Collagen Skin Boosters in Korea: Re2O vs CaHA Explained

I'm Dr. Jong Hoon Lee, a director at Gangnam HERA in Seoul. I co-authored LIFTINGOLOGY: Science and Clinical Practice in Aesthetic Medicine, I'm a board member of the Korean Society for Aesthetic Surgery and the International Petit Medical Society, and I have been in practice for more than 25 years. Patients often ask me which skin booster is "the one" right now, so in this video I brought the two that I think stand out this year and explained each one: Re2O, which many Koreans know as Lituo, and CaHA.

My short answer: Re2O delivers human-derived collagen directly, so it starts working right away on fine lines and pores; CaHA stimulates your own collagen gently and steadily, so it needs fewer sessions spaced further apart and lasts a long time.

How is Re2O different from collagen boosters like Juvelook?

Juvelook and Sculptra make your skin produce collagen; Re2O contains collagen itself. When people say "collagen booster", they usually mean products like Juvelook or Sculptra — and, in a slightly different way, Rejuran. Juvelook and Sculptra enter the skin and stimulate a mild inflammatory response, and that response makes the surrounding tissue grow its own collagen. That is why we call them boosters.

Re2O is different. Collagen is already in it, so when it is injected, collagen goes straight into the skin. You are not waiting only on your body's response. If you want to understand where Juvelook's volume version fits, whether Juvelook Volume counts as a filler explains it.

Is injected collagen safe? What about allergies?

The older animal collagens caused more allergic reactions than expected; Re2O uses human-derived collagen to keep foreign-body and allergic reactions to a minimum. Collagen injections are not new. Years ago, bovine collagen was widely injected, and its allergic reactivity turned out to be higher than many expected, so its use stopped. Products using porcine collagen have also appeared more recently.

Re2O is not one of those xenogeneic collagens — collagen taken from a species other than our own. It is human-derived collagen, which is why I describe it as a product designed to minimize foreign-body and allergic reactions. As with any injectable, I still ask about your allergy and medical history first.

What does Re2O do for the skin?

In my experience it gives a clearly noticeable improvement in fine lines and pores, and you can see some effect immediately. How Re2O is prepared differs a little from doctor to doctor:

• With saline — the basic method.
• With hyaluronic acid — adds hydration, so it also helps with dryness.
• With PDRN — adds a regeneration-related ingredient for a stronger repair effect.

So the result is not only Re2O's effect on fine lines and pores; depending on the mix, you also get the hydrating effect of hyaluronic acid or the regenerative effect of PDRN. Re2O on its own already works well. One of our patients, a content creator, described her first session in a real Re2O human collagen skin booster review.

How many Re2O sessions do I need?

Generally one to three sessions about four to six weeks apart. But I don't think you have to commit to a fixed course. You can have one session, look at how your skin responds, and then decide the interval. For international patients that flexibility matters: one session on this trip, and the decision about a second one can wait until you've seen the result at home.

What is CaHA, and how does it work?

CaHA stands for calcium hydroxyapatite — a collagen stimulator like Sculptra or Juvelook, but it works in a different way. At HERA we use DCLASSY CaHA a great deal. Calcium is one of the components of our bones and teeth, and CaHA induces collagen in two ways:

1. Calcium ions help trigger collagen production.
2. Tiny round microspheres physically stimulate fibroblasts, the cells that make collagen.

Juvelook and Sculptra build firmness through a kind of inflammatory response. CaHA takes a different route, so I describe it as a collagen inducer with a slightly different character. Here is the comparison I gave in the video: if Sculptra stimulates collagen strongly, like stoking a bonfire, Juvelook is more stable, and CaHA is more stable still.

How often is CaHA given, and how long does it last?

Usually once or twice, spaced at least two and up to about three months apart — and the effect lasts around a year and a half or more. Compare that with Sculptra or Juvelook, which are typically given about three times at four- to six-week intervals.

The longer gap is not because CaHA adds a lot of volume. It doesn't. A large increase in volume would mean the stimulation was strong — and strong stimulation is harder to control. CaHA instead stimulates collagen gradually, and that moderate level of stimulation keeps going for a long time. Individual results vary, and your plan is confirmed at consultation.

Where does CaHA work best?

In two places filler handles poorly: fine lines around the smile and marionette areas, and vertical neck lines.

Shallow lines around the folds

Fine lines around the nasolabial and marionette areas are often too shallow for filler. In those cases I spread small amounts of CaHA lightly just beneath the dermis, and the fine lines improve slowly and gradually. For deeper folds that do need filler, see a plastic surgeon's answer on filler for nasolabial folds.

Vertical neck lines

Horizontal neck lines are usually treated with filler. Vertical lines, however, often don't respond well to that. Diluting CaHA and spreading it in small amounts can make those areas firmer as well.

The honest limits

Neither product is a lift, and neither replaces filler where real structural volume is needed. Re2O improves skin quality and CaHA builds firmness gradually; if your main concern is sagging, a lifting treatment may be the right first step, and I will tell you so. Redness, small bumps or bruises at injection points can appear and usually settle within days. And because skin responds differently from person to person, I can't promise a specific amount of change — I can explain what I expect after I've seen your skin.

If you are torn between several boosters, why one well-chosen booster is usually enough is a good place to start. If you have questions about any other skin booster, leave them under the video and I'll prepare a detailed answer.