Myeongdong Botox｜Paradoxical Bulging After Jaw Botox (Causes & Prevention)
Hello,
This is Dr. Hwang Youjoo, Chief Director of Lijin Clinic in Myeongdong.
Botox is one of the most commonly performed procedures in aesthetic clinics.
It is generally safe and provides satisfying results for most patients.
However, like any medical treatment, temporary side effects can occasionally occur.
Serious or permanent complications are extremely rare.
That said, during the 2–3 months while the effects last,
some patients may notice temporary changes or mild discomfort.
What is Paradoxical Bulging?
In rare cases after masseter (jaw) Botox,
a portion of the muscle may appear more prominent,
especially when speaking or chewing.
This phenomenon is known as paradoxical bulging.
Although I have not personally encountered this in my practice,
it is a recognized and possible outcome following jaw Botox.
Today, I’d like to explain in a simple and approachable way
why this happens.
What is Jaw Botox?
Jaw Botox involves injecting botulinum toxin
into the masseter muscle, which is responsible for chewing.
Botulinum toxin works by blocking the release of acetylcholine,
a neurotransmitter that signals muscles to contract.
As a result, muscle activity decreases,
and over time, the enlarged masseter gradually reduces in size.
This leads to a softer, more refined lower facial contour.
Typically:
✔ Results begin to appear after about 2 weeks
✔ Effects last approximately 3–6 months
Why Does Paradoxical Bulging Occur?
This side effect usually appears around one week after treatment.
It is not simply due to muscle reduction.
Rather, it occurs when Botox does not spread evenly within the muscle.
Understanding the Masseter Muscle Structure
To understand this, we need to look at the anatomy of the masseter.
The masseter consists of:
✔ A superficial layer
✔ A deep layer
Between these layers lies a structure called the
Deep Inferior Tendon (DIT).
This structure plays a key role in this phenomenon.
The Role of the DIT
In most cases, Botox is injected into the deep layer,
and it naturally diffuses into surrounding areas.
However, depending on individual anatomy,
the DIT can act as a barrier,
preventing the toxin from spreading evenly to the superficial layer.
As a result:
✔ The deep layer becomes weaker
✔ The superficial layer remains relatively active
To compensate, the superficial layer contracts more strongly,
leading to a visible bulge when chewing.
A Simple Way to Think About It
Imagine two people carrying something heavy together.
If one suddenly stops using their strength,
the other has to compensate and work harder.
Similarly,
when the deep layer weakens,
the superficial layer takes over —
causing that noticeable bulging.
Individual Anatomy Matters
The structure of the masseter varies from person to person.
In some cases,
the DIT partially surrounds the superficial layer,
making it more likely that Botox does not spread evenly.
This anatomical variation increases the likelihood of
paradoxical bulging.
In addition,
if injections are placed too deep or too closely together,
the superficial layer may not be sufficiently treated.
How to Prevent It
Prevention starts with proper assessment before the procedure.
✔ Check for any previous history of this side effect
✔ Evaluate muscle thickness and movement carefully
✔ Consider the layered structure of the muscle
✔ Distribute injections evenly across different depths
A customized approach is key.
What If It Happens?
If you notice this bulging after treatment,
it can be surprising at first.
However, in most cases,
it improves naturally over time.
As Botox gradually takes effect and diffuses,
the imbalance often resolves on its own.
For quicker improvement,
a simple solution is available:
👉 A small additional injection into the superficial layer
can effectively correct the imbalance.
It’s Not About Quantity — It’s About Precision
Jaw Botox may seem simple,
but in reality, it requires careful evaluation.
✔ Muscle thickness
✔ Movement patterns
✔ Facial balance
✔ Overall contour
All of these factors must be considered.
Ultimately,
the result depends not just on how much Botox is used,
but where and how it is placed.
When treatment is tailored to each individual,
more natural and balanced results can be achieved.
Changes after Botox are often not random side effects,
but rather the result of underlying muscle structure and function.
While they may feel unexpected,
most can be understood, managed, and improved
with the right approach.
I hope this explanation was helpful
for those who may have been concerned.
Thank you for reading.
Dr. Hwang Youjoo
Chief Director, Lijin Clinic, Myeongdong
This is Dr. Hwang Youjoo, Chief Director of Lijin Clinic in Myeongdong.
Botox is one of the most commonly performed procedures in aesthetic clinics.
It is generally safe and provides satisfying results for most patients.
However, like any medical treatment, temporary side effects can occasionally occur.
Serious or permanent complications are extremely rare.
That said, during the 2–3 months while the effects last,
some patients may notice temporary changes or mild discomfort.
What is Paradoxical Bulging?
In rare cases after masseter (jaw) Botox,
a portion of the muscle may appear more prominent,
especially when speaking or chewing.
This phenomenon is known as paradoxical bulging.
Although I have not personally encountered this in my practice,
it is a recognized and possible outcome following jaw Botox.
Today, I’d like to explain in a simple and approachable way
why this happens.
What is Jaw Botox?
Jaw Botox involves injecting botulinum toxin
into the masseter muscle, which is responsible for chewing.
Botulinum toxin works by blocking the release of acetylcholine,
a neurotransmitter that signals muscles to contract.
As a result, muscle activity decreases,
and over time, the enlarged masseter gradually reduces in size.
This leads to a softer, more refined lower facial contour.
Typically:
✔ Results begin to appear after about 2 weeks
✔ Effects last approximately 3–6 months
Why Does Paradoxical Bulging Occur?
This side effect usually appears around one week after treatment.
It is not simply due to muscle reduction.
Rather, it occurs when Botox does not spread evenly within the muscle.
Understanding the Masseter Muscle Structure
To understand this, we need to look at the anatomy of the masseter.
The masseter consists of:
✔ A superficial layer
✔ A deep layer
Between these layers lies a structure called the
Deep Inferior Tendon (DIT).
This structure plays a key role in this phenomenon.
The Role of the DIT
In most cases, Botox is injected into the deep layer,
and it naturally diffuses into surrounding areas.
However, depending on individual anatomy,
the DIT can act as a barrier,
preventing the toxin from spreading evenly to the superficial layer.
As a result:
✔ The deep layer becomes weaker
✔ The superficial layer remains relatively active
To compensate, the superficial layer contracts more strongly,
leading to a visible bulge when chewing.
A Simple Way to Think About It
Imagine two people carrying something heavy together.
If one suddenly stops using their strength,
the other has to compensate and work harder.
Similarly,
when the deep layer weakens,
the superficial layer takes over —
causing that noticeable bulging.
Individual Anatomy Matters
The structure of the masseter varies from person to person.
In some cases,
the DIT partially surrounds the superficial layer,
making it more likely that Botox does not spread evenly.
This anatomical variation increases the likelihood of
paradoxical bulging.
In addition,
if injections are placed too deep or too closely together,
the superficial layer may not be sufficiently treated.
How to Prevent It
Prevention starts with proper assessment before the procedure.
✔ Check for any previous history of this side effect
✔ Evaluate muscle thickness and movement carefully
✔ Consider the layered structure of the muscle
✔ Distribute injections evenly across different depths
A customized approach is key.
What If It Happens?
If you notice this bulging after treatment,
it can be surprising at first.
However, in most cases,
it improves naturally over time.
As Botox gradually takes effect and diffuses,
the imbalance often resolves on its own.
For quicker improvement,
a simple solution is available:
👉 A small additional injection into the superficial layer
can effectively correct the imbalance.
It’s Not About Quantity — It’s About Precision
Jaw Botox may seem simple,
but in reality, it requires careful evaluation.
✔ Muscle thickness
✔ Movement patterns
✔ Facial balance
✔ Overall contour
All of these factors must be considered.
Ultimately,
the result depends not just on how much Botox is used,
but where and how it is placed.
When treatment is tailored to each individual,
more natural and balanced results can be achieved.
Changes after Botox are often not random side effects,
but rather the result of underlying muscle structure and function.
While they may feel unexpected,
most can be understood, managed, and improved
with the right approach.
I hope this explanation was helpful
for those who may have been concerned.
Thank you for reading.
Dr. Hwang Youjoo
Chief Director, Lijin Clinic, Myeongdong
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