In Japan, the phrase 小顔になりたい (I want a small face) is practically a national motto. Walk through any Harajuku or Omotesando clinic and you'll see masseter Botox listed as casually as teeth cleaning at a dentist. It's that normalized here. But for foreigners, there's a lot of confusion: how many units do you actually need? Why is it so cheap in Japan? And why did a Tokyo clinic just tell me I'm "too old" for this?
This guide covers everything. For general Botox in Japan (forehead, crow's feet, all areas) and Botox in Tokyo specifically, we have separate guides. This one is specifically about masseter — jaw slimming — because it deserves its own conversation.
How It Works (30-Second Version)
Your masseter is the muscle you use to chew. If it's overdeveloped — from genetics, teeth grinding, gum chewing, or just stress — your jawline can appear wider and more square. Botox is designed to temporarily reduce muscle activity. Over 4–6 weeks, the treated muscle typically decreases in size from reduced use, which may result in a slimmer-looking jaw.
It's also commonly used to help manage teeth grinding (bruxism), jaw clenching, and TMJ discomfort. According to HADA NO CLINIC's published treatment protocol, weakening the masseter muscles can reduce the burden on the back teeth and may improve sleep quality. Many patients come for the slimming and stay for the functional benefits.
How Many Units Do You Actually Need?
This is where clinics play games. Some advertise "jaw Botox from ¥8,000!" but that's often for 10–20 units, which is unlikely to produce visible slimming. Based on dosage guidelines published by clinics like HADA NO CLINIC and BIANCA Clinic, here's a more realistic breakdown:
| Muscle Size | Units Per Side | Total Units | Expected Cost |
|---|---|---|---|
| Mild (slight squareness) | 20–25 | 40–50 | ¥20,000–50,000 |
| Moderate (visible bulk) | 25–35 | 50–70 | ¥30,000–65,000 |
| Severe (teeth grinder, very square) | 35–40 | 70–80 | ¥40,000–80,000 |
Key: If a clinic offers jaw slimming for under ¥20,000 and doesn't tell you the unit count, ask. According to published protocols, fewer than 40 units total is generally considered insufficient for noticeable slimming. Japanese phrases to use: 何単位入れますか？ (How many units will you inject?) and 両側で何単位ですか？ (How many units for both sides?)
Price Comparison by Clinic Type
| Clinic Type | Brand | 50 Units | 80 Units | Note |
|---|---|---|---|---|
| Budget chain (SBC, TCB) | Korean Botox | ¥8,000–25,000 | ¥15,000–40,000 | Cheap but non-MHLW approved brands |
| Mid-range (Elm, Hada no) | Coretox / Botox Vista | ¥25,000–45,000 | ¥40,000–65,000 | Good value + approved products |
| Premium (BIANCA, Azabu) | Allergan Botox Vista | ¥40,000–55,000 | ¥55,000–80,000 | English + MHLW-approved only |
Botox Vista vs Korean Botox: Allergan's Botox Vista is the only MHLW-approved botulinum toxin in Japan. Korean alternatives (Coretox, Nabota, Innotox) are more affordable and widely used at many clinics, though they have not received MHLW approval. Both are reported to be effective by practitioners, though onset time and duration may vary slightly. Individual results depend on the practitioner's technique as much as the product. For full brand comparison, see the Botox Japan guide.
The 40+ Warning Nobody Mentions
If you're over 40, read this carefully.
Shrinking the masseter muscle removes volume from your lower face. In your 20s–30s, skin elasticity generally compensates. In your 40s+, reduced muscle bulk may cause the overlying skin to sag — potentially trading a square jaw for jowls.
This isn't speculation. HADA NO CLINIC in Tokyo explicitly states on their website that they do not recommend masseter Botox for patients in their 40s and beyond, citing the risk of skin laxity from muscle volume loss.
Possible alternatives for 40+: Combining with thread lift or HIFU may help tighten the skin simultaneously. A lower dose (30–40 units) may provide muscle relaxation without dramatic volume loss. Consult your doctor about which approach suits your anatomy.
Jaw Botox for Teeth Grinding (Bruxism)
This is the medical side that makes jaw Botox more than cosmetic. If you grind your teeth at night, your masseter may be overworking constantly. The muscle can grow larger (potentially widening your jawline) while your teeth suffer from the pressure. Botox is intended to reduce muscle activity, which in turn may decrease grinding force, lower the risk of tooth damage, ease jaw pain, and — as many patients report — improve sleep quality.
Many foreigners in Tokyo discover this treatment because their Japanese dentist suggests it — not a cosmetic surgeon. It's that mainstream here. Insurance doesn't cover it in Japan (classified as cosmetic), but the functional benefit is widely recognized by practitioners. If you're already considering dental work in Japan, it's worth asking your dentist about masseter Botox as a complementary option.
Jaw Botox vs V-Line Surgery
Jaw Botox
Muscle only · 20 min · No downtime · Repeat every 4–6 months · Non-surgical
V-Line Surgery
Bone + muscle · 2–4 hours · 4–6 weeks recovery · Permanent · General anesthesia
How to tell which you might need: Clench your teeth and feel your jaw. If the sides bulge outward when you bite down — that's likely muscle. Botox may help reduce it. If your jaw is wide even when fully relaxed — that's more likely bone structure. Only surgery can reshape bone. A qualified clinic will assess this during consultation. If they push Botox on what appears to be a bone issue, consider getting a second opinion.
The Korea vs Japan comparison is relevant here: V-line surgery is a Korean specialty (₩2M–5M, much cheaper than Japan). For bone work, Seoul might make more sense. For muscle slimming, Japan's Botox pricing and quality are excellent.
Where to Get Jaw Botox in Tokyo
BIANCA Clinic (Ginza & Omotesando) — Full facial assessment including bite alignment before injection. English-speaking. Uses Botox Vista only. Combines with fillers and threads if needed. Documents injection sites and units for perfect repeat sessions.
HADA NO CLINIC (Koenji) — Uses Coretox. Very detailed about dosage: minimum 50 units, recommends 80 for heavy grinders. Adjusts left/right asymmetry. Won't treat 40+ patients for slimming (honest). English website.
Azabu Skin Clinic (Azabu) — Dr. Kawashima speaks English. Also does jaw Botox for TMJ, bruxism, and gummy smile correction. Can combine with forehead Botox same session.
Elm Clinic (Omotesando + 8 locations) — Offers "Elabotox" jaw slimming packages. Multiple sessions at reduced rates. Also does skin treatments and thread lifts.
TCB / SBC — Cheapest per-unit pricing. Good for first-timers who want to test with 40–50 units before committing. Limited English. Tokyo clinic guide has more details on chain clinics.
Smart Combos: Jaw Botox + What Else?
| Combo | Why | Same Day? | Guide |
|---|---|---|---|
| Jaw + forehead Botox | Most common combo, one visit | Yes | Botox Japan |
| Jaw + chin filler | Slim jaw + defined chin = V-line without surgery | Yes | Fillers |
| Jaw + thread lift (40+) | Prevent sagging from muscle loss | Same week | Thread Lift |
| Jaw + HIFU | Skin tightening + muscle slimming | 2 weeks apart | Face Lifting |
| Jaw + nose filler | Slimmer jaw makes nose look more prominent | Yes | Nose Job Tokyo |
The jaw + chin filler combo is basically a non-surgical V-line. Takes 30 minutes, costs ¥50,000–120,000 total, and the visual change is dramatic. This is one of the most popular combination treatments at Tokyo clinics.
The Maintenance Game
First session: you'll see results at week 4, it fades around month 5. Second session (month 3–4): the muscle is already partially atrophied, so less units might work. Third session: the muscle has been weakened enough that some patients can extend to 6–12 months between sessions. After 3–4 sessions, some people stop entirely — the muscle stays slim because it "forgot" how to be big.
Budget for 3 sessions in year 1 (¥75,000–240,000 total), then 1–2 per year after that. Over 3 years, you'll spend less than one V-line surgery.
Pro tip from Tokyo clinics: If you're coming to Japan specifically for this, schedule your first session at the start of your trip and a follow-up appointment 2 weeks later. Some clinics offer a "touch-up" where they inject a few extra units into areas that didn't respond evenly. BIANCA and HADA NO CLINIC both record your exact injection sites and unit counts, so repeat sessions — even months later — are precisely calibrated. Ask: 施術記録を残してもらえますか？ (Can you keep a record of my treatment?)
FAQ
How much does jaw Botox cost in Japan?
¥25,000–80,000 per session depending on units (50–80) and brand. Budget chains from ¥8,000 but with fewer units and non-approved brands.
How many units do I need?
Minimum 50 (25 per side). Heavy grinders: 80 (40 per side). Under 40 units won't produce visible slimming.
How long does it last?
4–6 months. After 2–3 repeat sessions, intervals extend to 6–12 months as muscle atrophies.
Is it safe if I'm over 40?
Risky without skin tightening. Reduced muscle volume can cause lower face sagging. Combine with thread lift or HIFU, or use lower dose.
Does it help with teeth grinding?
Yes. Primary medical use. Reduces grinding force, jaw pain, TMJ symptoms, and tooth damage. Many patients report better sleep.
Botox or V-line surgery?
Clench your jaw. Sides bulge = muscle → Botox. Wide when relaxed = bone → surgery. Botox ¥25K–80K/session. V-line ¥1.5M–3M permanent.
Related Guides
Sources & references: Pricing and dosage information in this guide is based on publicly available data from clinic websites including HADA NO CLINIC, BIANCA Clinic, TCB, and Elm Clinic, accessed March 2026. Prices and protocols may change; verify directly with your chosen clinic before booking.
Medical disclaimer: This content is for informational purposes only and does not constitute medical advice, diagnosis, or treatment. Individual results vary. Always consult a qualified medical professional before undergoing any cosmetic procedure. ClinicJapan is an independent guide and is not affiliated with any clinic mentioned.