Masseter Botox: Complete Guide to Jaw Slimming, TMJ & Bruxism Treatment, Units, Cost & Results (2026)

What Is Masseter Botox?

Masseter Botox is the injection of botulinum toxin (Botox, Dysport, or Xeomin) directly into the masseter muscles — the large, powerful jaw muscles on each side of your face that control chewing and clenching. It serves two distinct purposes:

Cosmetic (Jaw Slimming): Reduces the size of enlarged masseter muscles to create a slimmer, more contoured, V-shaped jawline
Therapeutic (TMJ/Bruxism): Relaxes overactive jaw muscles to relieve TMJ pain, teeth grinding (bruxism), and jaw clenching

The masseter is one of the strongest muscles in the body — capable of generating up to 200 pounds of force on the molars. In some people, this muscle becomes enlarged (hypertrophied) from habitual clenching, grinding, or genetics, creating a wide, square jawline. Botox relaxes the muscle, causing it to gradually shrink over 4-8 weeks while retaining enough function for normal chewing.

                    Dual Benefit: One of the unique advantages of masseter Botox is that patients seeking jaw slimming often also get relief from TMJ symptoms they didn't know were related — and vice versa. The same treatment addresses both cosmetic and functional concerns simultaneously.
                

Cosmetic vs. Therapeutic: Two Reasons, One Treatment

Cosmetic: Jaw Slimming

Slims a wide, square jawline into a V-shape
Creates more feminine or balanced facial proportions
Reduces the appearance of a "boxy" lower face
Popular in K-beauty and Asian aesthetics for V-line jaw
Softens angular jaw contours
Non-surgical alternative to jaw reduction surgery
Results develop gradually over 4-8 weeks
Not covered by insurance

Therapeutic: TMJ & Bruxism

Relieves TMJ (temporomandibular joint) pain
Stops or reduces teeth grinding (bruxism)
Reduces jaw clenching force and tension
Alleviates associated headaches and migraines
Protects teeth from grinding damage
Alternative to night guards and splints
Relief begins within 1-2 weeks
May be covered by medical insurance (off-label)

How Masseter Botox Works

Understanding the anatomy of the masseter muscle helps explain why Botox is so effective for both jaw slimming and TMJ relief.

Masseter Muscle Anatomy

The masseter is a thick, rectangular muscle that runs from the zygomatic arch (cheekbone) to the angle and ramus of the mandible (jawbone). It has two layers:

Layer	Location	Function	Botox Target
Superficial masseter	Outer layer, easily palpable	Primary jaw closing, face width	✔ Primary injection target
Deep masseter	Inner layer, closer to bone	Fine jaw movements, stabilization	Sometimes targeted in severe cases

The Mechanism: From Injection to Slimming

Botox works by blocking the release of acetylcholine at the neuromuscular junction, preventing the nerve signal from reaching the muscle. Here's the cascade:

Botox injected into the masseter muscle belly
Acetylcholine blocked within 24-72 hours — muscle can no longer contract at full force
Muscle relaxation begins — clenching force reduces by 20-40%
Disuse atrophy — without full contraction, the muscle gradually shrinks (like a muscle you stop exercising)
Jaw slims — visible narrowing of the lower face as the muscle mass decreases

                    Why Masseter Botox Lasts Longer: The masseter is a much larger muscle than the frontalis (forehead) or orbicularis oculi (crow's feet). Because of this, the muscle takes longer to recover from Botox-induced atrophy, meaning masseter Botox typically lasts 4-6 months vs. 3-4 months for cosmetic facial Botox. With repeated treatments, results can last even longer as the muscle progressively reduces in size.
                

How Many Units of Botox for the Masseter

Dosing for masseter Botox is significantly higher than cosmetic facial Botox because the masseter is a much larger, stronger muscle. Here's the dosing guide:

Patient Profile	Units Per Side	Total Units	When Used
First-time / Mild hypertrophy	25-30 units	50-60 total	New patients, mild jaw widening, light bruxism
Moderate hypertrophy	30-40 units	60-80 total	Visible square jaw, moderate grinding, TMJ pain
Severe hypertrophy	40-50 units	80-100 total	Very large masseter, severe bruxism, significant TMJ
Touch-up (repeat patient)	20-30 units	40-60 total	Maintaining results from previous sessions

Dosing Comparison: Masseter vs. Other Areas

Treatment Area	Typical Units (Botox)	Muscle Size
Masseter (per side)	25-50 units	Very large
Forehead (frontalis)	10-30 units	Medium
Glabella ("11 lines")	20-25 units	Small
Crow's feet (per side)	8-15 units	Small
Lip flip	4-8 units	Very small

Dysport vs. Botox Units: If your provider uses Dysport instead of Botox, the unit count will be approximately 2.5-3x higher (e.g., 75-150 Dysport units per side vs. 25-50 Botox units). This is because Dysport units are smaller, not because you're getting more product. The cost and effect are comparable. See our Dysport guide for conversion details.

The Procedure: What to Expect

Masseter Botox is one of the quickest and most straightforward aesthetic procedures. The entire appointment typically takes 15-20 minutes, with the injections themselves taking only 5-10 minutes.

1

Consultation

Provider assesses jaw, checks bite, asks about clenching habits

2

Clench Test

You clench your jaw so provider can feel the masseter size and mark injection points

3

Injection

3-5 injection points per side into the muscle belly using a fine 30-gauge needle

4

Massage

Brief gentle pressure to distribute Botox evenly within the muscle

5

Done

No downtime — return to normal activities immediately

Injection Point Placement

The injections are placed in the lower portion of the masseter muscle belly, away from critical structures. Here's why placement matters:

3-5

Points Per Side

Distributed across the lower 2/3 of the muscle belly

1 cm

Above Jawline

Injected at least 1 cm above the mandible border

0

Near Parotid

Kept away from the parotid gland and facial nerve

30G

Needle Size

Ultra-fine needle minimizes discomfort and bruising

Results Timeline & Before/After Expectations

Masseter Botox results develop in two phases: functional improvement (reduced clenching) happens within days, while visible slimming takes weeks as the muscle atrophies.

Day 1-3: Onset of Action

Botox begins blocking nerve signals. You may notice slightly less jaw tension when you clench. No visible change yet.

Week 1-2: Functional Improvement

Reduced clenching force becomes noticeable. TMJ pain begins to ease. You may feel your jaw is "weaker" when chewing tough foods. Still no visible slimming.

Week 3-4: Early Slimming

The masseter muscle begins to visibly reduce in size. Your jaw may start to feel narrower. Bruxism patients notice less morning jaw soreness and fewer headaches.

Week 6-8: Peak Slimming

Maximum muscle atrophy — this is when jaw slimming is most visible. The lower face appears noticeably slimmer and more contoured. This is the "money shot" for before/after photos.

Month 3-4: Sustained Results

Full Botox effect maintained. Jaw remains slim. TMJ/bruxism relief continues. This is typically the longest-lasting phase.

Month 4-6: Gradual Return

Botox begins to wear off. Muscle function gradually returns. Jaw slimming slowly diminishes. This is the ideal time for your next session to maintain results.

                    Cumulative Effect: With each subsequent treatment, results tend to last longer and require fewer units. After 3-4 treatment cycles (12-18 months), many patients can extend their treatment intervals to every 6-9 months because the masseter muscle has been "retrained" to a smaller size.
                

Botox for TMJ & Bruxism (Teeth Grinding)

Botox for TMJ and bruxism is one of the most effective non-surgical treatments available, with studies showing up to 90% of patients reporting significant improvement in symptoms. While Botox is used off-label for TMJ (not FDA-approved for this specific indication), it is widely used by dentists, oral surgeons, neurologists, and pain specialists.

TMJ Symptoms That Botox Can Treat

Symptom	How Botox Helps	Improvement Timeline
Jaw pain / soreness	Relaxes overactive masseter and temporalis muscles	1-2 weeks
Teeth grinding (bruxism)	Reduces clenching force by 20-40%, protecting teeth	1-2 weeks
Jaw clenching	Prevents involuntary clenching, especially during sleep	1-2 weeks
Tension headaches	Reduces muscle tension that triggers temporal headaches	2-4 weeks
Jaw clicking/popping	Reduces muscle pressure on the TMJ disc	2-4 weeks (partial)
Lockjaw / limited opening	Relaxes muscle spasm allowing greater range of motion	1-3 weeks
Ear pain (referred)	Reduces masseter tension that refers pain to the ear	2-3 weeks
Tooth damage prevention	Reduces grinding force, protecting enamel and dental work	Immediate (reduced force)

Botox vs. Night Guard for Bruxism

Feature	Masseter Botox	Night Guard / Splint
Mechanism	Reduces clenching force at the source	Protects teeth but doesn't reduce force
Reduces grinding?	✔ Yes — reduces episodes by 20-40%	✘ No — grinding still occurs
Reduces pain?	✔ Yes — relaxes muscle tension	Partial — reduces tooth pain only
Reduces headaches?	✔ Yes	✘ No
Slims jaw?	✔ Yes — bonus cosmetic benefit	✘ No
24/7 protection?	✔ Day and night	Night only (most patients)
Compliance needed?	None — works automatically	Must remember to wear it
Comfort	5-min injection, no device to wear	Bulky, can cause drooling, some find uncomfortable
Cost	$400-$900 every 4-6 months	$300-$1,000 (custom), lasts 2-5 years
Can be combined?	✔ Yes — many patients use both. Botox reduces force while guard protects enamel.

                    Insurance Coverage: While masseter Botox for cosmetic jaw slimming is never covered by insurance, Botox for TMJ and bruxism may be partially covered under medical (not dental) insurance, especially with documented diagnosis and failed conservative treatments. Some plans cover it under "chronic pain management." Ask your provider to submit with diagnosis codes for TMJ disorder (M26.60) or bruxism (G47.63). Coverage varies widely by plan.
                

Masseter Botox Cost

Masseter Botox pricing depends on the number of units used, your provider's per-unit rate, and geographic location. Because the masseter requires more units than cosmetic facial Botox, the total cost is typically higher per session.

Cost Breakdown

Pricing Model	Rate	50 Units Total	80 Units Total	100 Units Total
Per-Unit Pricing	$10-$15/unit	$500-$750	$800-$1,200	$1,000-$1,500
Flat-Rate Masseter Package	Fixed fee	$400-$900 (includes typical dosing)

Annual Cost Estimate

Treatment Year	Sessions/Year	Units Per Session	Annual Cost
Year 1 (Building)	2-3 sessions	60-100 units	$800-$2,700
Year 2+ (Maintenance)	2 sessions	40-60 units	$500-$1,800

Masseter Botox vs. Other Jaw Treatments: Cost Comparison

Treatment	Cost	Duration	Invasiveness	Downtime
Masseter Botox	$400-$900	4-6 months	Non-surgical	None
Night guard (custom)	$300-$1,000	2-5 years	Non-invasive	None
Jaw reduction surgery (V-line)	$5,000-$15,000	Permanent	Surgical (bone shaving)	2-4 weeks
Buccal fat removal	$2,000-$5,000	Permanent	Surgical (intraoral)	1-2 weeks
Physical therapy (TMJ)	$150-$300/session	Ongoing	Non-invasive	None

Side Effects & Risks

Masseter Botox is generally very safe, but because the injection site is near important anatomical structures (parotid gland, facial nerve branches, risorius muscle), proper injection technique is critical.

Common Side Effects

Side Effect	Frequency	Duration	Management
Mild soreness at injection site	Very common (70%+)	1-2 days	Ice if needed, resolves on its own
Temporary chewing difficulty	Common (40-50%)	1-3 weeks	Eat softer foods initially, adapts quickly
Mild bruising	Occasional (20-30%)	3-7 days	Arnica, concealer, avoid blood thinners pre-treatment
Jaw muscle fatigue	Common (30-40%)	2-4 weeks	Normal response, indicates Botox is working
Headache	Occasional (10-15%)	1-2 days	Acetaminophen

Rare Side Effects

Side Effect	Frequency	Notes
Asymmetric smile	Rare (<1%)	Occurs if Botox migrates to risorius or zygomaticus muscles. Temporary — resolves in 2-4 weeks.
Facial hollowing (over-treatment)	Uncommon (2-5%)	Can occur with excessive dosing or in patients with minimal facial fat. Sunken appearance at jaw angles. Reversible.
Parotid gland effects	Very rare (<1%)	If Botox reaches the nearby parotid gland, may cause temporary dry mouth. Proper injection placement prevents this.
Paradoxical bulging	Very rare (<1%)	If only superficial masseter is treated, the deep masseter may compensate and bulge. Addressed in follow-up.

                    Facial Hollowing Risk: The most discussed concern with repeated masseter Botox is facial hollowing — where excessive muscle reduction creates a gaunt or sunken appearance at the jaw angles. This is more common in patients who are already thin-faced or who receive very high doses over many years. A skilled injector will calibrate dosing to slim the jaw without over-reducing the muscle, especially in patients with less facial fat.
                

Aftercare Instructions

Masseter Botox aftercare is similar to standard Botox aftercare, with a few jaw-specific considerations:

DO

Clench your jaw gently a few times after injection (helps Botox bind to muscle)
Stay upright for 4 hours after treatment
Apply ice if you feel soreness at injection sites
Eat softer foods for the first few days if chewing feels weak
Continue wearing your night guard if you use one
Return for follow-up in 2-4 weeks if asymmetry is noticed

DON'T

Massage or rub the injection area for 24 hours
Chew gum excessively for the first week
Exercise strenuously for 24 hours
Lie face-down for 4 hours after treatment
Get dental work for 2 weeks (prolonged mouth opening can shift Botox)
Drink alcohol for 24 hours

Are You a Good Candidate?

Ideal Candidates

Wide or square jaw from enlarged masseter muscles
Diagnosed TMJ disorder or chronic jaw pain
Teeth grinding (bruxism) — day or night
Jaw clenching causing headaches or tooth damage
Wanting non-surgical jaw slimming / V-line
Night guard isn't providing enough relief
Adequate facial fat (not extremely gaunt)
Over 18 years old

Not Recommended For

Very thin face with minimal facial fat (hollowing risk)
Jaw width from bone structure, not muscle (Botox can't slim bone)
Neuromuscular disorders (myasthenia gravis, ALS)
Allergy to botulinum toxin or albumin
Pregnant or breastfeeding
Active infection at the injection site
Expecting immediate results (takes 4-8 weeks for slimming)

Masseter Botox vs. Other Jaw Slimming Options

Feature	Masseter Botox	V-Line Surgery	Buccal Fat Removal	Jaw Contouring Filler
What it targets	Masseter muscle	Jawbone (mandible)	Cheek fat pads	Jawline definition
Goal	Slim lower face	Slim lower face	Slim mid-face	Define/sharpen jawline
Invasiveness	Injection (5 min)	Surgery (2-4 hrs)	Surgery (30-60 min)	Injection (15 min)
Anesthesia	None / topical	General	Local or general	Topical / local
Downtime	None	2-4 weeks	1-2 weeks	None
Results visible	4-8 weeks	3-6 months (swelling)	2-4 weeks	Immediate
Duration	4-6 months	Permanent	Permanent	12-24 months
Reversible?	✔ Yes	✘ No	✘ No	✔ Yes (dissolvable)
Cost	$400-$900/session	$5,000-$15,000	$2,000-$5,000	$600-$2,000
TMJ/bruxism relief?	✔ Yes	✘ No	✘ No	✘ No

Frequently Asked Questions

How many units of Botox for the masseter?

Most patients need 25-50 units of Botox per side (50-100 units total) for masseter treatment. First-time patients typically start with 25-30 units per side, while patients with larger or stronger masseter muscles may need 40-50 units per side. The dosage is adjusted based on muscle size, jaw strength, and treatment goals (cosmetic slimming vs. therapeutic TMJ/bruxism relief).

How much does masseter Botox cost?

Masseter Botox costs $400-$900 per session, depending on the number of units used and your provider's pricing. At $10-$15 per unit with 50-100 units total, the typical range is $500-$1,500. Some providers offer flat-rate masseter packages. TMJ/bruxism treatment with the same dosing costs similarly. Results last 4-6 months, so annual cost is typically $800-$2,700 for 2-3 sessions per year.

Does masseter Botox change your face shape?

Yes, masseter Botox gradually slims the lower face by reducing the size of the masseter muscle. Over 4-8 weeks, the muscle atrophies (shrinks) from reduced use, creating a slimmer, more V-shaped jawline. The change is gradual and natural-looking — not an overnight transformation. The degree of slimming depends on how enlarged your masseter muscles are. Patients with significant masseter hypertrophy see the most dramatic results.

Can Botox help with TMJ pain?

Yes, Botox is an effective treatment for TMJ (temporomandibular joint) disorders. By relaxing the masseter and temporalis muscles, Botox reduces jaw tension, clenching force, and associated pain. Studies show up to 90% of TMJ patients report significant improvement. Relief typically begins within 1-2 weeks and lasts 3-6 months. While Botox is used off-label for TMJ (not FDA-approved for this specific indication), it is widely used by dentists, oral surgeons, and pain specialists.

How long does masseter Botox last?

Masseter Botox typically lasts 4-6 months, which is longer than Botox in smaller facial muscles (which lasts 3-4 months). With consistent treatments, results tend to last longer over time as the muscle gradually atrophies from repeated relaxation. Some patients find that after 3-4 treatment cycles, they can extend intervals to every 6-9 months as the muscle has reduced in size.

Does masseter Botox hurt?

Masseter Botox involves minimal pain. The masseter is a thick muscle, and most patients describe the injections as a mild pinch or pressure. Typically 3-5 injection points are used per side with a very fine needle (30-32 gauge). The entire procedure takes about 5-10 minutes. Ice or topical numbing cream can be applied beforehand, but most patients don't require it. Pain is rated 2-3 out of 10 by most patients.

Can masseter Botox affect my smile?

When performed correctly, masseter Botox should not affect your smile. The masseter muscle controls jaw clenching and chewing — not smiling. Smiling is controlled by the zygomaticus and risorius muscles. However, if Botox migrates to nearby muscles (risorius or buccinator), it could temporarily cause an asymmetric or weakened smile. This is rare (less than 1%) and temporary, resolving as the Botox wears off. Choosing an experienced injector who understands facial anatomy is crucial.

Will masseter Botox make it hard to chew?

You may notice mild difficulty chewing very hard or tough foods (like steak or hard candy) for the first 2-4 weeks as the muscle relaxes. This is temporary and most patients adapt quickly. Normal eating is not affected. The masseter is one of the strongest muscles in the body, and even with Botox, it retains enough function for everyday chewing. The medial pterygoid and temporalis muscles also assist with chewing.

Is masseter Botox safe long-term?

Yes, long-term masseter Botox is considered safe based on current evidence. Studies following patients over 2+ years of repeated treatments show no significant adverse effects. The muscle reduction is reversible — if you stop treatment, the masseter gradually returns to its original size over 6-12 months. One consideration: very long-term use (5+ years) may cause some bone density changes in the jaw from reduced muscle loading, but this is still being studied and has not been shown to cause clinical problems.

What is the difference between cosmetic and therapeutic masseter Botox?

The injection technique is essentially the same — Botox is injected into the masseter muscle in both cases. The difference is the primary goal: cosmetic masseter Botox aims for jaw slimming and facial contouring (creating a V-shaped face), while therapeutic masseter Botox aims to relieve TMJ pain, bruxism (teeth grinding), and jaw clenching. Many patients get both benefits from one treatment. Insurance may cover therapeutic masseter Botox for documented TMJ/bruxism but never covers cosmetic treatment.

Masseter Botox: Jaw Slimming & TMJ Treatment

The Complete Guide to Masseter Botox for Jaw Slimming & TMJ in 2026

In This Guide