After Rejuran Comes ONDA

“Doctor, then how many kJ of ONDA should I get?”

Yes. Just when we escaped the world of cc, the world of kJ was waiting for us.

Forty, sixty, eighty—just looking at the numbers, it is hard to tell what the differences are or which option is right for you.

So here it is: Part 2 of the Key Doctor’s treatment dosage series—Face ONDA kJ Edition. Once again, I will try to make it as easy and entertaining as possible. By the end, you may be the one walking into the consultation room saying, “I look like a 60 kJ case, don’t I?”

So, What Exactly Does ONDA Do?

ONDA is a device that uses microwave energy. The word “microwave” probably makes you think of a microwave oven. Yes, it is a very, very distant relative—but don’t worry, we are not cooking your face. (And please don’t bring any eggs.)

What makes ONDA unique is that it delivers energy beneath the skin’s surface, targeting the layer where facial fat—such as cheek and under-chin fat—is located. At the same time, its cooling system keeps the skin’s surface comfortable.

Cool on the outside and hard at work underneath—it is very good at living a double life.

This is how I usually explain ONDA:

“It is like sending the fat layer of your face to a Korean sauna.”

When you visit a sauna, the warmth reaches deep into your body and makes you sweat. Similarly, ONDA delivers heat to the fat layer to help refine areas such as the cheeks and under the chin. The heat stimulation may also help improve skin firmness.

That is why ONDA is popular among people who want to reduce unwanted facial fullness while creating a more defined facial contour.

What Exactly Is a kJ?

A kJ, or kilojoule, is a unit of energy. You may remember hearing about it in science class—but probably not much else. That’s okay. I forgot it as soon as the exam was over, too.

Simply put, kJ refers to the total amount of energy delivered during the treatment. If ONDA were a sauna, kJ would be similar to how long you stay inside.

Here is the important point: increasing the kJ does not mean applying more intense heat to one spot. It is more like staying in the same-temperature sauna for longer and covering more areas thoroughly.

Therefore, a higher kJ setting generally allows the practitioner to treat a wider area in greater detail.

Now, let me show you the three sauna passes.

Comparing the 40 kJ, 60 kJ, and 80 kJ Sauna Passes

40 kJ: The Quick Soak Course — “I’ll Just Warm Up a Little”

This option may be suitable for people who are trying ONDA for the first time and want to know what it feels like. It may also work well if only one specific area—such as the double chin or jawline—is bothering you.

It can also be a good choice when you do not have much facial fullness but would like to refine your facial contour slightly.

Think of it as saying, “I’ll just have a quick soak today.” It is light, but it can still leave you feeling refreshed.

60 kJ: The Classic Sauna Course — “I’ll Do One Full Round of the Lower Face”

This option is often recommended when the cheeks, jawline, and double chin are all areas of concern.

It is a balanced choice for people who feel that treating just one area would not be enough but do not want anything overly extensive.

Many people come in saying, “I was planning to get 40 kJ…” Then they look in the mirror and say, “Actually, this area too…and maybe here as well…” before deciding on 60 kJ.

It is the moment your face says, “Surprise—I was hiding some fullness here too.”

80 kJ: The Full Sauna Package — “I’ll Have the Sikhye and Baked Eggs Too”

This amount may be suitable when facial fullness is distributed across a wider area or when you want to address the cheeks, jawline, and double chin more thoroughly in one session.

It can be a solid option when facial fullness makes the face appear larger or when a broad area needs detailed coverage.

It is the full sauna experience—the course for people who want to walk out feeling much more refreshed than when they went in.

Is a Higher kJ Always Better?

I knew this question was coming. I received the same question after my Rejuran post: “Isn’t 6 cc automatically the best?”

Human nature really is universal.

If you stay in a sauna for three hours, will you lose three times as much weight? Of course not. You will probably just feel dizzy and start desperately searching for a cup of sikhye.

ONDA works in a similar way. If there is not much facial fat to address, simply increasing the energy does not guarantee proportionally better results.

What matters more are these three factors:

• How much facial fat you have and where it is located
• The thickness and firmness of your skin
• Whether your goal is subtle contour refinement or more extensive volume reduction

That is why two people in their thirties may need completely different amounts. For one person, 40 kJ may be sufficient, while another may be better suited to 80 kJ.

Just because your friend received 80 kJ does not mean 80 kJ is automatically right for you.

One more thing: ONDA is generally not the type of treatment that produces an instant “Ta-da!” transformation. Facial contours typically become more refined gradually over time.

Rather than rushing to increase the kJ, I recommend starting with an energy level that suits your face and considering additional sessions at appropriate intervals if needed.

The 3-Second Summary for Busy Readers

I know some of you scrolled straight down and stopped here. Don’t worry—I see you. Reading just this section means you are already halfway there.

Please remember that this table is only a general guide. The final energy level should be determined after evaluating the distribution of facial fat and the condition of your skin in person.

Frequently Asked Questions in the Consultation Room
(feat. Honest Answers, Part 2)

Q. Is it very hot or painful?

Honestly, saying, “You won’t feel anything at all,” would not be truthful.

You may feel warmth building beneath the skin, and some areas may occasionally feel briefly sharp or tingly. However, because the skin’s surface is cooled throughout the treatment, most patients say it is more tolerable than they expected.

It is a little like the first three seconds after stepping into the hottest room at a Korean sauna.

Q. Can I return to my daily routine immediately afterward?

Most people can return to their usual activities right away.

The treated area may look slightly red or swollen, but this generally settles relatively quickly. However, if you have an important photo shoot or event coming up, I recommend leaving a few days between your treatment and the event.

Q. Can I see results after just one treatment?

Some people notice changes after one session. Depending on the condition of your face, however, we may recommend several treatments at appropriate intervals.

The ideal number of sessions is best determined during an in-person consultation.

Q. Can ONDA be combined with other lifting treatments?

Yes. ONDA is often planned in combination with lifting treatments such as Ultherapy, which target different tissue layers.

You can think of it as dividing up the work: ONDA focuses more on the fat layer, while other devices address other layers.

The most suitable combination should be selected after evaluating your facial structure and skin condition.

Q. Can I start with 40 kJ and increase it next time?

Of course!

Starting with 40 kJ to see how your face responds and then adjusting the energy level at your next session can be a good approach.

It is just like trying a quick soak first and choosing the classic sauna course next time if you enjoyed it.

※ Responses to treatment and levels of satisfaction may vary depending on each individual’s skin condition.

※ Detailed treatment plans and aftercare instructions should be determined following consultation with a qualified medical professional.