Jaw Botox vs. Fat Dissolving: Muscle or Fat?

If your face looks wide because of soft fat on the cheeks and under the chin, fat dissolving injections are the ones to look at first. If the width comes from the chewing muscle at the corner of your jaw, jaw Botox is. A "contour injection" isn't one specific drug. It's a name clinics use for their own mixes, so what's inside varies from place to place.

In this article, we'll cover a quick way to tell fat from muscle, what deoxycholic acid is actually approved for, when jawline Botox starts to show, which side effects pass and which need a doctor, and how the three injections compare side by side.

Quick summary

• Fat points you toward fat dissolving or contour injections first, while a bulky chewing muscle points you toward jaw Botox.
• Self-check: if the corner of your jaw turns hard and bulges when you clench, muscle is the bigger factor.
• In a study of 90 people, jaw Botox thinned the muscle gradually over 12 weeks.
• Fat injections under the chin are usually given in 2 sessions, 6 to 8 weeks apart.

Is Your Wide Jaw From Fat or the Masseter Muscle?

Bite down hard on your back teeth, then relax. If the area just below your ear, at the corner of the jaw, turns firm and rises as you clench, the masseter (the chewing muscle on each side of the jaw) is probably large. If the shape barely changes when you clench and you can pinch soft tissue along your cheeks and jawline, fat is the more likely cause.

At the consultation, I start by looking at the outline of your face. Then I feel along the jaw and ask you to clench, to see whether the muscle pushes outward. When muscle is the main issue, Botox is the treatment to think about. When the jawline itself has started to sag, a lifting treatment such as Ultherapy comes into the conversation instead.

Neither finding settles the plan on its own. The exam also checks whether the jaw muscles on your left and right are different sizes, because an uneven pair changes where and how much gets injected.

Is Deoxycholic Acid the Same as a Contour Injection?

Not necessarily, so ask what's in the syringe before you agree to one. A contour injection and a "fat dissolving injection" can both mean different mixtures and doses at different clinics, and the name alone won't tell you which ingredient you're getting.

Among fat-reducing injectables, the ingredient that has gone through FDA approval is deoxycholic acid (sold in the US as Kybella). It resembles the bile acid your body uses to break down fat from food, and it destroys fat cells where it's injected.

In a trial of 506 adults with fat under the chin, 256 received deoxycholic acid and 250 received a placebo. Twelve weeks after the last session, 70.0% of the treated group had improved by at least one grade, compared with 18.6% on placebo. By the doctors' ratings, 55% had improved after 2 sessions and 75% after 4. Results differ from person to person.

Don't expect a big change after one visit. Under-chin injections are usually given in 2 sessions spaced 6 to 8 weeks apart, and the full effect shows about 3 to 4 months after the last one*.

*Based on American Academy of Dermatology patient guidance.

If you searched for fat dissolving injections for the cheeks, here's the catch. The approval covers fat under the chin. For fat elsewhere on the face, including the cheeks, safety and effectiveness haven't been established, and it isn't recommended*.

*Based on the FDA prescribing information for Kybella.

So if a contour injection is offered for your cheeks, ask three things: the name of the ingredient, how much goes in per session, and how many sessions are planned and how far apart.

When Does Jawline Botox Start to Show?

Jawline Botox shows up gradually, over weeks, as the masseter gets thinner. In a study of 90 people with enlarged masseters, a different botulinum toxin product (prabotulinumtoxinA) was tested at four doses against a placebo and followed for 16 weeks. Muscle thickness and volume went down slowly over the first 12 weeks.

Higher doses shrank the muscle more, but that came with a trade-off. The lowest dose, 24 units, wasn't enough, and people in the 96-unit group reported discomfort when moving the jaw. How much your jaw changes depends on your muscle.

That's why judging the result in the mirror at 2 or 3 weeks is too early. Take front and side photos before treatment. At week 12, retake them in the same light and at the same angle. If one side shrinks more than the other, those photos become the reference point for your next visit.

Fat Dissolving and Jaw Botox Side Effects: What Passes and What Needs a Doctor

Swelling and bruising are common after fat injections under the chin. When the swelling is heavy, it can last up to 2 weeks, and the area may feel firm or lumpy for a while*. If that swelling keeps getting worse instead of settling, contact your provider.

*Based on American Academy of Dermatology patient guidance.

It's better to postpone either injection if any of these apply to you:

• An infection or inflammation where the injection would go
• You bleed easily, or you take antiplatelet or blood-thinning medication
• You've had trouble swallowing in the past (fat injections)
• You've had an allergic reaction to botulinum toxin (jaw Botox)

Don't wait to see if it settles if you notice any of these. See a doctor right away:

• The injected skin turns white, or develops a dark, net-like discoloration
• Blisters, or skin that breaks down and weeps
• One corner of your mouth doesn't lift properly when you smile
• Trouble swallowing, breathing, or speaking (after jaw Botox, this can appear anywhere from hours to weeks later)

In the deoxycholic acid trial, a drooping corner of the mouth from nerve irritation happened in 4.3% of treated people, and most cases were mild and passed. The whitening skin change comes from case reports where the injection went into a blood vessel. Breathing, swallowing, and speaking problems after Botox are very rare*. A message to the clinic doesn't replace an in-person exam.

*Based on American Academy of Dermatology guidance on botulinum toxin.

Contour Injection vs. Fat Dissolving vs. Jaw Botox: How Do They Compare?

The three injections target different tissue at different depths, so their results show up at different speeds. A contour injection only fits into one of these columns once you know what's in it.

If you have both fat and muscle, compare the last two columns and start with whichever one is contributing more.

Jaw Botox or Fat Dissolving Within Your Travel Itinerary in Korea

Unless you had sedation that day, there's no need to postpone your flight home because of jaw Botox or a fat dissolving injection.

It helps to know what one visit can do, too. Some treatments, like fillers, change your shape the same day. Most others, these injections included, don't transform your face in one go. They bring you gradually closer to how you used to look, and with jaw Botox, the change keeps building for weeks after you've left. If more than one session is planned, a single visit doesn't replace the rest of the course.

Since the week-12 photo check usually falls after your trip, take your before photos while you're in Seoul and repeat them at home with the same setup. Once you're back, you can send those photos through the consultation button on this page with any questions about your progress. If a reaction looks serious, get seen by a local doctor first rather than waiting for a reply.

The Bottom Line on Fat Dissolving vs. Jaw Botox

Before you decide, bring one question to your consultation: how much does my jaw muscle bulge when I clench? Then ask which ingredient is in any injection being suggested to you. Those two answers make the three options far easier to compare. Like any procedure, each comes with trade-offs, and the right fit depends on your face and your goals.

Beautystone is a clinic in Seoul's Hapjeong area. When you reach out, include a front photo and a side photo, the names of any injections you've had before, and roughly when you had them.

Sources

• Sessions, timing of results and swelling after fat injections under the chin, American Academy of Dermatology
• Deoxycholic acid vs. placebo for fat under the chin, phase 3 trial of 506 adults, Dermatol Surg, 2016
• How long results lasted, up to 3 years after fat injections under the chin, Aesthet Surg J, 2021
• Serious side effects such as skin damage and nerve injury after deoxycholic acid injections, Aesthet Surg J Open Forum, 2024
• Four doses of botulinum toxin for enlarged masseters, 90 people over 16 weeks, Dermatol Surg, 2021
• Botox for masseter prominence, 187 people over 1 year vs. placebo, J Am Acad Dermatol, 2025
• How bite force drops and returns after masseter botulinum toxin, 1-year study, J Oral Rehabil, 2023
• Very rare breathing, swallowing and speaking problems after Botox, American Academy of Dermatology

Frequently Asked Questions

Q. Can I get jaw Botox and fat dissolving injections together?

A. Jaw Botox and fat dissolving injections target different tissue, muscle and fat, so if you have both concerns, both can come up at one consultation. We didn't find a set standard on whether to do them the same day or which to do first with a gap in between. That's decided at the visit, based on which one is bigger and whether you've had any injections recently.

Q. How long does masseter Botox last?

A. There's no single re-treatment interval for masseter Botox, and the studies differ. In a 90-person study, the authors suggested injecting again after 12 weeks, while a 187-person study of Botox allowed re-treatment at 6 months if needed. When you come back depends on how much the muscle has recovered.

Q. Does masseter Botox make it hard to chew?

A. Masseter Botox can weaken your bite for a while. In a study of 20 people who got Xeomin, 25 units in each masseter (50 units total), and were followed for a year, maximum bite force was lower at 3 months. By 6 months, it was no longer clearly different from where they started. If tough foods feel hard to chew, mention it at your next visit.

Q. Can masseter Botox affect my smile?

A. Masseter Botox can occasionally affect your smile, and in one study it showed up at the highest dose. Among 187 people treated with Botox in the masseter and followed for a year, 4 who received 96 units had changes in how their smile looked. If one corner of your mouth won't lift properly, see a doctor right away.

Q. Does fat come back after fat dissolving injections under the chin?

A. Improvement under the chin held for up to 3 years in most people who were followed. Among 224 people who had improved 12 weeks after their last session, 86.4% of the treated group still showed it at 1 year, compared with 56.8% in the placebo group. No new treatment-related side effects were reported over the 3 years.

Q. How many fat dissolving sessions do I need?

A. For deoxycholic acid under the chin, the US approval allows up to 6 sessions, given at least one month apart. In one clinic's records of 1,269 people treated with a phosphatidylcholine and deoxycholic acid mix, the average was 4 sessions, 4 weeks apart, though that was a look back at records with no comparison group. Your number of sessions is set at the visit, based on how thick the fat is.

Q. Do contour injections hurt?

A. We didn't find a study that measured pain for contour injections specifically. In the approval trials of deoxycholic acid under the chin, 70% of treated people had pain at the injection site. The numbing method, such as numbing cream, is decided at the visit based on the area and how sensitive you are.

Q. Can fat dissolving injections get rid of a double chin?

A. If a double chin comes from fat under the chin, it falls within the US approval for deoxycholic acid. An enlarged thyroid or swollen lymph nodes in the neck can also make the area look full, so those need to be ruled out first. People with very loose skin were left out of the approval trials, so if sagging is the bigger issue, lifting comes into the conversation.