How Many Units of Botox for Masseter? (and What It Costs)
Masseter Botox is priced by the unit, so "how much does it cost" and "how many units do I need" are the same question. Here is how injectors actually decide the dose, what a first treatment typically runs at Mirror Mirror, and why the number is different for jaw slimming than for TMJ.
Most adults need 20 to 30 units per side — 40 to 60 units total. First-timers usually start conservatively at 15–20 units per side; large or very strong masseters (common in men and heavy clenchers) can need 40–50 per side. At Mirror Mirror's rate of $14 per unit, a typical first treatment is $560–$840, and $13 per unit applies once you cross 50 units.
Where the Units Go
The masseter is the thick chewing muscle that runs from your cheekbone down to the angle of your jaw — clench your teeth and press just in front of your earlobe and you'll feel it bulge. It is one of the strongest muscles in the body for its size, which is exactly why it takes far more Botox than a forehead. Injectors place the product in the lower, bulkiest third of the muscle, usually at three points per side, staying well below the line of the cheekbone and behind the smile muscles to avoid affecting your expression.
Typical Masseter Dose by Goal
First treatment
Conservative dose to see how the muscle responds. Mild clenching, smaller jaw, or anyone new to it.
30–40 units total · $420–$560Jaw slimming
The range most adults land in for visible contour change and everyday clench relief.
40–60 units total · $560–$840TMJ & bruxism
Pain and grinding usually need a higher dose to meaningfully drop bite force. Temporalis sometimes added.
50–80 units total · $650–$1,040Large / male masseters
Hypertrophied muscle from years of clenching, or naturally larger male muscle mass.
80–100 units total · $1,040–$1,300Costs shown at Mirror Mirror's Botox rate: $14 per unit, $13 per unit at 50 units or more. Xeomin $13/unit. Your provider sets the actual dose at consultation; Mirror Mirror's masseter treatments typically run 20–40 units per side.
Four Things That Move the Dose
- Your goal. Cosmetic slimming needs enough to let the muscle shrink over time; TMJ pain or teeth grinding needs enough to cut bite force now — usually more.
- Muscle size and strength. Your injector feels the masseter while you clench. Years of grinding build a visibly bulkier muscle that needs more product.
- Sex. Male masseters are naturally larger and stronger and routinely need 10–15 more units per side.
- History. After several rounds the muscle stays smaller between treatments, and many clients need fewer units, less often.
Is 20 Units Enough? Is 10?
20 units total (10 per side) is a genuinely conservative starting point — fine for mild clenching or a first cosmetic try, but most people end up needing 20–30 per side to see a real change in contour or relief. 10 units total (5 per side) is generally too low for TMJ or bruxism; the masseter is too strong for that to meaningfully lower bite force, and most clinical protocols start higher. Under-dosing is the most common reason people say "masseter Botox didn't work for me." If your first treatment felt like nothing happened, the answer is usually a higher dose at the next visit, not a different treatment.
CostMasseter Botox Cost at Mirror Mirror
We price per unit, so you pay for exactly what is injected — nothing built into a flat "jaw package." Current rates in Los Angeles:
| Units (total) | Botox at $14/unit | At $13/unit (50+) | Who it fits |
|---|---|---|---|
| 30 units | $420 | — | Conservative first visit, mild clenching |
| 40 units | $560 | — | Typical starter, smaller jaw |
| 50 units | — | $650 | Standard slimming dose |
| 60 units | — | $780 | Standard slimming / mild TMJ |
| 80 units | — | $1,040 | TMJ, bruxism, larger masseters |
Repeat treatments run every 3–6 months. Members save 3–5% on every visit through the Membership & Loyalty Program, and Cherry financing is available.
TimelineWhat Happens After the Injection
Relaxation begins
Clenching eases; jaw feels looser. No visible change yet.
Full effect
Bite force drops. Morning jaw pain and tension headaches usually gone.
Slimming shows
The muscle begins to shrink from disuse; the lower face visibly narrows.
Peak contour
Maximum definition. Muscle starts to regain activity from month 4.
Repeat
Retreat as it fades. With consistency, intervals lengthen and doses drop.
What Can Go Wrong, and How Often
Common and temporary: soreness or a small bruise at the injection sites, mild headache for a day or two, and chewing fatigue with very hard or chewy food for the first week or two. Less common and technique-related: a slightly uneven smile if product diffuses forward into the muscles that lift the mouth, and a temporarily hollow look in the mid-cheek while the surrounding structures adapt to a smaller jaw muscle. In older clients or anyone with existing laxity, losing muscle volume can make jowls a touch more visible — which is why we sometimes pair masseter Botox with Forma. Severe complications are rare with an experienced injector who stays below the cheekbone line and behind the smile muscles.
Frequently Asked Questions
At Mirror Mirror, 30 units of Botox is $420 ($14 per unit). Nationally the same treatment ranges from about $300 to $600 depending on the city and the provider, with per-unit prices of $10–$20. Keep in mind 30 units total is a light masseter dose — 15 per side — and suits a conservative first visit or mild clenching. Most adults ultimately need 40–60 units, which at our rate is $560–$840.
40 units of Botox is $560 at Mirror Mirror. That is 20 units per side — the most common starting dose for jaw slimming and the low end of what TMJ treatment usually needs. Elsewhere in Los Angeles, 40 units typically runs $400–$800. If your provider recommends 50 or more units, our rate drops to $13 per unit.
Most adults need 20 to 30 units per side, 40 to 60 total, to relax the masseter enough that it gradually shrinks and the lower face narrows. Slimming shows around six weeks and peaks near three months. It only works if the square shape comes from an enlarged muscle — if your jaw width is bone, Botox won't change it. Your injector can tell which it is by feeling the muscle while you clench.
Yes, for the muscular kind. Botox in the masseter lowers how hard the muscle can contract, which breaks the clench-spasm-pain cycle, eases morning jaw soreness and tension headaches, and takes strain off the joint. Relief starts within 3–7 days and peaks at two weeks. It is not a fix for joint disc damage or arthritis, and treating bruxism this way is off-label, so it belongs with an experienced injector — often after a night guard has been tried first.
Three to six months, with some people getting up to nine. It tends to last longer than forehead Botox because the dose is higher. Strong chewers, heavy clenchers, and people with fast metabolisms clear it sooner. With regular treatments the muscle stays smaller between sessions, so many clients find they can stretch the interval and lower the dose over time.
Yes, completely. Once the Botox wears off the masseter regains full function, rebuilds its mass through normal chewing over the following months, and the jawline returns to its pre-treatment shape. Nothing about the treatment is permanent unless you keep it up — which is also why it is reversible if you decide the slimmer look isn't for you.
Get an Exact Unit Count
Your dose — and your price — is set in person after your injector feels the muscle. Book a complimentary consultation at Mirror Mirror Med Spa in Los Angeles.
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