Is 40 kJ of Onda Coolwaves Enough? Reading the Numbers Before Your Korea Visit

I'm Dr. Hyunji Kim, director and lead physician at Delphic Clinic in Gangnam, Seoul. My background is Korea University Medical Center, and I'm a member of the Korean Academy of Aesthetic Surgery & Laser Medicine, the Korean Society for Laser Dermatology & Hair, the Korean Society for Obesity & Aesthetic Treatment and the Korean Filler Society. Lifting, laser and anti-aging treatment is most of my working day.

In consultation, someone in their fifties, or a grown son or daughter sitting beside a parent, holds up a phone with a Korean clinic menu and points at "40 kJ" and "60 kJ". They've searched onda coolwaves korea, they know it's a microwave device, and what they really want to know is whether the bigger number buys a bigger result.

Not by itself. The kJ figure is the total energy the device delivers in a session. Whether 40 is plenty or 60 is too much depends on the amount of fat in the area, how large the area is and how thin the skin over it is.

• Onda is DEKA's microwave device, and Coolwaves is the maker's name for the 2.45 GHz technology inside it.
• kJ is a dose of energy, not a promise of lift. The same number can suit one face and be wrong for another.
• Faces with very little fat, or sagging that really needs surgery, are poor matches.
• The published evidence is real but small, and almost all of it is on the body.
• At Delphic, Onda, Ulthera, Thermage FLX and Titanium are all available, so the device can be chosen after the exam, and a doctor performs the treatment.

What does "Onda Coolwaves" actually mean?

Onda is the device; Coolwaves is the technology inside it. DEKA, the Italian manufacturer, lists the source as microwaves at 2.45 GHz and describes them as selectively targeting fat cells in the layer under the skin, while also shrinking collagen fibers in the dermis (DEKA product page). In Seoul most people simply call it Onda lifting.

Our own treatment page describes it as deep heat produced by the micro-vibration of water particles in the skin. Microwaves make water molecules oscillate, the oscillation becomes heat, and the heat lands in the tissue the handpiece is tuned for.

The main handpieces, Deep and Shallow, differ in how far down the energy works. DEKA recommends Deep for localized fat and Shallow for cellulite, skin tightening and the area under the chin.

One detail surprises people: at the time of writing, the manufacturer's page names body shaping and the submental area, but it does not list the face as a separate indication. Onda is offered by clinics in Seoul and other Korean cities, including Busan, and our Gangnam menu includes face sessions, so the exam matters more than the menu line.

What do 40 kJ and 60 kJ on a Korea menu tell you?

A kilojoule figure tells you the total energy delivered over the whole session, and nothing about where it goes. Energy is power multiplied by time, so a higher number usually means more area, more passes, or both. Think of it the way you'd think of milligrams on a prescription: a dose, chosen for a body.

For scale, a 2024 study treated the abdomen and thighs of 16 women by splitting each area into two 15 × 15 cm squares, about 15 minutes per square, at 130–190 W (Arrigoni et al., Journal of Cutaneous and Aesthetic Surgery, 2024). A face is a far smaller surface with thinner layers, so face and body numbers can't be compared line for line.

Fat, area and skin decide the number, not the menu

Three things move the dose more than any menu does: the tissue you can pinch, how big the area is, and how thin the skin over it is. They are checked with hands and eyes in the room, and a phone photo only hints at them.

• The pinch. Fullness under the chin or along the jowl that you can hold between two fingers is the tissue microwaves act on. When the pinch is thin, extra energy has little to work on, and a face that is already lean can start to look hollow.
• Where the heaviness comes from. A heavy lower face can be fat, or it can be cheek tissue that has slid down. Onda works on fat and on collagen in the dermis; it doesn't lift a dropped cheek back into place. That kind of sagging points toward focused ultrasound such as Ulthera, or in some faces toward a surgical opinion.
• The skin itself. Thin skin over the jawbone, reactive skin, or areas treated recently with filler or threads change the amount of heat used in one session. Filler near delicate areas has its own logic, which I set out in whose under-eyes I treat with filler and whose I leave alone.
• The size of the area. Chin only, chin plus jawline, or the whole lower face are three different jobs, even at the same kJ figure.

If you'd like the broader picture of how the device tightens skin, I covered it in how Onda tightens skin with microwaves.

Does Onda hurt, and what does the evening after look like?

Most people describe a heat that builds and eases as the handpiece moves. In the 2024 body study, average pain was 3.47 on a 10-point scale, which matches what people usually call "hot, but manageable". Our treatment page lists recovery as same-day return.

That evening, warmth, pinkness and a tender feeling when you touch the treated area are common, and they usually settle on their own. Plan a quiet dinner rather than a facial or a sauna. If your skin reacts strongly to most treatments, the notes in which treatments suit sensitive skin and how I adjust apply here as well.

For the travel calendar: consultation and treatment can happen on the same day, and we're open Mon–Fri 10:30–21:00 and Sat 10:30–17:00, closed on Sundays. If you land on a Saturday, the afternoon is short; a weekday evening slot is often easier to fit around a family visit.

Risks, and the faces Onda doesn't suit

The common effects are temporary: redness, warmth, mild swelling and tenderness in the treated area.

Less often, heat-based fat treatments can leave firm, tender spots under the skin or a patch of altered sensation that takes weeks to fade. Burns are rare but possible with any device that heats tissue, which is one reason energy settings are a medical decision. The 2024 body study observed no adverse effects in its 16 women, but that is far too few people to rule out uncommon problems.

Onda is usually a poor fit, or needs a different plan, if:

• you are pregnant or breastfeeding
• you have a pacemaker or metal implants near the area to be treated
• your face is already lean and the concern is loose skin, not fullness
• there is an active infection, open wound or flare-up in the area
• you are hoping for the change a facelift gives

And you don't need to come to Seoul for Onda if your main concern is pigment, pores or texture, which other treatments address; if the sagging in your neck and jowls is the kind a surgeon would treat; or if you are content with how your jawline looks and only came across the device online.

The evidence behind Onda is small and mostly about bodies

The 2024 study above gave four sessions 30 days apart: abdominal circumference fell from 96.59 cm to 94.55 cm on average, and fewer patients were rated as having moderate or severe laxity at follow-up. There was no control group, the paper discloses that two authors are employed at El.En. Group, and no faces were treated.

Also in 2024, an international advisory board on "Onda Coolwaves" published treatment recommendations for cellulite and localized fat in the journal Bioengineering (advisory board recommendations, 2024). Again, the focus is the body. For the face, clinical experience runs ahead of published trials.

How many sessions, and does one Seoul visit make sense?

One session is a fair way to learn how your tissue responds; a course is a separate conversation. The body study used four sessions a month apart and measured results four weeks after the last one, so changes in fat are judged over weeks, not in the mirror on the way out.

If you come to Seoul once or twice a year, a single session fits the trip, and the one-day packages that pair Onda with InMode, Titanium or Ultherapy Prime exist for people with limited days. Whether pairing devices makes sense for your face is decided at the exam, not from the package list.

A five-line note to send before you book

Writing these five lines down takes ten minutes and gives the first conversation something concrete to start from, whether you send them to us or bring them to any clinic:

• Two photos of the area in daylight without makeup, one from the front and one from the side.
• One sentence on what bothers you: fullness under the chin, a soft jawline, or heaviness in the lower cheeks.
• Any filler, threads or energy treatments in the past year, and where.
• Medical points: pregnancy, a pacemaker or metal implants, skin conditions, medicines.
• The dates you'll be in Seoul.

If you're arranging this for a parent, the same five lines work; just write them for their face and their dates.

Delphic Clinic is directly connected to Exit 3 of Sinnonhyeon Station (Line 9 and the Sinbundang Line), consultations are 1:1, and English and Chinese interpreters are on site. Send the five lines on WhatsApp, and we can go through them at the consultation; if Onda turns out not to be the right tool for that face, the exam will say so.