InMode FX Side Effects: Why Cheek Hollowing Beneath the Cheekbones Is the Most Serious Risk

InMode FX Side Effects: Why Cheek Hollowing Beneath the Cheekbones Is the Most Serious Risk

Before you read, let's clear something up

Q. Doesn't InMode FX deliver similar results regardless of the treatment area?

A. Not at all.

The submental area has a thicker fat layer, while the area beneath the cheekbones is much thinner — apply the same energy output to both, and you'll get completely opposite results.

Q. I feel a burning sensation and have Swelling after the procedure — are these side effects?

A. Those are generally normal reactions. The side effect you really need to watch out for is asymmetric cheek hollowing.

First, What Makes InMode FX Different from Other Radiofrequency (RF) Devices?

InMode FX delivers bipolar Radiofrequency (RF) energy

to the superficial skin layers

to directly disrupt fat cell membranes.

Unlike monopolar Radiofrequency (RF) devices such as Thermage or Oligio X,

FX uses a narrowly spaced dual-electrode configuration

to concentrate energy precisely at the boundary between the Dermis and superficial subcutaneous fat.

This means the procedure leans more toward

"modest fat reduction with simultaneous skin tightening" rather than pure Lifting.

Why Does Cheek Hollowing Occur Beneath the Cheekbones?

The way InMode FX works is actually similar to heating food in a microwave.

Thicker food heats through evenly,

but thin portions burn quickly.

FX behaves the same way.

In areas with a thicker fat layer — like the submental region and Double Chin — slightly higher energy output is generally safe,

but in areas like beneath the cheekbones where the fat layer is only 2–5mm thick,

applying the same output can cause excessive disruption of fat cell membranes.

The result is precisely that cheek hollowing effect.

This is something many patients misunderstand —

InMode FX doesn't "melt" fat.

It uses bipolar Radiofrequency (RF) to directly destroy fat cell membranes.

Once those membranes are disrupted, macrophages spend several months

clearing away the debris,

and if the cleared volume is too large,

the area visibly sinks inward.

That's why when I treat the 2–5mm zone beneath the cheekbones,

I reduce the energy output by one or two levels compared to the submental area.

Skip that subtle adjustment,

and two to three months later patients look in the mirror and ask,

"Why does it look sunken right below my cheekbones?"

I see this scenario often enough that it's worth documenting here.

Last month, a 44-year-old patient came in

after receiving one FX session at another clinic,

and by week two she was concerned that her face looked even more sagging than before.

My initial thought was an energy output issue,

but on examination I could see this was actually the phase where post-procedure Swelling was subsiding,

temporarily making the sagging appear more pronounced.

She waited about six weeks without any additional procedures,

and her next session was performed with reduced output specifically in the sub-cheekbone area —

by the three-month mark, she was the first to say she was satisfied with the results.

Area-Specific Output Matters — And Here Are the Limitations of This Procedure

That said, this isn't a procedure that works perfectly for everyone.

There's one important point I need to make clear:

InMode FX alone cannot address sagging at the depth of the SMAS Layer.

FX targets the Dermis-to-superficial subcutaneous fat boundary,

so patients with laxity at the fascial level

will need to combine it with a HIFU-based procedure (such as Ultherapy) or a Thread lift

to achieve meaningful results.

That said, for those concerned about Fine Lines, Pores, and mild skin laxity,

it remains a strong option.

A quick visual overview makes this much clearer.

Even from a table alone, the pattern becomes obvious —

reducing side effects requires different approaches for different areas,

even with the same device and the same number of sessions.

One 55-year-old patient told me in her first week

that she was nervous because it looked like the area beneath her cheekbones had sunk in.

At that point, the surrounding tissue was still swollen,

which made the sub-cheekbone area appear relatively more hollowed,

but around the six-week mark, as the Swelling resolved,

everything settled into the contour we had originally intended.

"Waiting is the hardest part," she told me herself.

The 3 Questions I Hear Most Often About InMode FX Side Effects

Q1. The day after my procedure, my skin is red and burning — is this the start of a side effect?

A. This one is actually a bit nuanced,

but in most cases this falls within the normal reaction range, not a side effect.

When bipolar Radiofrequency (RF) leaves residual heat in the Dermis,

Erythema and a burning sensation lasting approximately 24–72 hours is typical,

and it generally resolves with ice packs and Calming care.

However, if one side remains significantly more red than the other beyond three days,

or if blisters or Scabs develop, please come in for a consultation.

And here's another question that comes up constantly.

Q2. If cheek hollowing develops after I've already paid for the procedure, can it be reversed?

A. To be honest with you,

fat cells that have already been destroyed cannot be restored.

Instead, we approach it by restoring volume to the affected area

using Filler or a Collagen stimulator like Sculptra.

This is precisely why reducing the energy output beneath the cheekbones from the start is far more cost-effective.

Results typically last around one year,

and patients who receive two to three sessions at six-month intervals tend to report the highest satisfaction.

Q3. It looked great right after the procedure, but two weeks later my face looks more sagging. Did something go wrong?

A. When I see patients at this stage in the clinic,

a significant number of them are genuinely worried.

Right after the procedure, temporary Swelling adds volume that masks sagging —

then, as the puffiness subsides in weeks one and two,

there's a brief window where the face can appear more sagging than before.

It's understandably confusing,

but the real results only begin to emerge from weeks four to eight,

as Collagen remodeling takes place.

Until that point, it's best to hold off on making any final judgments.

If there's one thing to take away from today — the safety of InMode FX doesn't come from the energy number on the display. It comes from a clinician's ability to read the fat layer thickness of each individual area.


In my next post, I'll walk through how I structure a recovery plan for patients who already have existing cheek hollowing — including which combination of Filler, Sculptra, and regenerative procedures best fits each case. This has been Dr. Wi Young-jin.