Seoul
Chief MD, Gangnam
Duk-ha Kim
The trust our patients have placed in this clinic was built on conviction and principle. We intend to hold to both, unchanged, through the next hundred years.
Botulinum toxin treatment guide
Masseter Toxin
Masseter toxin injects botulinum toxin type A into the masseter, the chewing muscle over the angle of the jaw. Korea registered this use first and did so for a single product, Nabota; China approved BOTOX Cosmetic for it in 2024; in the United States it remains an off-label use with a supplemental application still under FDA review.
- Target tissue
- Masseter — the chewing muscle at the jaw angle
- Korea
- Nabota only: benign masseter hypertrophy, adults 18 to 65
- United States
- Not approved — sBLA accepted for review on 2026-08-04
- China
- BOTOX Cosmetic approved for masseter muscle prominence, launched 2024-09
What is masseter toxin, and which muscle does it target?
Masseter toxin is an injection of botulinum toxin type A into the masseter, the chewing muscle that sits over the angle of the jaw. The Korean MFDS record for Nabota describes the registered use as a temporary improvement of the lower facial contour in patients with marked to very marked benign masseter hypertrophy, in adults aged 18 to 65. That wording matters: the approved claim is about appearance, it is temporary, and it is written for a graded clinical finding rather than for anyone who wants a narrower lower face.
How does a toxin injection change a chewing muscle?
Botulinum toxin type A blocks the release of acetylcholine at the neuromuscular junction, so the injected part of the muscle contracts less. Reduced contraction over time is followed by atrophy of the treated muscle fibres. Nothing is removed — no fat, no bone — and the effect recedes as nerve terminals recover. Published work on masticatory muscles describes this as dose-dependent denervation, which is why the dose and the injection points are clinical decisions rather than a fixed recipe.
Sources: FDA label — BOTOX Cosmetic (onabotulinumtoxinA)Aesthetic Plast Surg 2026;50(3):1320-1328 — masticatory muscle changes after botulinum toxin
Why is this approved in Korea but not in the United States?
Because approval is granted country by country. Korea added benign masseter hypertrophy to the Nabota record on 2023-08-25, which made it the first market to register the use. China followed: the NMPA approved BOTOX Cosmetic for masseter muscle prominence in adults, launched in September 2024. In the United States the BOTOX Cosmetic label covers glabellar lines, lateral canthal lines, forehead lines and platysma bands and does not list the masseter, so injecting it there is off-label; on 2026-08-04 Allergan Aesthetics announced that the FDA had accepted a supplemental Biologics License Application for masseter muscle prominence. Acceptance means the file entered review, not that it was approved, and no action date was published. Japan does not list the masseter among the approved indications for its botulinum toxin products either.
Sources: MFDS drug product record — Nabota 50 U (Daewoong)FDA label — BOTOX Cosmetic (onabotulinumtoxinA)Allergan Aesthetics — FDA acceptance of sBLA for masseter muscle prominence (2026-08-04)Allergan Aesthetics — BOTOX Cosmetic for MMP launched in China (2024-09-11)
Does every toxin sold in Korea carry the masseter indication?
No — and this is the single most useful thing to know before a consultation. Korean approval is per product, not per category. The MFDS record for Nabota lists benign masseter hypertrophy in adults aged 18 to 65; the MFDS record for Meditoxin lists four indications and masseter hypertrophy is not among them. So the sentence approved in Korea describes one product. The practical question is therefore which product name is on the vial, and whether that product holds the indication or is being used off-label.
Sources: MFDS drug product record — Nabota 50 U (Daewoong)MFDS drug product record — Meditoxin (Medytox)
What did the pooled trial data actually measure?
A 2026 meta-analysis in the Journal of Plastic, Reconstructive and Aesthetic Surgery pooled five placebo-controlled randomised trials with 536 participants in total, and the primary assessment point was four weeks. For reaching a masseter prominence or hypertrophy score of 3 or lower, the relative risk against placebo was 5.25 (95% CI 1.88 to 14.66) in the 48-unit arms and 3.66 (95% CI 1.29 to 10.34) in the 72-unit arms. The authors report substantial heterogeneity between the trials and a lack of long-term follow-up. Read those figures as a four-week endpoint measured against placebo, not as a statement about how long anything lasts.
Sources: Machado GF et al., J Plast Reconstr Aesthet Surg 2026;119:212-225
What does repeated injection do to chewing function?
A 2026 systematic review in Aesthetic Plastic Surgery examined 14 studies of botulinum toxin in masticatory muscles — 2 in humans and 12 in animals. It reports dose-dependent denervation and reduced function of the treated muscles, and that recovery after atrophy was incomplete in the studies reviewed. The authors state plainly that the human evidence base is limited to two studies, so this is a documented signal to raise at the consultation rather than a quantified rate. It is also the reason this treatment is not a cosmetic decision on the same footing as a surface procedure: the target is a muscle you use to eat.
Sources: Aesthetic Plast Surg 2026;50(3):1320-1328 — masticatory muscle changes after botulinum toxin
Can you compare brands by the number of units quoted?
No. Potency units are defined by each manufacturer through its own assay and are specific to that preparation; the BOTOX Cosmetic label states directly that its units are not interchangeable with other botulinum toxin products. A quote of the same number from two different products is not the same dose. The 48-unit and 72-unit arms in the pooled trials are the doses those studies happened to use, not a prescription and not a conversion table — ask for the product name and the dose in that product’s own units together, never one without the other.
Sources: FDA label — BOTOX Cosmetic (onabotulinumtoxinA)Machado GF et al., J Plast Reconstr Aesthet Surg 2026;119:212-225
How long does the effect last?
The pooled trial data’s primary assessment point was four weeks after injection, comparing the 48-unit and 72-unit arms against placebo — a single measured point, not a stated duration, and the authors themselves report a lack of long-term follow-up beyond it. The underlying mechanism points to what actually ends the effect: botulinum toxin blocks acetylcholine release at the neuromuscular junction, and the effect recedes as nerve terminals recover, which is a biological process rather than a fixed calendar date. Repeat-injection literature adds a caution to that picture: a 2026 systematic review of masticatory-muscle studies found that recovery after atrophy was incomplete in the studies it reviewed, though its human evidence base is limited to two studies. Taken together, the interval before a repeat injection is a clinical judgment based on how much muscle function and bulk has returned, not a number fixed by the trial data cited here. Ask the injecting doctor how they assess that recovery before deciding to re-inject, and what would lead them to recommend waiting longer.
Sources: Machado GF et al., J Plast Reconstr Aesthet Surg 2026;119:212-225Aesthetic Plast Surg 2026;50(3):1320-1328 — masticatory muscle changes after botulinum toxin
When should a masseter injection not go ahead?
Botulinum toxin is contraindicated in people with known hypersensitivity to any botulinum toxin preparation or to the components of the formulation, and where there is infection at the proposed injection site. The labelling carries a boxed warning about distant spread of toxin effect, and calls for caution in neuromuscular disorders such as myasthenia gravis, Lambert-Eaton syndrome and amyotrophic lateral sclerosis, and in people with existing swallowing or breathing difficulty. For this site specifically, chewing fatigue and asymmetry of the jaw line or smile belong in the discussion, because the masticatory-muscle literature documents functional decline in the treated muscles. Pregnancy, breastfeeding, current medicines and previous toxin injections all need to be disclosed and reviewed.
Sources: FDA label — BOTOX Cosmetic (onabotulinumtoxinA)Aesthetic Plast Surg 2026;50(3):1320-1328 — masticatory muscle changes after botulinum toxin
What should you confirm before you agree to the injection?
Ask which product will be injected, and whether that product holds a masseter indication in the country where you are being treated or is being used off-label. Ask for the dose stated in that product’s own units, the number of injection points per side, whether the plan covers one side or both, and the planned interval before any repeat. Disclose previous toxin injections with dates and product names, jaw pain, clicking or limited mouth opening, teeth grinding, medicines and pregnancy or breastfeeding. Agree in advance which symptoms should trigger a call back: difficulty chewing, a changed bite, an uneven smile, or any swallowing or breathing change.
Sources: MFDS drug product record — Nabota 50 U (Daewoong)FDA label — BOTOX Cosmetic (onabotulinumtoxinA)
Is this the same treatment as toxin for wrinkles?
Same drug class, different tissue and different planning. Wrinkle toxin is placed in thin muscles of facial expression such as the glabellar, forehead and lateral canthal groups, which is what the U.S. BOTOX Cosmetic label covers. The masseter is a thick chewing muscle, so depth, dose and the pre-treatment questions are not the same, and the approvals are granted separately — a product licensed for frown lines is not automatically licensed for the masseter anywhere. Procedures aimed at the same visual area but at other tissue, such as buccal fat removal or jaw-angle surgery, are a different category again; this page holds no data comparing them.
Sources: FDA label — BOTOX Cosmetic (onabotulinumtoxinA)MFDS drug product record — Nabota 50 U (Daewoong)
Which market approved this, and for which product?
Approval for masseter injection is decided per country and per product, and the two answers do not travel together. This table maps the regulatory records cited on this page. It is not a comparison of how well the products work.
| Market | Masseter indication | What the record says | What to confirm |
|---|---|---|---|
| Korea — Nabota (Daewoong) | Approved | MFDS record lists benign masseter hypertrophy in adults aged 18 to 65, for temporary improvement of the lower facial contour in marked to very marked cases; indication added 2023-08-25 | That the vial used is this product, and the dose stated in its own units |
| Korea — other toxin products | Not on the record | The MFDS record for Meditoxin lists four indications and masseter hypertrophy is not among them | Whether the product offered holds the indication, or is being used off-label |
| United States | Not approved | The BOTOX Cosmetic label covers glabellar, lateral canthal and forehead lines and platysma bands; an sBLA for masseter muscle prominence was accepted for FDA review on 2026-08-04 | That any mention of FDA clearance in a clinic’s wording refers to a different indication, not to the masseter |
| China (mainland) | Approved | NMPA approved BOTOX Cosmetic for masseter muscle prominence in adults; launched September 2024 | That the product is the presentation approved for this use, not a different toxin |
| Japan | Not among approved indications | The masseter is not listed among the approved indications for botulinum toxin products there | The current package insert for the product actually being used |
This table maps regulatory records only. Approval status says nothing about whether the treatment suits you, and this page holds no head-to-head data between products.
Sources: MFDS drug product record — Nabota 50 U (Daewoong)MFDS drug product record — Meditoxin (Medytox)FDA label — BOTOX Cosmetic (onabotulinumtoxinA)Allergan Aesthetics — FDA acceptance of sBLA for masseter muscle prominence (2026-08-04)Allergan Aesthetics — BOTOX Cosmetic for MMP launched in China (2024-09-11)
Medical care at Abijou
Care is provided by the medical team at the branch you select. These clinicians lead the three branches linked from this guide; confirm the doctor assigned to your visit with that branch.
Chief MD, Myeongdong
Cheol-su Yoon
I want to be thinking about how the patient feels right up to the last moment of the procedure.
Chief MD, Hongdae
Jae-wook Kim
I will give my best with the attentiveness to catch even the smallest change.
Listed branch medical team — not a medical-review byline for this article.
Frequently asked questions
What is masseter toxin?
It is an injection of botulinum toxin type A into the masseter, the chewing muscle over the angle of the jaw. Korea registered this use for one product: the MFDS record for Nabota lists benign masseter hypertrophy in adults aged 18 to 65, for temporary improvement of the lower facial contour in marked to very marked cases. China approved BOTOX Cosmetic for masseter muscle prominence, launched in September 2024. In the United States it is not an approved use.
Jaw Botox, face slimming injection, masseter reduction — are these all the same thing?
They are menu names for the same injection, and none of them tells you which product is used. Botox is a brand name rather than a category, and approvals, unit definitions and licensed indications differ between products. Before comparing two menus, ask for the product name on the vial and the dose expressed in that product’s own units.
Does the muscle shrink, or is fat being removed?
The muscle. Botulinum toxin type A blocks acetylcholine release at the nerve ending, the injected part of the masseter contracts less, and reduced use is followed by atrophy of those fibres. No fat and no bone is removed, and the effect fades as nerve terminals recover.
Nabota or BOTOX Cosmetic — which one is actually approved for the masseter?
It depends on the country, and neither answer is global. In Korea the masseter indication sits on Nabota, and other toxin products sold there do not carry it — the MFDS record for Meditoxin lists four indications and masseter hypertrophy is not one of them. In mainland China the approved product for masseter muscle prominence is BOTOX Cosmetic. In the United States BOTOX Cosmetic is not approved for it, and the supplemental application accepted on 2026-08-04 is still under review.
Is having it done in Korea different from having it done at home?
The product and its licensed indication can differ; the anatomy does not. Korea is where the indication was first registered, and it applies to Nabota in adults aged 18 to 65. Elsewhere the same injection may be off-label — in the United States it currently is, since the FDA has only accepted an application for review. Off-label use is a documented clinical decision, not an approved indication, so ask which of the two situations applies to the product being offered to you.
Masseter toxin, buccal fat removal or jaw-angle surgery — how do they differ?
They act on different tissue: toxin on the chewing muscle, buccal fat removal on fat, angle-reduction surgery on bone. Toxin is temporary and recedes, while the other two remove tissue. This page holds no data comparing them and cannot rank them; what is actually making a lower face look wide is a judgement that needs an in-person assessment.
Does the injection hurt, and is there downtime?
It is a needle injection into a deep muscle, so the pain is brief, and bruising or tenderness at the injection points is possible. The trials pooled in the 2026 meta-analysis reported a prominence score at four weeks and did not publish a pain scale or a recovery timetable, so this page cannot quote one. Ask the treating clinic what to expect on the day and what to avoid afterwards.
When would a change be visible, and how long does it last?
The pooled evidence measures four weeks and does not answer the duration question. Five placebo-controlled trials with 536 participants in total set their primary assessment at four weeks, and the meta-analysis authors report substantial heterogeneity between trials together with a lack of long-term follow-up. Any fixed duration you are quoted is not coming from this evidence base.
How often is it repeated?
No standard interval follows from the sources on this page. The systematic review of masticatory-muscle changes reports dose-dependent denervation and recovery after atrophy that was incomplete in the studies reviewed, which is precisely why repeat timing is a clinical decision rather than a schedule. Bring the date and product name of any previous toxin injection to the consultation.
Who should not have this injection?
Botulinum toxin is contraindicated in people with known hypersensitivity to any botulinum toxin preparation or to the formulation components, and where there is infection at the proposed injection site. The labelling carries a boxed warning about distant spread of toxin effect and calls for caution in neuromuscular disorders such as myasthenia gravis, Lambert-Eaton syndrome and amyotrophic lateral sclerosis, and in people with swallowing or breathing difficulty. Pregnancy, breastfeeding, current medicines and prior toxin injections must be disclosed and reviewed.
Can it affect chewing, or make a smile uneven?
Both belong in the conversation, because this injection site is a working muscle. A 2026 systematic review of 14 studies — 2 in humans and 12 in animals — reports dose-dependent denervation and functional decline in masticatory muscles, and incomplete recovery after atrophy. The authors state that the human evidence is limited to two studies, so the size of the risk is not quantified. Report difficulty chewing, a changed bite or an uneven smile to the clinic rather than waiting it out.
Is masseter toxin FDA-approved?
No. The BOTOX Cosmetic label covers glabellar lines, lateral canthal lines, forehead lines and platysma bands; the masseter is not on it. On 2026-08-04 Allergan Aesthetics announced that the FDA had accepted a supplemental Biologics License Application for masseter muscle prominence, citing two phase 3 trials, M21-416 and M21-417, that met their primary endpoints (p=0.0046 and p=0.0014). Acceptance means the file entered review — no approval has been granted, and no action date was published.
How should I compare quotes between clinics?
Line up what each quote contains before comparing amounts: the product name, the dose in that product’s own units, whether the quote covers one side or both, how many injection points per side, whether a review visit or any adjustment is included, and whether it is one session or a package. Units are not convertible between brands, so two quotes built on different products are not measuring the same dose even when the numbers look similar.
Who is this for, and can I have it during a short trip?
Suitability is decided by an in-person assessment of the muscle, not from a photograph. The Korean indication wording for Nabota refers to adults aged 18 to 65 with marked to very marked benign masseter hypertrophy — a clinical grading, not a description of everyone who wants a narrower lower face. On a short trip, give your departure date so the clinician can agree in advance who reviews you if a symptom appears after you fly home.
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