Quick answer: Masseter Botox slims the lower face by relaxing and gradually shrinking the chewing muscles at the corners of the jaw. You will feel chewing get weaker within one to two weeks, see slimming from about four weeks, and reach the peak at two to three months. Results usually last four to six months and often longer after repeat sessions.
Why masseter Botox is so popular in Korea
A soft, tapered "V-line" jaw is a common aesthetic goal in Korea, and a strong masseter muscle can make the lower face look square. Jaw Botox is one of the most requested injectable treatments in Gangnam because it changes the face shape without surgery and with almost no downtime. It is also used to reduce teeth grinding and jaw clenching.
Is your square jaw muscle, fat or bone?
Botox only works on muscle. Before treatment, the doctor will ask you to clench your teeth and feel the muscle. If the width comes mostly from fat, fat-dissolving injections or other contouring may suit you better. If it comes from the jawbone itself, only surgery changes the shape. A good consultation saves you paying for a treatment that cannot work.
Results month by month
- Days 1 to 7: no visible change. Small injection bumps disappear within an hour.
- Weeks 1 to 2: chewing tough food feels more tiring. This is normal and fades as you adapt.
- Weeks 3 to 4: the muscle starts to thin. Friends may not notice yet, but photos show a softer angle.
- Months 2 to 3: peak slimming. The jaw looks narrower from the front and the face more oval.
- Months 4 to 6: the muscle slowly regains strength and bulk.
- Repeat sessions: after two or three treatments, many people need less frequent top-ups.
How many units are used?
Typical doses range from about 20 to 50 Botox-equivalent units per side, depending on muscle size and the product. Very strong muscles may need more. Uneven muscles may get different doses on each side.
Risks and how to avoid them
- Chewing fatigue: common and temporary
- Uneven smile: if toxin spreads to nearby smile muscles; injection placement matters
- Sunken cheeks or sagging: in thinner or older faces, a much smaller muscle can reveal hollowing or jowls
- Paradoxical bulging: rarely, part of the muscle that was not treated bulges when clenching; a small top-up fixes it
Choose a doctor who examines your face from several angles and who adjusts the dose to your age and skin laxity.
Aftercare
- Avoid massaging the jaw for a day
- Skip saunas, intense workouts and alcohol for 24 hours
- Avoid very hard or chewy food in the first weeks if your jaw feels tired
Price
Jaw Botox is usually priced per session (both sides), with large differences between Korean and imported toxins. Ask how many units are included. See our
price guide for current KRW ranges.
Frequently asked questions
Can I get jaw Botox on a short trip?
Yes. It takes minutes and you can fly the next day. Results develop after you go home, so take a front-facing photo before treatment to compare.
Will it affect my smile?
It should not if the injections are placed correctly. Mild asymmetry, if it happens, resolves as the toxin wears off.
Does it help with teeth grinding?
Often yes. Many people report less clenching and fewer morning headaches.
Read more on our
Botox treatment page.
This article is general information and does not replace a consultation with a doctor. Last reviewed: October 2026.
