ProductsMy jaw aches when I wake up and my face looks wider than it used to. Masseter Botox can help with both, but they are two different problems that need different amounts. It is a small dose of botulinum toxin, a purified protein that tells an overactive muscle to relax, placed into the thick chewing muscle at the back of your jaw, the masseter.
I am Debra Jaliman, MD, a board-certified dermatologist on the Upper East Side, injecting Botox in New York City since 1992. I would rather tell you that you do not need treatment yet than sell you something. Nearly 10 million Botox-type treatments were performed in the United States in 2024, across every treatment area.
Which of these two people sounds like you?
Before anything is injected, I want to know which one you are, because the answer changes everything about the plan.
You clench, and it hurts
You want a softer lower face
What you notice
A sore jaw on waking, a dull ache at the temples, worn teeth, a night guard that keeps cracking
Your lower face has squared off over about ten years
Does it hurt
Usually, yes
Often not at all
Who spotted it first
Often your dentist
You did, in the mirror
What you want
To stop hurting
A softer shape
What I check first
How hard each side clenches, your dental history, and whether the cause is fixable first
Where the bulk sits, whether the two sides match, how it fits your lower face
What changes first
The morning soreness, in the first couple of weeks
Nothing visible at first. The change is slow and quiet
How I adjust
Lowest dose that calms the muscle, fine-tuned at two weeks
Build gradually over visits so the change stays natural
Plenty of people are both, and grinding and jaw-joint trouble commonly travel together. Grinding in your sleep, sometimes called bruxism, is common: a 2026 review in the Journal of Clinical Medicine puts night-time grinding at roughly one in five adults, with daytime clenching about as common. What matters is what is happening in your mouth, and we work that out from your symptoms and your dentist's notes.
Here is why your face changed. The masseter, one on each side of your jaw, is the muscle you chew and clench with. Work it hard enough and it gets bigger, the same way a bicep grows at the gym. The widening you see is muscle, not fat and not bone. Calm the muscle down and the jawline usually softens as it shrinks.
Why I match the amount to your muscle, not to a menu
A unit measures how much muscle-relaxing activity a dose carries, not how much liquid is in the syringe, and the units of one brand cannot be converted into the units of another. How many you need depends on how strong your masseter is, whether your two sides match, and whether you are here for comfort, shape, or both. Too few and the clenching comes back early. Too many and your smile can feel off or chewing gets harder.
Here, I put my hands on it. I feel your masseter on both sides while you clench, checking where it is thickest and whether one side is working harder. For jaw slimming, my published range is 25 to 50 units per side. For clenching alone the amount is usually lower, and I set it once I have felt how hard each side is working. I tell you the number I am using, and the fee is set by area rather than per unit. Our Botox treatment page lists the unit range for each area. I do every injection myself and record what I used and where, so your next visit starts from a record.
If a softer jaw is your only goal, I treat it as one part of your lower face. Our guide to Botox for jawline slimming and facial contouring covers the bigger picture.
What changes, and when
You will usually feel the relief before you see anything. Most of my patients notice the morning soreness easing within the first couple of weeks, well before the mirror looks any different.
The shape takes longer, and it arrives quietly rather than all at once. In a small 2025 pilot study of patients treated for jaw-muscle pain, ultrasound showed the muscle beginning to thin within about two weeks and continuing out to twelve weeks, with the pace slowing after the first month. That study followed only fifteen people and stopped measuring at twelve weeks. In my experience the effect starts to fade around three to four months for comfort, and often holds longer for the shape. After two or three rounds, many of my patients find the gap between visits stretches further, which is exactly what you want.
What can go wrong, told to you honestly
If the dose is too high or placed in the wrong spot, your smile can feel different for a while and tougher foods take more work. If one side is treated without accounting for the side you actually chew on, the result can look uneven. In my experience, years of heavy dosing can also leave the lower face looking hollow, because the muscle has been kept too small for too long. That is why I dose conservatively and record every placement.
Treating the masseter is an off-label use: the FDA-approved prescribing information for Botox does not list jaw clenching or slimming among its approved uses. Physicians perform it routinely, and you should have that fact up front.
I bring you back at two weeks to check how both sides settled. If one side needs a little more, I adjust it right then. Any touch-up you need in that window is included.
Before we treat, let's find out why you are clenching
Most clenching has a reason: stress, poor sleep, a bite problem, or a night guard that no longer fits. Botox calms the muscle but does not fix the cause. I would rather rule those things out first, because if the cause is fixable you may need less, not more.
If you are weighing a physician against other types of injectors, our guide on how to choose a Botox injector walks through what to look for.
What your first visit is actually like
It is a 30-minute consultation. I feel your masseter while you clench, go through your dental history and symptoms, and we agree on an amount before anything happens. If treatment is not the right first step, I will say so.
Request an appointment and we will work out which of the two problems you actually have.
FAQs
How much does masseter Botox cost in NYC?
Botox here is priced by area rather than by unit, and the exact figure is set at your consultation once we know what your muscle needs. The consultation is $250, credited toward your treatment if you decide to go ahead.
How many units of Botox go into the masseter?
For jaw slimming, my published range is 25 to 50 units per side. For clenching alone it is usually lower. The number depends on how strong your masseter is and whether both sides are working equally hard, which is why I feel the muscle before I decide.
Does masseter Botox hurt?
Most patients describe a quick pinch and a feeling of pressure rather than pain, and the injection takes a few seconds on each side. Bruising is possible and usually fades within a week. If needles are a concern, say so at the consultation and we will plan around it.
Is masseter Botox for teeth grinding or for jaw slimming?
It can do both, but they are different goals that call for different amounts. Clenching and grinding tend to ease first, within a couple of weeks. A softer shape follows gradually, with the biggest single change in the first two weeks and slower thinning out to about three months.
Does Botox for TMJ and jaw clenching actually work?
TMJ is short for the temporomandibular joint, the hinge where your jaw meets your skull. For many people the treatment relaxes the overworked muscle and eases morning ache and pressure within the first couple of weeks. It does not fix what is causing you to clench, so a dental check, sleep habits, and stress all still matter.
How long does masseter Botox last?
In my experience a round usually holds three to four months for comfort, and the softening often holds longer. After a few rounds, many of my patients go longer between visits.
Will masseter Botox change my smile?
It can if the dose is too high or placed poorly, which is exactly why I match the amount to your muscle rather than taking it from a menu. Tougher foods may also take more work for a few weeks at first. The two-week check is there to catch and adjust any of this.
Reviewed by Debra Jaliman, MD, board-certified dermatologist, New York City. Last updated: September 2026.
