Masseter Botox — PECHE Clinic, Gangnam Station
For a jawline squared by an overbuilt chewing muscle · 50-unit configuration · Right by Gangnam Station Exit 4
Masseter Botox
Masseter Botox places botulinum toxin into the chewing muscle (the masseter) — the one that hardens at the side of your jaw when you clench your molars — making that muscle work less. As the muscle rests, its bulk decreases, and the outer line of the lower jaw turns gentler.
▲ A vertical cross-section near the jaw's corner — beneath the thin epidermis, dermis, and yellow subcutaneous fat, the thick red layer is the chewing muscle (masseter), and the ivory at the bottom is the jawbone. The needle tip sits in the middle of the masseter, the teal tint is the spreading product, and the bone is untouched
The masseter starts beside the cheekbone and attaches at the jaw's corner — a thick muscle. Long-standing clenching or tooth-grinding builds it up, and the thicker it grows, the wider the lower face looks. Botulinum toxin reduces the signal telling the muscle to engage — and as the muscle rests, its bulk comes down.
When to Consider It
- Seen from the front, your lower jaw looks widened to the sides
- The side of your cheek hardens and juts when you bite down
- You have a clenching habit or grind your teeth
- You've lost weight, but your lower face's width hasn't changed
- The two sides of your jawline look different in thickness
If the squared look comes from the jawbone itself being wide, the angle remains even when the muscle shrinks. Whether the cause is muscle or bone is confirmed together during your assessment.
How the Muscle Gets Smaller
This treatment doesn't remove the muscle — it makes it rest. With less signal telling it to engage, the muscle is used less, and a muscle that goes unused loses bulk.
▲ Two cross-sections differing only in the masseter's thickness — on the left, the thick muscle bulges the outer skin line; on the right, the same muscle thinned, the line gentle. The ivory jawbone at the bottom is the same size in both
As the effect fades, you use the muscle again and its bulk returns. But areas treated over several rounds don't regain their former size, or regain it far more slowly — muscle builds less the longer it goes unused.
| Treatment area | The chewing muscle (masseter) beside the cheeks — both sides |
|---|---|
| Configuration | 50 units |
How It's Done
1. Assessment A 3D MetaVu scan captures your facial contours and left–right balance.
2. Muscle check You bite down while we feel where the muscle rises, checking the thickness and range on each side.
3. Dose decision From how developed the muscle is and the difference between sides, we set how much goes to each.
4. Numbing A cold roller dulls the sensation before we start.
5. Injection Divided doses go into several points within the muscle. Keeping the product from spreading to the nearby expression muscles — by depth and placement — is the heart of this treatment.
6. Aftercare guidance We go over what to follow for the day, including not lying down for 4–6 hours.
Results and Recovery
| Item | Details |
|---|---|
| Where it acts | The chewing muscle (masseter) beside the cheeks — below the fat layer |
| Amount per session | Around 50 units — a unit is the measure of the drug's amount · varies with muscle development and the difference between sides |
| When results show | Chewing force starts easing from days 3–7 and is clearest at week 2; the contour change emerges gradually after that — the signal doesn't cut off at once; it tapers over several days |
| How long it lasts | 3–6 months |
| Repeat cycle | 5–6 months or longer — we also look at when the reduced muscle begins to regain its bulk |
| Pain | A light sting as the needle enters; then, as the product spreads through the muscle, a deep, heavy, tingling pressure |
| Pain control | A cold roller dulls the sensation before we start |
| Downtime | The marks at the injection points settle within 1–2 hours; you can wash your face and wear makeup after 2–3 hours · bruises, if any, fade within 3–7 days |
| For the day | Don't lie down for 4–6 hours · skip saunas, hard exercise, and massaging the treated area — all to keep the product from spreading beyond where it was placed |
| What you may notice early on | During the first 2–3 weeks, when the effect peaks, your bite has noticeably less force on chewy foods — around a month in, the surrounding muscles adapt and it fades |
Expected Reactions and Possible Side Effects
Common, temporary reactions — part of the normal response:
- Marks at the injection points, settling within 1–2 hours
- Bruises, if any, fading within 3–7 days
- During the first 2–3 weeks, a weaker bite on chewy foods — fading as the surrounding muscles adapt, around a month in
Anything beyond this is uncommon. If a reaction lasts longer than expected or worsens, contact us and we'll check it with you.
What We Check Beforehand
If any of these apply to you, let us know during your consultation. We postpone or adjust the timing.
- Pregnancy or breastfeeding
- Conditions affecting the point where nerves meet muscles, such as myasthenia gravis — the very site where botulinum toxin acts, so symptoms could worsen
- Medications that affect nerve–muscle signaling (including some antibiotics)
- Jaw-joint pain, or difficulty opening your mouth — we check the condition first
- Cheeks already on the hollow side — reduced muscle can deepen the hollow look, so the dose is adjusted
- Inflammation or wounds at the injection site
- Aspirin or blood thinners (anticoagulants) — bruising can be heavier, so tell us in advance and we'll plan for it
- Botulinum toxin received elsewhere recently — tell us when, with which product, and how much, and we'll recalculate the total amount given in one session and the interval to your next treatment
How PECHE Clinic Does It
Each side gets its own dose. The two sides of a jaw often differ in thickness, and equal doses leave that difference in place. With the balance confirmed in your scan and standards built from over 90,000 treatments, we set how much goes to each side separately.
We offer four botulinum toxin products. Botulinum toxin is a substance produced by bacteria. The bacteria send it out wrapped in other proteins to keep it intact — but only the core inside produces the effect; the wrapping plays no part in it. The core is identical across all four products; what differs is that some products keep the wrapping, and some strip it away to leave only the core.
| Product | Made by | Protein wrapping | Albumin (storage aid) |
|---|---|---|---|
| Newlux | Medytox, Korea | Kept | Used |
| Coretox | Medytox, Korea | Stripped away | Not used |
| Xeomin | Merz, Germany | Stripped away | Used |
| Allergan Botox | AbbVie, USA | Kept | Used |
What keeping or stripping the wrapping means. The wrapping protects the core — but it also means foreign proteins unrelated to the effect enter your body along with it. Repeated over the years, your body can come to recognize and respond to those proteins — and then the same dose may not work as well as it once did. Stripped products leave less room for that. For a one-off treatment the difference is negligible; it matters when you plan to continue over several years.
Albumin is a common protein naturally present in human blood. It keeps the core from degrading while the drug is stored as a dried powder — and Coretox does without it too. The masseter isn't a one-session area — it's repeated in half-year rounds, with a larger dose per session than treatment for expression lines — so we look at how many years you plan to continue, together with the product.
We open the genuine product in front of you — and you can watch it being dissolved through the glass wall, too. Botulinum toxin doesn't keep long once dissolved, so it's stored as a powder and dissolved in saline just before treatment. The more diluted it is, the larger its volume — and the wider it spreads. With around 50 units going in at once, what was dissolved and in what amount directly shapes the result. You see which product is opened right in front of you, and the dissolving itself is visible through the glass wall from the waiting area.
▲ The prep room, seen through the glass from the waiting area — which product is dissolved, and how much, is visible through this glass
If the bone is the cause, we say so. If the squared look comes from the width of the jawbone rather than the muscle, this treatment won't change it as much as you'd hope. In that case we tell you the expected range of change first, and let you decide. You're welcome to come in just for a consultation.
▲ The 3D MetaVu screen — contours and balance are captured before treatment, turning the difference between your two jawlines into values rather than impressions
Pricing
Masseter Botox is offered in a 50-unit configuration; the cost varies with the product used. We check the muscle's condition during your assessment, then give you a quote.
Location
PECHE Clinic 3F, 364 Gangnam-daero, Gangnam-gu, Seoul Right in front of Gangnam Station, Exit 4
The next dose is recalibrated from your first round's result — so an easy trip back for the progress check genuinely matters.
FAQ
Q1. Who performs the treatment? A: PECHE physicians who all work to the same injection standards, built from over 90,000 documented treatments. The smiling muscles run right beside the masseter, and a misplaced depth or point can leave expressions awkward — so the per-side dose and injection points are set by these standards, not by feel.
Q2. When will my jawline change? A: Chewing force starts easing from days 3–7, but the visible contour change needs the resting time to accumulate — it emerges gradually over several weeks. The first round's change can feel modest, growing clearer as the resting time builds.
Q3. Will chewing be uncomfortable? A: During the first 2–3 weeks, when the effect peaks, your bite has noticeably less force on chewy foods; around a month in, the surrounding muscles adapt and it fades. It doesn't stop you eating — and not placing more than needed is how that feeling is kept small, so we start with the minimum.
Q4. Won't my cheeks look hollow? A: As the muscle's bulk comes down, the skin and fat that covered it can stand out more, and the cheeks can look hollower. If your cheeks are already thin, we reduce the dose or point you to a different approach first — we check this possibility together before starting.
Q5. What should I look for when choosing a clinic? A: Whether they first confirm if the cause is muscle or bone, and whether they assess each side separately. Skip those two, and you can end up with the thickness difference remaining — or getting treated when the cause wasn't muscle at all.