People considering jaw slimming injections in Greater Vancouver tend to ask three things: how soon will my face look slimmer, how long will it last, and will my jaw bounce back bigger if I stop? Jaw slimming uses the same kind of neuromodulator as anti-wrinkle injections (botulinum toxin type A), placed into the masseter, the chewing muscle at the angle of the jaw. It addresses width that comes from muscle, and it does much less for width that comes from bone or fat. Below we cover onset, duration, what happens when you stop, and who it does not suit. For the treatment itself, see our anti-wrinkle and jaw slimming injections page. This guide draws on that page and on the general information in Canadian product monographs; your own plan is confirmed at consultation.
We do not name product brands here. In Canada these are prescription medicines, and your physician will tell you which product is used.
How long do jaw slimming injections take to work?
Think of it in two steps. The muscle starts to relax within a few days, and chewing may feel a little less forceful. A visibly slimmer lower face depends on the muscle gradually getting smaller, which takes weeks, and for most people the change becomes clear only after some time has passed. Larger, stronger masseters tend to show the change more clearly. Individual results vary.
Feeling that nothing has changed after the first week is normal. Relaxation and shrinkage are different processes: the first comes from the nerve signal being temporarily reduced and shows up within days, while the second is the muscle slowly getting smaller from doing less work.
A better way to track it than daily mirror checks: take front and both side photos in the same spot and the same light before treatment, then repeat every two weeks. Gradual change is easy to miss when you look every day.
Is my square jaw caused by muscle?
Not always. A wide lower face can come from a large masseter, from the shape of the jawbone itself, or from fullness in the lower cheeks, and often from a mix. Injections mainly help the muscle part. A quick self-check: clench your teeth and feel just in front of and below your earlobe. If a firm muscle bulges under your fingers, the masseter is likely contributing. Your physician confirms this at consultation.
Typical patterns:
- Muscle-driven: clear bulging on both sides when you clench, often with clenching, grinding, gum chewing or a liking for chewy food. This is where injections fit well.
- Bone-driven: the angle of the jaw flares out but the muscle does not bulge much. Injections change little, and your physician will say so.
- Fat or laxity: fullness in the lower cheeks or a soft jawline, where other approaches may suit better.
- Mixed: very common, and injections can be one part of a plan.
How long does jaw slimming last?
Our treatment page notes that the masseter typically lasts 4 to 6 months, a little longer than forehead or frown lines. Muscle strength, dose, chewing and clenching habits all affect it, so individual results vary. The effect fades gradually rather than switching off.
One common explanation for the longer duration is that once the muscle has become smaller, it takes time to rebuild its bulk, so the face changes back slowly even after the nerve signal has recovered. Some people find they can stretch the interval after regular treatment for a while, but this does not happen for everyone and should not be expected.
Will my jaw rebound or get bigger if I stop?
Generally, no. As the medicine wears off, the masseter regains strength and gradually returns towards its pre-treatment size, and your face shape follows. That is the effect ending, not a rebound. There is no evidence that stopping makes the muscle larger than it was before treatment.
A few things can make it feel as though the result came back quickly:
- Ongoing clenching or night-time grinding keeps the muscle working hard, which can speed up recovery.
- Diet: frequent gum chewing or tough, chewy foods.
- A conservative first dose, which may wear off sooner.
If you are worried about the result fading fast, talk with your physician about your chewing and clenching habits rather than simply topping up more often. If you grind at night, a dental assessment may also help.
What side effects can jaw slimming injections cause?
Common effects are small red marks at the injection points, occasional bruising, and chewing fatigue with tough foods for a while. Less common are an uneven smile, if the effect reaches a nearby smile muscle, or a hollowed look at the jaw angle. These are usually temporary and resolve as the medicine wears off. Difficulty swallowing, speaking or breathing needs medical care right away.
Two more points worth knowing in advance:
- If your face is already slim, a thinner masseter can leave the jaw angle looking hollow and can make lower-face laxity more visible. Your physician will usually be more conservative or suggest not treating.
- Chewing fatigue is usually most noticeable at first, and most people adapt. Mention any jaw joint pain or limited mouth opening before treatment.
What should I do after treatment?
- Stay upright for 4 hours and do not rub the sides of your jaw.
- For 24 hours, skip strenuous exercise, saunas and hot yoga.
- For 7 days, avoid facials, lasers and microcurrent over the area, and no contouring massage or gua sha tools.
- Go easy on very chewy foods for a while to limit chewing fatigue.
- Compare photos every two weeks rather than adding more product because week one looks the same.
Who should not have jaw slimming injections?
They are not suitable, or need a physician's assessment first, during pregnancy or breastfeeding, with infection or inflammation at the injection site, with a known allergy to botulinum toxin or its ingredients, with a neuromuscular condition such as myasthenia gravis, when the width comes mainly from bone or fat but a big change is expected, or when the face is already thin and the jaw angle is hollow.
If you have jaw joint problems, heavy night-time grinding or major dental work coming up, mention it at consultation. A dental assessment may be worth doing first.
How should I prepare for my appointment?
- Arrive without makeup so your physician can see your face shape and feel the muscle when you clench.
- Take front and side photos beforehand as a baseline.
- List your medications and supplements, such as aspirin or fish oil. Your physician decides whether anything changes; do not stop a medication on your own.
- Share any past jaw treatment: when, how long it lasted, and whether your smile was ever uneven.
- Describe your habits: night-time grinding, daytime clenching, gum chewing.
How does RAAC approach jaw slimming?
At RAAC, a medical team led by Dr. Charles Jiang, a licensed physician in British Columbia, first examines the masseter by touch, watches its shape when you clench and compares the two sides, to work out what is making the lower face wide. The dose is then set by muscle strength and your goal rather than sold as fixed unit packages, with a review if needed. Pricing is explained after consultation, and consultations are available in English, Mandarin and Cantonese.
The clinic is on No. 3 Road in Richmond, BC, a short walk from Lansdowne Station on the Canada Line.
Frequently asked questions
Is jaw slimming the same medicine as anti-wrinkle injections? It is the same class of medicine, a botulinum toxin type A neuromodulator. The difference is which muscle is treated and how much is used.
Can I have my jaw and frown lines treated at the same visit? Usually yes. Your physician plans the dose for each area together.
Can I still chew gum? Yes, but chewing less for a while helps with fatigue, and heavy gum chewing over time may help the muscle regain strength sooner.
Will it make my chin pointier? No. It narrows the jaw angle but does not change the length or shape of the chin.
Further reading
- Masseter injections and jawline slimming
- The RAAC guide to neuromodulators
- Comparing neuromodulator formulations
This article is for educational purposes only and does not constitute medical advice. Please consult with a qualified healthcare professional before undergoing any treatment.
