What causes a square jaw?

A wide, square lower face has several possible causes. The most common one that clinics can treat is an enlarged masseter, the chewing muscle at the angle of the jaw. It grows larger with genetics, teeth clenching or grinding (bruxism), and habits such as chewing gum or tough foods. Other causes include the shape of the jaw bone itself, fat along the lower face and early jowls. Masseter enlargement is often uneven, so one side may look wider than the other, and clenching can also cause jaw fatigue or tension headaches. In Korea, softening a square jaw into a slimmer, V-shaped lower face is one of the most common non-surgical requests.

How a square jaw is assessed

At Dernia Clinic Myeongdong, your doctor feels the masseter while you clench and relax, and looks at your face from the front and side. This shows whether the width comes mainly from:

Muscle: a firm bulge that hardens when you clench, which responds to Botox
Bone: a wide jaw angle that Botox cannot change
Soft tissue: fat or jowls along the jaw, which need lifting or fat reduction

Your doctor also asks about clenching, grinding, jaw pain and headaches, since these affect the plan and the dose. Photos from several angles help compare the two sides and track the change over the coming weeks.

Treatment options for a square jaw

Jaw (Masseter) Botox

Jaw Botox relaxes the masseter muscle so it gradually becomes smaller, slimming the lower face. It is the first choice when muscle is the main cause. The injections take about 10 minutes, slimming appears over about 4–8 weeks, and results last about 4–6 months. It can also ease clenching. Because the masseter needs a larger dose than most areas, many people choose a Korean toxin to keep costs down, though imported brands are available. The dose depends on your muscle size; read how many units of jaw Botox you need.

Shurink Universe

Shurink Universe is Korean HIFU that tightens the soft tissue along the jaw and under the chin. It does not shrink muscle or bone, but it sharpens the jawline as the tissue tightens over a few weeks. Your doctor chooses it when mild laxity or soft tissue blurs the jaw, often alongside Botox. A session takes about 20–40 minutes with no downtime, and results last about 3–6 months, so it is often repeated.

Comparing your options

Treatment	Best when	Downtime	From price
Jaw (Masseter) Botox	Muscle causes the width	None	₩59,000 (both sides, Korean toxin)
Shurink Universe	Soft tissue blurs the jawline	None	₩149,000 (300 shots)

Prices are in Korean won (KRW), exclude 10% VAT, and are confirmed at your consultation. You can compare every treatment on our price list.

Combination plans

Many people combine jaw Botox with HIFU for a slimmer, more defined lower face in one visit, and energy devices are usually done before injections. Our V-Line Contour package adds fat-dissolving injections for fullness under the chin. If fat rather than muscle is the issue, read jaw Botox vs fat-dissolving injection. See all options on our jawline and V-line page.

At-home care and prevention

Cut down on gum and very chewy foods, notice daytime clenching, and ask your dentist about a night guard if you grind your teeth. Stress can increase clenching, so relaxation and good sleep help too. After Botox, avoid massaging the jaw or lying face down for a few hours, as your doctor advises.

Planning treatment during a trip to Seoul

Jaw Botox has no downtime, so you can sightsee straight away and fly the next day. Because slimming takes several weeks, you will see the change at home. Chewing may feel slightly weaker for a few weeks, which is normal. Take a photo before treatment so you can compare the change in a month or two. Book a consultation to have your jaw assessed.

Safety and when to see a doctor

Jaw Botox is not given during pregnancy or breastfeeding, or to people with certain neuromuscular conditions. Too high a dose can cause chewing fatigue or, in some faces, a hollow look below the cheekbones, so doses are kept conservative. Tell your doctor if you have had jaw Botox elsewhere recently. Jaw pain, clicking, locking or frequent headaches may be a jaw joint (TMJ) problem and should be checked by a dentist or doctor.

How long does jaw Botox take to work?

The muscle starts to relax within a week or two, but visible slimming usually appears over about 4–8 weeks as the muscle becomes smaller.

How long do jaw Botox results last?

Usually about 4–6 months. With repeated treatments, some people find they need top-ups less often.

Will jaw Botox affect my chewing?

Chewing hard foods may feel a little weaker for a few weeks. Everyday eating is not affected, and the feeling fades as you adjust.

Can Botox change the shape of my jaw bone?

No. Botox only slims the muscle. If the width comes from bone, Botox will have a limited effect, and your doctor will explain this honestly.

Can I have jaw Botox and HIFU on the same day?

Yes. They are commonly combined, and your doctor will decide the order. Both have little or no downtime.

Related treatments

Jaw (masseter) Botox — slims the chewing muscle
Shurink Universe — sharpens the jawline
Fat-dissolving injection — for fat along the jaw

Prices, results and reviews

Jaw Botox price — cost for both sides
Jaw Botox results — slimming timeline
Jaw Botox review — our medical team’s assessment

Related concerns and areas

Double chin — fullness under the jaw
Jowls — sagging along the jawline
Jawline and V-line — all jawline options

Packages and FAQs

V-Line Contour package — Botox, HIFU and fat reduction
How many units of jaw Botox? — dosing explained

Dernia Clinic Myeongdong

Square Jaw Slimming in Seoul