XERF vs Thermage FLX vs Ultherapy: Differences, Pain & Downtime (2026)

Quick answer: XERF, Thermage FLX, and Ultherapy all tighten and lift the skin, but they work at different depths. Thermage FLX is single-frequency RF that works mainly in the dermis. Ultherapy is focused ultrasound (HIFU) that targets the SMAS layer. XERF is dual-frequency RF (6.78MHz + 2MHz) that reaches from the dermis down to the SMAS, with little pain and virtually no downtime.

Key takeaways

• Thermage FLX: known for collagen tightening and smoother skin texture; works mainly in the dermis.
• Ultherapy: the most direct lift for sagging, but more painful, with 1–2 weeks of swelling and nerve-sensitive areas it can't treat.
• XERF: tightening and lifting in one treatment, reaching the SMAS with RF; usually no numbing cream and virtually no downtime.
• Jowls and marionette lines: treatable with XERF and Thermage FLX, but limited with Ultherapy.
• Combining: XERF and Ultherapy work differently and can be combined after a doctor's assessment.

If you're planning an aesthetic treatment in Seoul, these three come up more than any others. Below, the dermatologists at Seye Clinic in Gangnam explain how they work, how they feel, and who each one suits.

What is the difference between RF and ultrasound (HIFU) lifting?

RF heats a broad volume of tissue to tighten the skin. Ultrasound focuses heat into tiny points at set depths, making the tissue contract and lift.

• RF (radiofrequency): Volumetric heating that stimulates collagen in the dermis. The energy is gentle and even, with almost no downtime. Traditional RF stays mostly in the dermis, so it can only do so much for skin that is already sagging.
• Ultrasound lifting (HIFU): Focused energy creates thermal coagulation points that make tissue contract strongly. The lift is direct and noticeable, but it hurts more, swelling can last 1–2 weeks, and nerve-sensitive areas such as the jowls and marionette lines are restricted.

XERF was designed to fill the gap between the two.

What is XERF?

XERF (eXperience Exponential RF) is a monopolar RF device from Korean medical device company Cynosure Lutronic that delivers two frequencies, 6.78MHz and 2MHz, at the same time.

Traditional RF uses a single 6.78MHz frequency that works mainly in the dermis. According to the manufacturer, XERF is the first device to add a lower 2MHz frequency, which carries heat past the dermis into the subcutaneous fat and the SMAS layer. That is what allows it to tighten and lift at once.

Related clinical study: Efficacy of dual-frequency noninvasive monopolar radiofrequency in skin tightening: Histological evidence

XERF vs Thermage FLX vs Ultherapy: side-by-side comparison

Individual results vary. Your doctor will recommend a treatment after assessing your skin.

How is XERF different from Thermage FLX?

Both are monopolar RF, but XERF reaches deeper and is usually more comfortable. Thermage FLX works mainly in the dermis, while XERF's second frequency reaches the SMAS layer, so it can lift sagging tissue as well as tighten.

Treatment depth

Thermage FLX is one of the best-known RF treatments, with a solid clinical track record for collagen tightening. Because its energy stays mostly in the dermis, many people notice better skin quality and a slightly sharper jawline, but less change in sagging. XERF keeps the comfort and zero downtime of RF while adding a deeper lifting effect.

Treatment tip

Thermage FLX uses a solid tip that can cause an “edge effect,” spreading energy unevenly. XERF's web-patterned tip is designed to remove the edge effect so energy covers the treatment area evenly. Its 6cm² facial tip, which the manufacturer describes as the largest of its kind, covers about 50% more area than comparable devices, so sessions are shorter.

Comfort

Thermage FLX is often described as sharp and prickly, and most patients need numbing cream. XERF's patented Wave Fit Pulse™ technology delivers energy across 12 graded steps instead of 5 fixed levels, and a three-stage ICD cooling spray protects the skin surface. It feels warm rather than sharp and typically doesn't require numbing cream.

How is XERF different from Ultherapy?

They reach similar depths in different ways. Ultherapy focuses ultrasound into hot spots that make the SMAS contract, while XERF heats tissue evenly with RF and strengthens the retaining ligaments.

Why XERF can treat the jowls and marionette lines

Ultherapy's concentrated heat can't be used near nerve-dense areas, including the jowls and around the marionette lines. Left untreated, lines in those areas can deepen over time. Because XERF doesn't rely on focused hot spots, these areas can be treated safely, covering the spots Ultherapy can't reach.

Pain and downtime

If you're fitting treatment into a short trip and can't take time off to recover, XERF's minimal downtime is a real practical advantage.

Can XERF and Ultherapy be combined?

Depending on your skin, yes. Ultherapy contracts the SMAS while XERF strengthens the supporting ligaments, so together they can give a more complete lift than either alone. Your doctor will decide the order and timing.

How does XERF compare with Oligio?

Both are comfortable RF treatments. Oligio heats the dermis evenly and focuses on tightening and maintenance, so it suits preventive care when early signs of aging appear. XERF offers similar comfort, but its dual frequency reaches the SMAS layer for both tightening and lifting, so it suits visible laxity, sagging, or a softening jawline.

Which treatment is right for me?

• Choose Thermage FLX if you mainly want collagen tightening and better skin texture.
• Choose Ultherapy if you want the most direct lift and can manage some discomfort and 1–2 weeks of swelling.
• Choose XERF if you want tightening and lifting with little pain and no downtime, or your main concern is sagging jowls or marionette lines.
• Consider XERF + Ultherapy if you want a fuller lift and your doctor confirms it suits your skin.

How often should you get XERF, Thermage FLX, or Ultherapy?

XERF is usually done in 300- or 600-shot sessions. Your doctor will set the number of shots based on your face and goals.

Why get XERF at Seye Clinic in Seoul?

Performed by dermatologists

Seye Clinic's doctors trained at Korean institutions including Seoul National University, Yonsei University, and Asan Medical Center. XERF is performed by a dermatologist, never handed off to an assistant, and depth and energy are adjusted to your skin during treatment.

Genuine products, full doses

Every treatment uses authentic manufacturer consumables at the full dose the manufacturer specifies, with no reduced shots or lowered energy.

English-language support

From your assessment and doctor consultation to aftercare instructions, English-language support is available throughout your visit.

Easy to reach in Gangnam

A 5-minute walk from Sinnonhyeon Station Exit 7 or Gangnam Station Exit 10.

XERF FAQ

Does XERF hurt?

Pain is typically around 5 out of 10 and feels like warmth rather than a sharp sting. Numbing cream usually isn't needed.

Is there downtime after XERF?

There is virtually no downtime. You can go about your day right after treatment; just keep your skin moisturized and protected from the sun.

Can I fly home the same day after XERF?

Yes. Because there's virtually no downtime, XERF doesn't usually affect travel plans.

How long do XERF results last?

Clinical data shows the tightening and lifting from a single session can last up to 12 months. Daily sunscreen and moisturizing help results last longer.

How many shots of XERF do I need?

XERF is usually done in 300- or 600-shot sessions. Your doctor decides the number after assessing your face.

Who is a good candidate for XERF?

XERF suits people with visible laxity, sagging, or a softening jawline who want lifting without much pain or downtime, including those concerned about the jowls and marionette lines.

Can I get XERF and Thermage FLX on the same day?

We recommend spacing them out. Tell your doctor about any recent treatments so they can plan the best timing.

Can XERF and Ultherapy be done on the same day?

In some cases, yes. Your doctor will assess your skin and plan the right order and timing.

I've already had Thermage FLX. Do I still need XERF?

They work on different layers. If you liked the tightening from Thermage FLX but still notice sagging, XERF adds the deeper lift Thermage FLX doesn't reach.

The bottom line

Thermage FLX is for collagen tightening, Ultherapy is for a strong, direct lift, and XERF combines tightening and lifting with comfort and no downtime, including areas ultrasound can't treat. At Seye Clinic, our dermatologists recommend the treatment that fits your face, not the most expensive one.

Book a consultation at Seye Clinic

Clinic: Seye Clinic, Gangnam, Seoul

Address: 10F, Aprosquare Building, Seocho-gu, Seoul

Getting here: 5-minute walk from Sinnonhyeon Station Exit 7 or Gangnam Station Exit 10

Book on WhatsApp: +82-10-3110-9806

Individual results vary. Treatment is decided after a consultation with a doctor. This content was written in accordance with the Korean Medical Service Act and Ministry of Health and Welfare regulations on medical advertising.