Aesthetics & Wellness
Botox for Jaw Clenching (Masseter): What to Know
Published · Haute MD Editorial Team
Masseter Botox means injecting a botulinum toxin, such as Botox, into the masseters, the large chewing muscles at the angle of the jaw, to relax them. People get it for two reasons: to ease clenching or grinding (bruxism) and related jaw-muscle pain, or to slim a square or wide lower face caused by enlarged masseters. In the U.S. both uses are off-label: no masseter, bruxism or TMJ use appears on the FDA labels for BOTOX, BOTOX Cosmetic or Xeomin. FDA is reviewing an application, accepted in August 2026, to add masseter muscle prominence to BOTOX Cosmetic's label, but it has not been approved. Results usually appear within about two weeks and last about three to four months. Evidence is stronger for jaw slimming than for clenching or TMJ pain, and a night guard and other conservative care usually come first.
At a glance
Goal: For clenching, bruxism or jaw-muscle pain: Reduce clenching force, muscle tension and muscle-related jaw pain. For jaw slimming: Soften a square or wide lower face from enlarged (hypertrophic) masseters. FDA status: For clenching, bruxism or jaw-muscle pain: Off-label. Not on the BOTOX, BOTOX Cosmetic or Xeomin labels; FDA "has not yet approved Botox" for TMD (Cleveland Clinic). For jaw slimming: Off-label today. A BOTOX Cosmetic application for masseter muscle prominence was accepted for FDA review Aug. 4, 2026; not approved as of Oct. 24, 2026. Strength of evidence: For clenching, bruxism or jaw-muscle pain: Mixed. Reviews call the evidence for muscle-related TMD "equivocal" and for bruxism "not entirely unequivocal"; very little for TMJ joint disorders. For jaw slimming: Good short-term evidence: a 2026 meta-analysis of 5 placebo-controlled trials (536 people) found improved prominence, thinner muscle and higher satisfaction. Usually tried: For clenching, bruxism or jaw-muscle pain: After conservative care (night guard, physical therapy, stress management). For jaw slimming: As an elective cosmetic treatment. When you notice it: For clenching, bruxism or jaw-muscle pain: A day to a couple of weeks (Cleveland Clinic). For jaw slimming: Usually 10–14 days (Practical Dermatology); visible slimming builds as the muscle shrinks. How long it lasts: For clenching, bruxism or jaw-muscle pain: About 3–4 months (Cleveland Clinic). For jaw slimming: About 3–4 months on average; repeat treatment maintains results (Practical Dermatology). Sources: DailyMed labels for BOTOX Cosmetic (Jan. 8, 2026), BOTOX (Aug. 3, 2026) and Xeomin (July 13, 2026); AbbVie/Allergan Aesthetics, Aug. 4, 2026; Cleveland Clinic; Delcanho et al. 2022; BDJ 2019; Machado et al. 2026; Practical Dermatology. Checked Oct. 24, 2026.
What masseter Botox is
The masseter runs from the cheekbone to the angle of the lower jaw and is the main muscle that closes your bite. Clenching or grinding works it hard, and in some people it enlarges (masseter hypertrophy), which widens the lower face. A botulinum toxin blocks the nerve signal that tells the muscle to contract. Injected into the masseter, it: reduces bite force temporarily. In a 2023 trial, 50 units of Xeomin (25 per side) significantly lowered maximum bite force at 3 months, but the effect was no longer significant at 6 months. lets the muscle shrink over time. A 2022 review of 28 studies found average masseter thickness fell by roughly 12% to 31% at three months, depending on technique. The authors cautioned that the studies varied widely and had a high risk of bias. It doesn't fix the cause of clenching, such as stress, sleep problems or bite issues, and it doesn't treat problems inside the jaw joint itself.
Is it FDA-approved?
Not for the jaw, as of Oct. 24, 2026. BOTOX Cosmetic is approved for frown lines between the brows, crow's feet, forehead lines and platysma bands in the neck. BOTOX (the medical version) is approved for conditions including chronic migraine, spasticity, cervical dystonia, excessive underarm sweating and certain bladder and eye-muscle conditions. None of the labels we checked (BOTOX, BOTOX Cosmetic and Xeomin) lists the masseter, bruxism or TMJ disorders. Doctors may legally use an approved drug off-label based on their medical judgment. Ask your injector which product they use and why. What's pending: on Aug. 4, 2026, Allergan Aesthetics said FDA had accepted for review its application to add "the temporary improvement in the appearance of marked to very marked masseter muscle prominence" to BOTOX Cosmetic's label. The company says two Phase 3 trials met their main goals versus placebo with no new safety signals. Acceptance for review is not approval. Even if it is approved, that indication would be cosmetic (the look of a prominent masseter), not treatment of grinding or TMJ pain.
Does it work for clenching, grinding and TMJ pain?
Sometimes, and the evidence is mixed. A 2022 review of 24 randomized trials in the Journal of Oral & Facial Pain and Headache found: "good scientific evidence" for masseter hypertrophy; "equivocal evidence" for muscle-related (myogenous) TMD; "very little" evidence for TMJ joint (articular) disorders. Doses and injection methods varied widely. A 2019 systematic review in the British Dental Journal called the evidence for TMD and bruxism "not entirely unequivocal." It said conservative options, "such as self-management with explanation and physical therapies, should be exhausted first." Cleveland Clinic says research suggests Botox may help some symptoms, such as grinding, more than others, such as pain. It is usually a supplement to physical therapy, splints or night guards and medication, used when those aren't enough. Start with a dentist or doctor who can check your bite, teeth and joint. See What is teeth grinding? and What is TMJ disorder?
Does it slim the jaw?
In people with enlarged masseters, yes, temporarily. A 2026 meta-analysis (Journal of Plastic, Reconstructive & Aesthetic Surgery) pooled five placebo-controlled trials with 536 participants. Botulinum toxin type A improved masseter prominence scores, reduced muscle thickness and raised patient satisfaction in the short term. The authors noted substantial differences between studies. They said current evidence can't yet define an optimal dose or protocol. Slimming only happens if the width comes from muscle. A wide jaw from bone structure or fat won't respond the same way, which is why the assessment matters. See also What is facial balancing?
What to expect
The visit: a few injections into each masseter, usually after the doctor feels the muscle while you clench and checks for differences between sides. Onset: a day to a couple of weeks for clenching relief (Cleveland Clinic). For slimming, the effect usually starts about 10–14 days after injection and becomes more visible as the muscle shrinks. Duration: about three to four months on average, so repeat treatments are needed to keep results. See How long does Botox last? and Botox vs. Dysport.
Side effects and safety
Common or expected: pain, bruising, swelling or redness at the injection sites; headache or neck pain, and flu-like symptoms (Cleveland Clinic). Specific to the masseter: Chewing weakness or fatigue, especially with tough foods. A clinician review in Practical Dermatology calls it the most common side effect, in about 30% of patients, more often with higher doses, appearing one to four weeks after treatment. An uneven or "fixed"-looking smile if the toxin affects nearby muscles (Cleveland Clinic). Asymmetry, or paradoxical bulging of part of the muscle when chewing. Worsened jowls or sagging in some people, especially those with looser skin or over 40, as the muscle shrinks. Changes in jawbone volume: one randomized trial in the 2022 review found dose-related decreases in bone volume at two points on the jaw (the coronoid and condylar processes), along with a temporary drop in chewing performance. Long-term effects of repeated treatment aren't well studied. Boxed warning: all botulinum toxin products carry an FDA boxed warning that their effect may spread beyond the injection site, causing symptoms such as muscle weakness, double vision, drooping eyelids, or trouble swallowing, speaking or breathing, hours to weeks after injection. The BOTOX Cosmetic label notes such spread has been reported in both approved and unapproved uses. Get emergency care for any trouble swallowing, speaking or breathing. Avoid counterfeit or "back-alley" Botox. Cleveland Clinic warns that unlicensed providers may use counterfeit products, and the CDC issued an alert about it in 2024. Get injections only from a licensed clinician in a medical setting.
Who should inject?
Choose a licensed, experienced physician or dentist who: evaluates both your bite and jaw and your facial anatomy before treating; explains the off-label status; tells you which product and dose they plan to use. Cleveland Clinic says Botox for TMD requires more precision than cosmetic injections and should be given by an oral surgeon, an ENT (otolaryngologist) or an experienced plastic surgeon. For jaw slimming, board-certified dermatologists and plastic surgeons commonly treat the masseter.
Questions to ask at your consultation
1. Is my problem muscle-related (clenching, enlarged masseters) or a joint problem? Should I try a night guard or physical therapy first? 2. Which product will you use, and is this use on its FDA label or off-label? 3. How many units per side, and where exactly will you inject? 4. When should I expect results, how long will they last and when would I come back? 5. What side effects are most likely for me, especially chewing weakness, an uneven smile or sagging? 6. How many masseter treatments have you performed, and who will do the injections? More: Botox and filler consultation questions.
Find a doctor
Browse dermatologists, cosmetic dentists or Find a Doctor on Haute MD. Featured doctors: Dr. Jessica Weiser, a board-certified dermatologist and laser specialist at Weiser Skin MD in SoHo, New York and Aspen, whose practice offers injectables such as Botox; and Dr. Mimi Yeung, DDS, a cosmetic and general dentist at M.Y. Dental Spa in Midtown Manhattan whose practice includes TMJ care. Haute MD members are featured through paid membership. Membership is not an endorsement or a ranking.
Sources
1. BOTOX Cosmetic (onabotulinumtoxinA) prescribing information, DailyMed (published Jan. 8, 2026; indications and boxed warning). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=485d9b71-6881-42c5-a620-a4360c7192ab (fetched 2026-10-24). 2. BOTOX (onabotulinumtoxinA) prescribing information, DailyMed (published Aug. 3, 2026). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=33d066a9-34ff-4a1a-b38b-d10983df3300 (fetched 2026-10-24). 3. XEOMIN (incobotulinumtoxinA) prescribing information, DailyMed (published July 13, 2026). https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=3f35d6e0-3450-4abc-a0da-cc7b277e7c6e (fetched 2026-10-24). 4. AbbVie / Allergan Aesthetics, "Allergan Aesthetics Announces U.S. FDA Acceptance of Supplemental Biologics License Application for BOTOX® Cosmetic for Masseter Muscle Prominence" (Aug. 4, 2026). https://news.abbvie.com/2026-08-04-Allergan-Aesthetics-Announces-U-S-FDA-Acceptance-of-Supplemental-Biologics-License-Application-for-BOTOX-R-Cosmetic-for-Masseter-Muscle-Prominence (fetched 2026-10-24). 5. Cleveland Clinic, "Botox for TMJ Pain: What To Expect" (Jan. 6, 2025; with Karyn Kahn, DDS). https://health.clevelandclinic.org/beyond-wrinkles-why-botox-works-for-jaw-pain-and-tmj (fetched 2026-10-24). 6. Delcanho R, et al. "Botulinum Toxin for Treating Temporomandibular Disorders: What is the Evidence?" J Oral Facial Pain Headache. 2022;36(1):6–20. doi:10.11607/ofph.3023. https://pmc.ncbi.nlm.nih.gov/articles/PMC10586579/ (fetched 2026-10-24). 7. "A systematic review of botulinum toxin in the management of patients with temporomandibular disorders and bruxism." Br Dent J. Published May 10, 2019. https://www.nature.com/articles/s41415-019-0257-z (fetched 2026-10-24). 8. Machado GF, 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. PMID 42379083. https://pubmed.ncbi.nlm.nih.gov/42379083/ (fetched 2026-10-24). 9. Ågren M, et al. "Duration of bite force reduction following a single injection of botulinum toxin in the masseter muscle bilaterally: A one-year non-randomized trial." J Oral Rehabil. 2023;50(5):343–350. PMID 36810787. https://pubmed.ncbi.nlm.nih.gov/36810787/ (fetched 2026-10-24). 10. Rauso R, et al. "Botulinum toxin type A injections for masticatory muscles hypertrophy: A systematic review." J Craniomaxillofac Surg. 2022;50(1):7–18. PMID 34620536. https://pubmed.ncbi.nlm.nih.gov/34620536/ (fetched 2026-10-24). 11. Practical Dermatology, "Slimming the Masseters with Neuromodulator Injections" (author and date not shown). https://practicaldermatology.com/topics/aesthetics-cosmeceuticals/slimming-the-masseters-with-neuromodulator-injections/23648/ (fetched 2026-10-24).
Medical disclaimer
This page is for general education and is not medical advice. Talk with a licensed dentist, board-certified dermatologist or plastic surgeon about your situation.
Frequently Asked Questions
What is masseter Botox?
Injections of a botulinum toxin, such as Botox, into the masseter (jaw) muscles to relax them, either to ease clenching or grinding or to slim a wide lower face caused by enlarged muscles.
Is Botox for jaw clenching FDA-approved?
No. Using Botox for clenching, grinding (bruxism), TMJ disorders or jaw slimming is off-label in the U.S. FDA accepted an application in August 2026 to add masseter muscle prominence to BOTOX Cosmetic's label, but it had not been approved as of Oct. 24, 2026.
Does Botox help teeth grinding?
It can reduce clenching force, and some patients improve, but systematic reviews call the evidence mixed. A night guard and other conservative treatments are usually tried first, and Botox doesn't treat the underlying cause.
How long does masseter Botox last?
About three to four months on average, according to Cleveland Clinic and a clinician review in Practical Dermatology. Repeat treatments are needed to maintain results.
How long until I see results?
Relief from clenching can begin within a day to a couple of weeks. A slimmer jawline usually starts to show about 10–14 days after injection and becomes more visible as the muscle shrinks.
What are the side effects of masseter Botox?
Most often injection-site bruising or soreness and temporary chewing weakness. Others include an uneven smile, asymmetry, sagging or jowling in some people, and the boxed-warning risk of toxin spread. Get emergency care for any trouble swallowing, speaking or breathing.
Who should do masseter Botox?
A licensed, experienced physician or dentist who evaluates your bite and facial anatomy, explains the off-label status and tells you which product and dose they'll use.
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