Concern

What causes a square jaw?

A square or wide jawline is not one condition but an appearance with several possible causes. Identifying which one applies to you determines whether a non-surgical treatment can help.

Masseter hypertrophy: the chewing muscle at the angle of the jaw becomes enlarged, often from clenching, grinding (bruxism), chewing gum or hard foods.
Lower-face fat: soft fullness along the jawline and cheeks that adds width.
Sagging and jowls: descending tissue that blurs the jaw contour and makes the lower face look heavier.
Bone structure: a naturally wide or prominent mandible, which injections and devices cannot change.

Many people have more than one factor. For example, someone in their 30s may have a strong masseter as well as early jowl formation.

How do you tell if a square jaw is muscle or bone?

A simple self-check is to place your fingertips at the angle of your jaw and clench your teeth. If a firm bulge pushes outward, the masseter is likely contributing. If the angle feels hard and wide even when relaxed, bone structure may play a larger role.

At Re:berry Hongdae, the doctor assesses this more precisely by palpating the muscle at rest and when clenched, looking at your face from several angles, checking fat thickness and skin laxity, and asking about clenching, grinding and jaw discomfort. This diagnosis comes before any treatment recommendation.

Which Re:berry treatments are used for a square jaw?

Jaw Botox for masseter-related width

Jaw Botox, also called masseter reduction, uses a botulinum toxin injection to relax the muscle. With less activity, the muscle gradually becomes smaller, which can narrow the lower face. Some people also notice less clenching. The injection itself takes only a few minutes.

ONDA and contour injections for fat

Where fat rather than muscle is adding fullness, ONDA Face Lifting uses microwave energy to target fat and tighten skin. Re:berry's Berry Slim contour injection is sometimes paired with ONDA for localized fat.

Lifting for sagging-related heaviness

If jowls are blurring the jawline, ultrasound or radiofrequency lifting such as Ultherapy Prime, Thermage FLX or Sofwave, or thread lifting, may be considered.

Why combine treatments for jawline shaping?

Slimming the masseter alone can make sagging more visible in some people, especially after their mid-30s, because the muscle was providing some support. Combining muscle relaxation with skin tightening or fat reduction can give a more balanced contour. The doctor will explain the sequence, for example jaw Botox first, then lifting several weeks later once the muscle has started to reduce.

What is the timeline for jaw slimming?

Days 3–7: chewing may feel slightly weaker as the toxin starts to work.
Weeks 2–4: the muscle begins to soften; changes are subtle.
Weeks 4–8: visible slimming often appears in photos and from the front.
Months 3–6: the effect gradually fades as muscle activity returns; repeat treatment is planned.

With regular sessions, many people find the muscle stays smaller for longer and they need treatment less often. Results vary by individual. See how long jaw Botox takes to slim the face for more detail.

What are the side effects and precautions?

Side effects of jaw Botox are usually mild: small injection marks, bruising, temporary chewing fatigue and, occasionally, an uneven smile if the toxin spreads to nearby muscles. Over-treatment can cause hollowing below the cheekbones in some faces. Botulinum toxin is not recommended during pregnancy or breastfeeding, or for people with certain neuromuscular conditions. Tell the doctor about medications and any previous toxin treatments.

What lifestyle habits make a square jaw worse?

Because the masseter is a muscle, how you use it affects its size. Habits that keep it working hard can make it bulkier over time and may shorten how long jaw Botox lasts.

Clenching during concentration, stress or exercise
Night-time grinding, sometimes noticed as morning jaw ache or tooth wear
Frequent gum chewing or a diet of hard, chewy foods such as dried squid or jerky
Chewing mainly on one side, which can create asymmetry

Small changes, such as noticing daytime clenching or asking a dentist about a night guard, can support the results of treatment.

How does a square jaw differ from a double chin or jowls?

These concerns often overlap but are diagnosed separately. A square jaw is width at the jaw angle seen from the front. A double chin is fullness under the chin and along the neck, usually fat or laxity. Jowls are descended tissue that breaks the line of the jaw near the mouth. A face may have all three, and each calls for a different tool, which is why Re:berry designs a combination plan instead of a single procedure.

Is square jaw treatment suitable for visitors to Hongdae?

Jaw Botox is popular with travelers because the injection is quick and downtime is minimal. However, the slimming appears weeks later, often after you have returned home, so plan your follow-ups accordingly. You can read the dedicated jaw Botox for square jaw guide. Pricing depends on the product, dose and combination, and is confirmed in writing at consultation. Book via our Booking page.

Can jaw Botox change my bone structure?

No. Jaw Botox relaxes and gradually shrinks the masseter muscle, but it cannot alter the shape or width of the jawbone. If your jaw width is mainly due to bone, injections may produce little change, and the doctor will explain this during the consultation.

Will jaw Botox affect my chewing?

Many people notice mild chewing fatigue with tough or chewy foods for a few weeks after treatment. Normal eating is generally not affected. This usually improves as you adapt and does not prevent everyday meals, though some people choose softer foods at first.

Can jaw Botox help teeth grinding?

Relaxing the masseter muscle may reduce clenching and grinding for some people, which is why it is sometimes used for bruxism-related discomfort. It does not treat the underlying cause, and dental assessment may still be recommended for jaw joint or tooth wear issues.

Can a slimmer jaw make my face look saggy?

In some people, especially with thinner skin or early laxity, reducing masseter bulk can make sagging more noticeable. This is why the doctor assesses skin quality first and may suggest combining jaw Botox with lifting or tightening treatments for a balanced result.