Thermage FLX®

Thermage FLX® in Seoul at Le.J Plastic Surgery

Medically reviewed by Dr. Kim Ji Sun, M.D., M.S., Ph.D., Board-Certified Otolaryngologist · Le.J Plastic Surgery, Gangnam-gu, Seoul

Thermage FLX® is a non-surgical radiofrequency treatment that heats the deeper layers of the skin to support collagen regeneration over the following months. The clinic describes its Thermage treatment as delivering radiofrequency thermal energy precisely, with the aim of reducing concern about cheek hollowing. At Le.J Plastic Surgery in Gangnam-gu, Seoul, it sits within the clinic's non-surgical lifting programme, one of several energy-based options in the clinic's facial lifting and contouring range, and it is performed personally by Dr. Kim Ji Sun, the clinic's founder and Medical Director and the listed performing doctor for the parent Facial Lifting & Contouring specialty.

What Is Thermage FLX®?

Thermage FLX® uses monopolar radiofrequency energy to heat tissue below the skin's surface, which may support collagen remodeling and improve the appearance of skin laxity, fine lines and wrinkles.

• The energy is monopolar radiofrequency, delivered to planned areas through a handpiece placed against the skin.

• The system incorporates cooling and treatment-delivery features intended to improve delivery and skin-surface comfort.

• The skin is left intact: this is a surface-applied treatment, not an incision or an injection.

• Outcomes may be more subtle than those achieved with surgical lifting.

• The clinic states a treatment duration of approximately 30 to 60 minutes, usually as one treatment session.

The cheek-hollowing point in the clinic's own description deserves unpacking, because it is the specific worry people bring to heat-based tightening in a thinner face. Heat delivered into the wrong plane, or too much of it, can affect the fat that gives a cheek its shape — which is why unwanted fat-volume change appears in the risk list below rather than being left unsaid. What the clinic is claiming is precision in delivery, not immunity from the risk.

Where radiofrequency sits among the alternatives is worth knowing, because this clinic offers several. During a radiofrequency treatment a device is placed against the skin and heats the tissue beneath; most people have one treatment, feel some tightening straight away, the best results appear at around six months as collagen forms, and results can last two to three years with good skincare (AAD). Ultrasound-based lifting reaches deeper layers; laser-based treatments suit other concerns again. None is simply superior — they differ in depth, area and timeline, which is why the device is chosen after assessment rather than requested by name.

The honest framing for the whole category: a surgical lift gives the most dramatic result, and non-invasive tightening trades that for less downtime and lower cost. Expect gradual change rather than a transformation, and be wary of anyone who promises otherwise.

Who Performs Thermage FLX® at Le.J Plastic Surgery

Dr. Kim Ji Sun, M.D., M.S., Ph.D.
Board-certified Otorhinolaryngologist

Thermage FLX® is performed personally by Dr. Kim Ji Sun, the clinic's founder and Medical Director and the listed performing doctor for the parent Facial Lifting & Contouring specialty.

Dr. Kim is a board-certified otolaryngologist who earned an M.D., a Master's degree and a Ph.D. from Dankook University College of Medicine, completed internship and residency at Dankook University Hospital, trained as a Clinical Fellow in the Department of Otorhinolaryngology at Asan Medical Center, and has served as a Guest Professor at Stanford University School of Medicine in the United States. Dr. Kim's most recent relevant academic activity is a 2026 lecture on non-surgical facial rejuvenation and closed rhinoplasty at the 12th meeting of the Korean Academy of Facial Plastic and Reconstructive Surgery, where Dr. Kim is a regular member and serves on the academic, public-relations and international committees.

Le.J Plastic Surgery is a single-doctor clinic, so the surgeon who assesses you is the surgeon who treats you. For a radiofrequency device the judgement that matters is about energy and placement: how much heat goes where, across which areas, in a face with a particular amount of subcutaneous fat. The doctor assesses skin laxity, facial anatomy, treatment goals, medical history, previous aesthetic procedures and relevant medications, then explains the expected benefits, limitations, risks and alternatives before a plan is developed.

Who Is a Good Candidate for Thermage FLX®?

Suitable candidates:

• Adults with mild-to-moderate skin laxity, early facial sagging, fine lines or wrinkles who prefer a non-surgical treatment.

• Patients whose expectations match a gradual, subtle change.

• Patients whose skin condition, facial anatomy and medical history support treatment at examination.

Who should be assessed carefully or postpone:

• People with active skin infection or inflammation in the treatment area.

• Patients who are pregnant.

• Individuals with certain implanted devices or medical conditions that may affect treatment safety.

The doctor assesses individual suitability based on medical history and the device's contraindications. The honest limit on the other side is just as important: Thermage FLX® may not meet the expectations of patients seeking surgical-level lifting. Results also tend to be better in patients at a stable healthy weight who do not smoke and who protect their skin from the sun (AAD).

What to Expect: Procedure, Recovery, and Results Timeline

The consultation assesses skin laxity, facial anatomy, treatment goals, medical history, previous aesthetic procedures and relevant medications, and the expected benefits, limitations, risks and alternatives are explained before any treatment plan is agreed.

The clinic describes the treatment in seven steps: consultation and skin assessment; treatment planning, covering the areas and the settings; cleansing and comfort measures, including the anaesthesia option; energy delivery to the planned areas; cooling and soothing care; aftercare instructions; and follow-up as advised.

Stage	What the clinic states
Treatment duration	Approximately 30–60 minutes
Visits required	Usually 1 treatment session
Anaesthesia	Non-sedation and sedation options
Recovery	Normal daily activities resumed soon after treatment
Stay in Korea	Generally an outpatient procedure; many patients resume daily activities soon after
First visible results	Some patients notice initial tightening after treatment
Final result	Improvements may develop gradually over 2–6 months as collagen remodeling occurs

Sensation during treatment is warmth, brief discomfort, or a deep heating sensation as the energy is delivered. Afterwards, temporary redness, swelling, tenderness, tingling or numbness and occasional bruising are the common effects. Most patients resume normal daily activities soon after the appointment.

Preparation is mostly disclosure. Provide a complete medical history and disclose medications, implanted devices, pregnancy or possible pregnancy, previous fillers or threads, and recent skin treatments. Arrive with clean skin if instructed, and follow the clinic's guidance on skincare products, sun exposure and any anaesthesia-related precautions. Afterwards, follow its instructions for gentle cleansing, moisturisation and sun protection, avoid irritating products or additional procedures until advised that they are appropriate, and contact the clinic if severe or persistent pain, blistering, burns or unusual sensory changes occur.

Results follow the collagen, not the appointment. Some patients may notice initial tightening straight after treatment, while improvements develop gradually over the following weeks or months as collagen remodels — the clinic puts the final result at two to six months. Results and timing vary by individual.

For patients travelling from the United States, this is an outpatient appointment rather than a medical trip: many patients resume daily activities soon after treatment. The clinic has not published a flight-home date for this treatment, which matters less for a no-recovery procedure than it would after surgery, but it is still worth confirming when you book. If something feels wrong after returning home, patients can reach the clinic's English-speaking counselling manager by phone or email.

Combining Thermage FLX® with Other Treatments

Thermage may be considered alongside other aesthetic treatments in selected patients, but suitability, sequencing and timing depend on the procedures involved and individual anatomy. That caveat is doing real work: heat-based treatments and injected materials interact, which is why previous fillers or threads are on the disclosure list rather than treated as irrelevant history.

Within the clinic's own range, the useful contrast is what each technology is aimed at. Ultherapy PRIME® uses microfocused ultrasound to reach deeper layers. Titanium® is laser-based and is positioned around lifting, contouring and brightness together. Endoscopic forehead lifting is surgery, and repositions tissue rather than firming skin. Fat grafting addresses volume rather than either. Beyond the clinic's own range, potential alternatives include other radiofrequency devices, injectable treatments for selected concerns, and thread lifting; the most appropriate option depends on the treatment area, the severity of laxity, anatomy, risk tolerance and the degree of change you want.

Safety, Precision, and Clinic Standards

Le.J Plastic Surgery is a Registered Medical Institution for Attracting Foreign Patients, certified by the Ministry of Health and Welfare in compliance with the Medical Overseas Expansion and Foreign Patients Attraction Act. This is a registration for treating international patients; it is not an accreditation of any treatment in this category.

Non-surgical does not mean risk-free; it means the skin is left intact and the remaining risks are about heat. Possible temporary effects include redness, swelling, tenderness, discomfort and altered sensation. Less common but important risks include burns, blistering, textural irregularities, unwanted fat-volume changes, pigment changes and nerve-related symptoms. Infection is possible but is not typically the primary expected complication of an intact-skin radiofrequency treatment. Persistent pain, blistering, burns or ongoing numbness warrant prompt medical assessment.

What the clinic documents against that is a process: one board-certified otolaryngologist assesses and treats every case, the plan covers both the areas and the settings before energy is delivered, and the system's cooling features are part of how the surface is protected while the deeper layers are heated. The clinic has not published technique details specific to its own protocol, and this page does not supply any in their place.

Two limits, stated rather than glossed. Le.J Plastic Surgery publishes neither case volumes nor complication rates for this procedure, and this page claims neither. Nor has it published a flight-home date for it. Both are fair questions at consultation, alongside the one worth asking about any energy device: which settings are being used on you, and why those.

The Bottom Line

• Thermage FLX® uses monopolar radiofrequency to heat deeper skin layers and support collagen remodeling.

• The clinic states approximately 30 to 60 minutes, usually in one session, with normal activities resumed soon after.

• Initial tightening may be felt straight away; the result develops over two to six months.

• Outcomes are more subtle than surgical lifting, and it may not satisfy someone seeking a surgical-level change.

• Implanted devices, metal under the skin, pregnancy and active skin infection are the exclusions to raise before booking.

• The clinic holds several lifting technologies, so the assessment can honestly end somewhere other than this one.

Frequently Asked Questions

How is radiofrequency different from the clinic's ultrasound and laser options? Radiofrequency heats the tissue beneath a device placed against the skin and is aimed at firmness and fine lines. Microfocused ultrasound reaches deeper layers. The laser option is positioned around lifting, contouring and brightness together. They differ in depth, area and timeline rather than in quality, which is why the device is selected after examination.

Will it hurt, and is anaesthesia used? Patients may experience warmth, brief discomfort, or a deep heating sensation during treatment. The clinic lists both non-sedation and sedation anaesthesia options, and the system's cooling features are part of how surface comfort is managed.

How long does it take, and how many sessions will I need? Approximately 30 to 60 minutes, and usually one treatment session. Whether more would help is a question for the consultation, which assesses laxity, anatomy and what you want the treatment to change.

When will I see the result, and how long does it last? Some patients notice initial tightening after treatment, with improvements developing gradually over the following weeks or months as collagen remodels; the clinic puts the final result at two to six months. Results and timing vary by individual.

Is there downtime, and do I need to stay in Korea? It is generally an outpatient procedure, and many patients resume daily activities soon after treatment. The clinic has not published a flight-home date for this treatment, so confirm your travel plan when you book.

Who should avoid or postpone it? People with active skin infection or inflammation in the treatment area, those who are pregnant, and individuals with certain implanted devices or medical conditions that may affect treatment safety. Tell the clinic about any implanted device or metal under the skin before the appointment, not during it.

What risks should I know about? Temporary redness, swelling, tenderness, discomfort and altered sensation are the common effects. Less common but important risks include burns, blistering, textural irregularities, unwanted fat-volume changes, pigment changes and nerve-related symptoms. Persistent pain, blistering, burns or ongoing numbness warrant prompt medical assessment.

How should I prepare? Provide a complete medical history and disclose medications, implanted devices, pregnancy or possible pregnancy, previous fillers or threads, and recent skin treatments. Arrive with clean skin if instructed, and follow the clinic's guidance on skincare products, sun exposure and any anaesthesia-related precautions.

Book a Consultation at Le.J Plastic Surgery

Thermage FLX® is offered at Le.J Plastic Surgery in Gangnam-gu, Seoul, within a lifting programme that includes surgical and other device-based options. Because the right technology depends on the depth of the problem rather than the name of the device, the useful first step is an assessment. Consultations run Monday to Friday, 10:00–19:00 KST, and Saturday from 10:00 KST. International enquiries are handled by the clinic's counseling manager, Park Somi, and English-language support is available. You can use the clinic's contact page, by phone on +82-2-516-7153, or by email at info@lejplasticsurgery.com.

Disclaimer

This page is for general information only and is not medical advice. Individual results vary and cannot be guaranteed. Suitability for any procedure can only be determined through an in-person medical consultation with a qualified doctor.

Sources & Further Reading

• American Academy of Dermatology — Many ways to firm sagging skin