Chin Fullness: Salivary Gland, Not Fat?

That fullness under your chin —

it might not be fat at all.

Let me get straight to the point.

If the puffiness under your chin just won't budge no matter how much weight you lose,

there's a good chance it's not fat —

it's your submandibular gland.

Let me walk you through exactly why that happens.

Submandibular Gland Botox

Is Not the Same as masseter botox

Submandibular gland Botox involves injecting toxin directly into the salivary glands (submandibular glands) located on either side beneath your chin.

The goal is to reduce the actual volume of the gland itself — reshaping the jawline from within.

It's an entirely different procedure from masseter botox, which targets muscle. The location, depth, and dosage are all completely different.

Why Doesn't the Area Under Your Chin Slim Down Even After Weight Loss?

"If you're wondering whether the fullness under your chin is fat or a salivary gland,

try this: relax your jaw completely and gently press on both sides beneath your chin.

If you feel something firm and rounded — almost like a marble —

that's your submandibular gland."

— Dr. Wi Young-jin (Beautystone Clinic, Hongdae)

The fullness under the chin is typically a combination of fat, sagging skin, and salivary glands.

Fat responds to diet and weight loss.

Loose skin can be addressed with Lifting procedures.

But salivary glands? Neither of those approaches will reduce them.

Salivary glands are tissue that can enlarge with increased activity — like eating quickly or frequently consuming acidic foods.

They enlarge through a completely different mechanism than fat accumulation — diet has no effect on them.

Typically, a combined dose of around 20–40 units is injected across both sides. Many patients notice a noticeably sharper jawline after about 2 sessions spaced 3 months apart.

It's worth noting that pushing the dosage too high in one session can lead to significant dry mouth — something to keep in mind.

Which Type Describes Your Chin Profile?

Check the table below to find the approach that fits your concern.

Type	Characteristics	Recommended Approach
Enlarged Submandibular Gland	Firm, symmetrical masses felt on both sides beneath the chin	Submandibular gland Botox (20–40U)
Fat-Dominant	Soft and pinchable; reduces with weight loss	Contouring injection or liposuction
Sagging-Dominant	Disappears when head is tilted up; more prominent when looking down	Lifting procedures such as Shrink or Ultherapy
Combined	A mix of all three (the most common presentation)	Botox combined with Lifting

I generally don't recommend this procedure for patients who already experience chronic dry mouth — but for most people, any temporary dryness resolves on its own fairly quickly.

The Three Questions I Hear Most Often in the Clinic

Q1. Will I see results as quickly as with masseter botox?

With masseter botox, visible volume reduction typically appears within 4–6 weeks.

The submandibular gland, however, is a secretory gland — most patients don't notice a meaningful change until around 6–8 weeks in.

Give it at least two months before drawing any conclusions. Patience is key here.

Q2. If it doesn't seem to be working, does that mean I've built up resistance? Should I increase the dose?

Evaluating results before the 6-week mark is simply too early.

If resistance is genuinely suspected, the right approach is to switch to a different formulation or allow a rest period —

arbitrarily increasing the dosage only raises the risk of unwanted side effects.

Q3. Will it make swallowing difficult or cause dry mouth?

There are multiple pairs of salivary glands in the mouth, so reducing only the submandibular glands won't cause complete dryness or difficulty swallowing.

That said, staying within the appropriate dosage range — administered by an experienced injector — is essential.

If you take one thing away from today's post —

stand in front of a mirror, relax your jaw completely,

and gently press beneath your chin.

If something firm and rounded presses back,

that's not fat — that's a salivary gland.

In my next post, I'll be sharing a real case study:

Submandibular Gland Botox — What Changes at the 6-Week Mark.

This is Dr. Wi Young-jin. See you next time.

Further Reading

• Can Cheekbone Botox Cause Mouth Drooping? [Why Needle Changes Matter]

• Just Got Botox? Don't Expect Instant Results — Here's Why It Varies by Area

• Always Searching for the Cheapest masseter botox? Here's Why That Number Can Be Misleading

Frequently Asked Questions

Q1. How do I know if the fullness under my chin is fat or a salivary gland?

Try relaxing your jaw completely and gently pressing on both sides beneath your chin. If you feel something firm and rounded — almost like a marble — that's likely your submandibular gland rather than fat.

Q2. Is submandibular gland Botox the same as masseter (jaw) Botox?

No — they're entirely different procedures. Submandibular gland Botox targets the salivary glands beneath the chin to reduce their volume, while masseter Botox targets the jaw muscle. The location, depth, and dosage all differ.

Q3. Why doesn't the area under my chin slim down even after losing weight?

Fullness under the chin is often a mix of fat, loose skin, and salivary glands. Diet and weight loss only affect the fat component — enlarged salivary glands don't respond to weight loss at all, since they enlarge through a different mechanism.

Q4. How many sessions are needed, and are there side effects?

A combined dose of around 20–40 units is typically injected across both sides, with many patients noticing a sharper jawline after about 2 sessions spaced 3 months apart. Pushing the dosage too high in one session can lead to noticeable dry mouth, so dosing should be paced carefully.