What Is Jawline Slimming with Botox?
If your lower face looks broad or square, and you have wondered whether an injection could soften it, you are not alone. Many people in Tokyo ask whether “jaw Botox” is safe, how long it lasts, and whether it is even approved in Japan.
This guide explains how botulinum toxin is used to slim the jawline, what the published evidence says, and what to consider before booking.
What you’ll learn in this article:
- What masseter (chewing muscle) Botox is and how it changes the shape of the lower face
- Japan’s approval status for masseter treatment, including a recent change
- What studies suggest about results, duration and side effects
- Who may be a suitable candidate, and who should think twice
- Where to get jawline Botox in Tokyo with English-language support
Have a question about this treatment?
Message us on LINE or WhatsApp — our English-speaking team usually replies the same day.
The masseter muscle and the “square jaw”
The masseter is the thick muscle at the angle of the jaw that you use to chew. In some people it is enlarged, a condition called masseter hypertrophy, which can make the lower face look wider or more angular. Clenching and grinding the teeth can be one contributing factor.
Jawline slimming with botulinum toxin does not remove bone or fat. It targets the muscle only, so it suits a lower face that looks broad because of muscle rather than fat or bone.
Approval status in Japan
Botox Vista (Allergan Aesthetics, an AbbVie company) received an additional indication in Japan for the treatment of masseter hypertrophy in adults. A press release published on 27 August 2026 reports that approval was granted on 24 August 2026. Before this change, masseter treatment was outside the product’s listed indications, so older articles describing it as unapproved may be out of date.
Note that this approval applies to that specific product. Approval status, insurance coverage and self-pay (cosmetic) treatment are separate matters, and cosmetic jawline slimming is generally paid for out of pocket. Please confirm with the clinic which product will be used and how it is regulated.
How Jawline Botox Works
Botulinum toxin type A blocks the signal between nerve and muscle, so the injected muscle relaxes. When a muscle is used less, it can gradually become thinner, which may soften the contour of the lower face.
A doctor injects small amounts into the masseter, usually at several points on each side. A published review of the literature (Ferrillo et al., 2025) reports total doses of roughly 24 to 60 units for onabotulinumtoxinA or incobotulinumtoxinA products, and 60 to 300 units for abobotulinumtoxinA, which is measured on a different scale. Units are not interchangeable between brands, so the dose should be decided by your physician.
Expected Results and Duration
Results appear gradually rather than immediately, because the muscle needs time to weaken and slim. The same 2025 review describes effects lasting about 3 to 4 months, which is why the treatment is considered temporary.
In a randomized, triple-blind trial in 26 women (Nobre et al., Scientific Reports, 2024), 75 units of abobotulinumtoxinA were injected into each masseter. Muscle thickness decreased at 1 month after a single injection but had recovered by 3 months. Individual results vary, and no outcome can be guaranteed.
What People Often Get Wrong
Misconception 1: “Jaw Botox is off-label in Japan.”
This was true of earlier product labelling, but a masseter hypertrophy indication for Botox Vista was reported approved in August 2026. It is still worth asking which product your clinic uses.
Misconception 2: “More frequent injections simply keep shrinking the muscle, with no downside.”
In the trial above, the group given a repeat injection at 3 months still had reduced left masseter thickness at 6 months, and the authors reported sustained reductions in muscle electrical activity and impaired chewing performance. The study was small, but it suggests that repeated dosing deserves caution and that the schedule should be set with a physician.
Cost in Tokyo
Pricing depends on the product used and the number of units. Because prices change, we do not quote figures here. Please see the clinic’s official price page or contact us for a current quote.
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
Your doctor reviews your medical history and medications, examines the shape of your face and confirms that the width comes from muscle. Photographs are often taken for comparison.
During
The injections take only a few minutes. Injection-site pain is one of the most common effects.
After and possible side effects
The 2025 review summarises reported adverse effects by approximate frequency:
| Frequency | Reported effects |
|---|---|
| Common (about 30-50%) | Mild pain at injection sites; temporary muscle weakness |
| Occasional (about 2-15%) | Facial asymmetry, bruising, headache, altered chewing, sunken cheeks |
| Rare (about 0.2-2.3%) | Sagging of cheek or jaw soft tissue |
| Very rare (under 1%) | Immune-mediated reactions, speech disorders, swallowing difficulty |
These are pooled figures from a review, not a promise about any individual outcome.
Who Is a Good Candidate?
Adults whose lower face is broad mainly because of enlarged chewing muscles may be suitable, and a physical examination is the way to confirm this. The review notes that rapid masseter thinning can lead to skin laxity, particularly in older people or those with thinner skin. It also suggests caution with prolonged or high-dose use in the chewing muscles, because effects on the jawbone need further research.
People who have developed neutralizing antibodies to a botulinum toxin product may need an alternative formulation. Please discuss your full history at consultation.
Where to Get Jawline Botox in Tokyo
Within our clinic group, both BIOTOPE CLINIC (Shirokanedai, Minato-ku) and Kojimachi Dermatology & Plastic Surgery Clinic (Ichigaya, Chiyoda-ku) offer English-language consultation with Dr. Jun Karibe’s team. Jawline Botox is handled at BIOTOPE CLINIC in Shirokanedai. Bookings and enquiries in English: LINE or WhatsApp.
Botox injection is a treatment available at BIOTOPE CLINIC in Shirokanedai. Feel free to ask about it during a consultation with Dr. Karibe. Kojimachi Dermatology & Plastic Surgery Clinic focuses on insurance-covered dermatology and general plastic surgery.
Frequently Asked Questions
- Q. Is Botox for jawline slimming approved in Japan?
- A press release reports that Botox Vista received an additional indication for masseter hypertrophy in adults, approved on 24 August 2026. This applies to that product specifically, so please ask which product is used.
- Q. How long do the results last?
- A 2025 review describes effects lasting about 3 to 4 months. A small 2024 trial found muscle thickness had recovered by 3 months after a single injection.
- Q. Can jaw Botox affect chewing?
- Temporary muscle weakness and altered chewing are among the reported effects. The 2024 trial also reported impaired chewing performance with repeated injections, so the schedule should be planned with your doctor.
Have a question about this treatment?
Message us on LINE or WhatsApp — our English-speaking team usually replies the same day.
Summary
Botulinum toxin can slim a lower face that looks broad because of the masseter muscle, but the effect is temporary and varies between people. Japan’s approval status changed in August 2026, and evidence on repeated dosing suggests planning treatment carefully with a physician.
If you have questions about jawline slimming with Botox, both BIOTOPE CLINIC (Shirokanedai, Minato-ku) and Kojimachi Dermatology & Plastic Surgery Clinic (Ichigaya, Chiyoda-ku) offer English-language consultation with Dr. Karibe and his team. Jawline Botox is primarily handled at BIOTOPE CLINIC. English enquiries: LINE or WhatsApp.
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Book a Consultation or Treatment
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References
- Nobre et al. Exploring botulinum toxin’s impact on masseter hypertrophy: a randomized, triple-blinded clinical trial. Scientific Reports. 2024.
- Ferrillo M, Sommadossi E, Raciti L, et al. The Role of Botulinum Toxin for Masseter Muscle Hypertrophy: A Comprehensive Review. Toxins (Basel). 2025.
- Allergan Aesthetics (AbbVie). Allergan Aesthetics obtains additional indication approval in Japan for Botox Vista for masseter hypertrophy (press release, published via Nikkei Biotech Online). 27 August 2026.
- JAPIC. Botox Vista for Injection 50 Units, prescribing information database entry. Accessed September 2026.
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