Jawline Slimming Botox in Tokyo: How It Works, Results, Cost and Safety
A square or wide lower face can make you feel self-conscious in photos, even when the rest of your features feel balanced.
When that width comes from the chewing muscles, jawline slimming Botox is one of the least invasive ways to soften it. If you are considering the treatment in Tokyo, it helps to know what the evidence shows, what Japan’s regulations now say, and what you will pay.
This guide covers how masseter Botox works, what clinical trials report, current prices at our clinic group, and who should and should not have the treatment.
What you’ll learn in this article:
- What jawline slimming (masseter) Botox is, and its approval status in Japan as of 2026
- What clinical trials report about results, onset and duration
- Current published prices for masseter Botox at our Tokyo clinic group
- Possible side effects and what to expect before, during and after treatment
- Who is a suitable candidate and who should avoid the treatment
Have a question about this treatment?
Message us on LINE or WhatsApp — our English-speaking team usually replies the same day.
What Is Jawline Slimming Botox?
Jawline slimming Botox is an injection of botulinum toxin type A into the masseter muscles. These are the main chewing muscles, found at the back corners of the jaw. When they are well developed, they can make the lower face look wide or square. The medical term for this is masseter muscle prominence, often shortened to MMP.
In everyday Japanese it is often called “era Botox” (era refers to the angle of the jaw). You may also see it called masseter Botox, jaw Botox or face-slimming Botox.
Approval status in Japan (updated August 2026)
Masseter treatment used to be off-label in Japan. That changed in August 2026, when the Japanese package insert for Botox Vista (AbbVie) was revised to add “masseter muscle prominence in adults under 65” as an approved indication.
The package insert is the official prescribing document published through Japan’s Pharmaceuticals and Medical Devices Agency (PMDA). The same revision approved a new 100-unit vial. The approved dose is a total of 48–72 units, split equally across three points in each masseter (six in total), with no repeat treatment within three months.
This approval applies only to that specific product. Other botulinum toxin products, including Korean-made ones, have not been approved in Japan. Approval of a product’s indication also does not by itself mean the treatment is covered by National Health Insurance.
How It Works and Expected Results
Botulinum toxin temporarily blocks the nerve signals that tell a muscle to contract. When the masseter is used less, it gradually becomes less bulky. That can narrow and soften the lower face. The treatment does not remove fat, skin or bone. It acts only on the muscle.
What the clinical trials showed
Clinical reports indicate a meaningful effect compared with placebo (a dummy injection). A Phase 3, randomised, placebo-controlled trial published in the Aesthetic Surgery Journal enrolled 376 adults at 21 sites in China, Canada and Taiwan. The participants all had marked or very marked masseter prominence. Each received 72 units of onabotulinumtoxinA (the active ingredient in Botox) or a placebo.
- At Day 90, 51.2% of treated participants improved by at least two grades on a five-point masseter prominence scale, compared with 2.2% on placebo.
- Average lower-face width fell by 5.24 mm in the treated group, compared with 0.04 mm on placebo.
- The benefit over placebo was significant at the first check (Day 30) and still present at Day 180.
The Japanese trial behind the 2026 approval (jRCT2031230467) used the same kind of scale. It counted a patient as improved if they dropped two grades or more. At Day 90, 40.9% of the 48-unit group and 39.4% of the 72-unit group improved, compared with 0% on placebo. These figures show that results vary considerably from person to person. The treatment is not guaranteed to produce a visible change in everyone.
How long it lasts
In the multiregional trial, the effect lasted up to six months. Botox pages at our clinic group describe a typical duration of about four to six months, with individual variation. Under the Japanese package insert, repeat injections should not be given within three months.
Common Misconceptions About Masseter Botox
“It will slim any wide face”
The treatment targets muscle, so it only helps when muscle is what makes the face wide. The trials enrolled only adults whose masseters were rated as markedly prominent. If your jaw width comes mainly from bone structure, fat or sagging skin, Botox is unlikely to address it. An in-person assessment is the only reliable way to tell.
If fullness along the jawline seems to be fat or skin laxity rather than muscle, a doctor may discuss other options such as fat-dissolving injections or HIFU (high-intensity focused ultrasound for skin tightening). These are treatments available at BIOTOPE CLINIC in Shirokanedai. Feel free to ask about them during a consultation with Dr. Karibe.
“Botox units are the same whatever the brand”
They are not. The Japanese package insert for Botox Vista states that its units are specific to that product and cannot be converted to those of other botulinum toxin products. When you compare prices by unit count across brands, you are not comparing like with like.
“Masseter Botox is known to weaken the jawbone”
The evidence is mixed, so it is best not to dismiss or overstate this concern.
A 2019 review in Toxins found that animal studies consistently showed jawbone loss after botulinum toxin in the chewing muscles. Human evidence was limited, and the review advised telling patients about the possible risk. More recently, a 12-month, placebo-controlled CT study of 123 adults found no clinically significant change in jawbone density. Participants received 48, 72 or 96 units, once or twice. Long-term data on many repeated treatments are still limited.
Cost of Jawline Slimming Botox in Tokyo
The prices below come from the clinic group’s current public price list (tax included). Unit counts are shown as listed. Because units differ between products, the two options should not be compared unit for unit.
| Option | Regulatory status in Japan | Masseter 60 units | Masseter 100 units |
|---|---|---|---|
| Allergan-made botulinum toxin | Manufacturer’s Botox Vista is approved for masseter prominence (since August 2026); ask which product will be used | ¥35,000 | ¥68,000 |
| Korean-made botulinum toxin | Authorised by the Korean regulator; not approved in Japan (imported by the clinic through import procedures) | ¥29,800 | ¥45,000 |
The price list also shows a first or return visit fee of ¥3,300 and states that anaesthesia is charged separately at ¥2,200. The dose suited to you depends on your muscle size and the product used, and a doctor decides it at consultation. Prices can change, so please see the clinic’s official price page for the latest figures. For an accurate quote, please book a consultation.
Have a question about this treatment?
Message us on LINE or WhatsApp — our English-speaking team usually replies the same day.
What to Expect: Before, During and After
Before
The doctor checks whether your jaw width is actually due to the masseter. They usually do this by feeling the muscle while you clench your teeth. Tell the doctor about any pregnancy or breastfeeding, neuromuscular conditions, current medicines (especially aminoglycoside antibiotics or muscle relaxants) and any recent botulinum toxin treatment.
During
Under the Japanese approved method, the toxin is injected at three points in each masseter. The procedure itself is brief and involves a few small injections.
After
Our clinic group lists the following possible effects. Redness, swelling and bruising usually settle within a few days. Mild pain or an odd sensation, left–right asymmetry and allergic reactions can also occur. Botox generally starts to take effect within two to three days. The slimming itself is assessed over the following weeks and months, which is why trials measured it at Day 30, Day 90 and beyond.
Side effects specific to the masseter were uncommon in trials, but they did occur.
- Chewing difficulty: 4.2% of treated participants in the multiregional trial (0% on placebo); 1.9% in the Japanese 72-unit group.
- Muscle fatigue: 1.9% in both Japanese dose groups.
- Paradoxical bulging (a part of the muscle bulging unexpectedly): 2.1% in the multiregional trial; 1.9% in the Japanese 48-unit group.
Rarely, the toxin’s effects can spread beyond the injected muscle. The Japanese package insert notes reported cases of swallowing difficulty, pneumonia and severe weakness, including deaths, with botulinum toxin products. Seek medical care promptly if you develop difficulty swallowing, speaking or breathing. The insert also notes that repeated treatment can lead to antibody formation, which may reduce the effect over time.
Who Is a Good Candidate?
Suitable candidates are generally adults whose lower-face width is caused by prominent masseter muscles and who understand that results vary and are temporary. The Japanese approval covers adults under 65. The package insert states that treatment is not recommended for people aged 65 or over.
Who should avoid it
Under the Japanese package insert, Botox Vista must not be given to:
- People with generalised neuromuscular junction disorders, such as myasthenia gravis
- People who are pregnant, may be pregnant, or are breastfeeding
- People with a history of hypersensitivity to any ingredient of the product
- People currently being treated with another botulinum toxin product
The package insert also advises contraception during treatment. Women should continue it until two menstrual cycles have passed after the last dose, and men for at least three months. Our clinic group does not give Botox to anyone who is pregnant or breastfeeding.
Where to get jawline slimming Botox in Tokyo
Within our clinic group, both BIOTOPE CLINIC (Shirokanedai, Minato-ku) and Kojimachi Dermatology & Plastic Surgery Clinic (Hirakawacho, Chiyoda-ku) offer English-language consultation with Dr. Jun Karibe’s team. Dr. Karibe is a board-certified plastic surgeon certified by the Japan Society of Plastic and Reconstructive Surgery. Jawline slimming Botox is handled at BIOTOPE CLINIC (Shirokanedai), one minute from Shirokanedai Station. Bookings and enquiries in English: LINE or WhatsApp.
Frequently Asked Questions
- Q. Is jawline slimming Botox approved in Japan?
- Yes, for one product. In August 2026, Botox Vista’s Japanese package insert was revised to include masseter muscle prominence in adults under 65. Other botulinum toxin products, including Korean-made ones, have not been approved in Japan.
- Q. How soon will my face look slimmer?
- Botox usually starts working within a few days, but the slimming develops over the following weeks. In the multiregional Phase 3 trial, the difference from placebo was already significant at the first check on Day 30, and the main assessment was at Day 90.
- Q. How long does it last, and how often can I repeat it?
- In the multiregional trial, the effect lasted up to six months. The Japanese package insert advises against repeating treatment within three months.
- Q. Will it affect my chewing?
- Some people notice chewing difficulty or jaw fatigue. In trials, this affected roughly 2–4% of treated participants. These effects were mostly mild and resolved on their own in the multiregional trial.
- Q. Can I have it while pregnant or breastfeeding?
- No. Pregnancy, possible pregnancy and breastfeeding are contraindications under the Japanese package insert, and our clinic group does not give Botox in these situations.
Have a question about this treatment?
Message us on LINE or WhatsApp — our English-speaking team usually replies the same day.
Summary
Jawline slimming Botox relaxes the masseter muscles to soften a wide or square lower face.
As of August 2026, Botox Vista is approved in Japan for this use in adults under 65, at 48–72 units per session. Trials report clear improvements compared with placebo, lasting up to about six months. Results vary between individuals, and chewing difficulty or uneven bulging can occur. Evidence on long-term effects on the jawbone is still developing.
If you have questions about jawline slimming Botox, both BIOTOPE CLINIC (Shirokanedai, Minato-ku) and Kojimachi Dermatology & Plastic Surgery Clinic (Hirakawacho, Chiyoda-ku) offer English-language consultation with Dr. Karibe and his team. Jawline slimming Botox is primarily handled at BIOTOPE CLINIC (Shirokanedai). English enquiries: LINE or WhatsApp.
24/7 Consultation & Booking
Book a Consultation or Treatment
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References
- Sun J, Wang L, Wu Y, et al. OnabotulinumtoxinA Treatment for Masseter Muscle Prominence: 6-Month Safety and Efficacy Results, Including Patient-Reported Outcomes, From a Phase 3, Randomized, Placebo-Controlled, Multiregional Trial. Aesthetic Surgery Journal. 2025;46(5):486–494.
- AbbVie GK. Botox Vista for Injection 50 Units / 100 Units (A-type botulinum toxin), Japanese package insert, revised August 2026 (4th edition). Pharmaceuticals and Medical Devices Agency (PMDA). https://www.pmda.go.jp/
- Kostenuik P, et al. Longitudinal Computed Tomography Indicates No Negative Impact of OnabotulinumtoxinA on Mandibular Bone Density in a 12-Month, Double-Blind, Randomized, Repeat Treatment, Placebo-Controlled Study in Healthy Adults With Masseter Muscle Prominence. Aesthetic Surgery Journal. 2025;46(1):76–85.
- Balanta-Melo J, Toro-Ibacache V, Kupczik K, Buvinic S. Mandibular Bone Loss after Masticatory Muscles Intervention with Botulinum Toxin: An Approach from Basic Research to Clinical Findings. Toxins. 2019;11(2):84.
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