exercise. Chewing may feel slightly weaker or tire more easily for a few weeks, especially with tough foods, and slimming becomes visible gradually from around two to four weeks.
Where this happens
Assessment and non-invasive care — SkinRev Lab, CityLink Mall #B1-28, 1 Raffles Link, Singapore 039393. Underground from City Hall MRT and Esplanade MRT; a short walk from Raffles Place, Marina Bay, Suntec and Bugis. Open daily 11am–8pm.
Medical treatment — IN Eternity Clinic, 9 Scotts Road, #12-01 Pacific Plaza, Singapore 228210, beside Orchard MRT (three stops from City Hall on the North-South line). Mon–Sat 11am–8pm, closed Sunday. Treatments are performed by Dr Sin Yong. WhatsApp +65 8815 3008.
Enquiries to SkinRev Lab about medical treatments are passed to IN Eternity Clinic, where Dr Sin Yong performs them.
What the research says
The evidence,
with sources
The strongest evidence now comes from a 2026 systematic review and meta-analysis of five randomised, placebo-controlled studies with 536 participants. It found that neuromodulator injection improved masseter prominence scores, reduced muscle thickness and increased satisfaction compared with placebo in the short term, but noted substantial variation between studies and that the ideal dose and protocol remain undefined. Earlier, a large Korean clinical series of over 1,000 treatments used ultrasound to measure masseter thickness and found the muscle thinned noticeably by three months, with the atrophic effect beginning two to four weeks after injection.
Side effects are usually temporary. A literature review of 36 studies found that most complications, such as chewing weakness, smile asymmetry or bulging, appeared within two to four weeks and resolved within about 12 weeks. A 2024 meta-analysis on mandibular bone found a small reduction in the thickness of the outer cortical bone in humans after injections, without clear changes in bone volume or density, and called for longer studies of repeated treatment. This supports careful dosing and sensible intervals rather than frequent repeat injections.
References
- Machado GF, De Freitas LR, Ribeiro LFS, et al. Efficacy of botulinum toxin for masseter muscle hypertrophy: a systematic review and meta-analysis. J Plast Reconstr Aesthet Surg. 2026;119:212-225.
- Kim NH, Chung JH, Park RH, et al. The use of botulinum toxin type A in aesthetic mandibular contouring. Plast Reconstr Surg. 2005;115(3):919-930.
- Yeh YT, Peng JH, Peng HP. Literature review of the adverse events associated with botulinum toxin injection for the masseter muscle hypertrophy. J Cosmet Dermatol. 2018;17(5):675-687.
- Moussa MS, Bachour D, Komarova SV. Adverse effect of botulinum toxin-A injections on mandibular bone: a systematic review and meta-analysis. J Oral Rehabil. 2024;51(2):404-415.
Common questions
Your questions,
answered
How much does jaw slimming in Singapore cost?
Pricing for jaw slimming injections is given at consultation at IN Eternity Clinic. The amount needed depends on the size and strength of your masseters, whether both sides are similar, and how much change you want. Dr Sin Yong explains the dose plan and fees after examining you, and will tell you if the width is mainly bone or fat, in which case injections may not be worth doing.
How do I know if my wide jaw is muscle or bone?
Place your fingers at the angle of your jaw and clench your teeth. If a firm bulge pushes outwards, the masseter is contributing. If the width stays the same and feels hard and bony at rest, the jaw shape itself is the main reason. Fat and enlarged salivary glands feel different again. A doctor's examination, sometimes with ultrasound, gives a clearer answer before any treatment.
When will I see jaw slimming results?
Nothing changes in the mirror for the first week or two, because the muscle needs to be used less before it thins. Slimming usually becomes visible from around two to four weeks and continues over the following weeks. The effect is temporary, as the muscle gradually regains strength over months. Timing of further treatment is decided at review rather than on a fixed schedule.
Will it affect my chewing or my smile?
Chewing tough or chewy food may feel weaker or tire faster for a few weeks; most people adapt quickly. If the product spreads to nearby smile muscles, the smile can look uneven for a while, which is why accurate placement within the safe zone of the masseter matters. Published reviews find that most such effects appear within a few weeks and resolve within about three months.
Can jaw slimming in Singapore help teeth grinding?
Relaxing the masseter reduces how hard the jaw can clench, and it is sometimes used off-label when grinding or clenching contributes to an enlarged muscle. It does not treat the underlying causes of grinding, and it does not replace a night guard or dental care. If you grind your teeth, Dr Sin Yong may suggest you also see your dentist so the problem is managed properly.
Is jaw slimming safe long term?
For most people, side effects are temporary. Research on the jawbone suggests a small change in the thickness of the outer bone layer after injections, without clear loss of overall bone volume or density, and longer studies of repeated treatment are still needed. This is one reason Dr Sin Yong uses considered doses and sensible intervals, and reviews the plan rather than repeating treatment automatically.
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