It is the same polycaprolactone, so what is different between the liquid form and the microsphere-based form

Let us put them side by side first.

That is, the microsphere-based form is a way of “placing a limited amount subcutaneously”, and the liquid form is a way of “spreading a little at a time, superficially, over many points”. Even with the same ingredient, the problem being addressed is different — the former is on the side of supporting a hollowed place, the latter on the side of addressing the skin itself over a wide area.

We have seen some overseas distribution pages give the microsphere size as “400 to 600 µm”, but the peer-reviewed literature and the manufacturer's material give 25 to 50 µm consistently. It appears to be an error in the distributor's labelling.

This family has data that scarcely exist for the other collagen booster families. It is a biopsy study in which human skin was actually taken.

Kim JS, Aesthetic Surgery Journal 2019;39(12):NP484 — 13 Asian women (mean age 38.7). A PCL preparation was diluted and put into the dermis, with the untreated temple on the opposite side taken as the control.

In another biopsy study, the PCL particles remained intact even at 13 months with collagen formed around them (2 patients, dermal injection).

There is also a 24-month randomised controlled trial (40 patients, nasolabial folds). At the 12-month point about 90% in both arms maintained improvement, and no complications, including nodules · granulomas, were reported. However, the control arm in this trial was not a placebo but a different formulation of the same PCL.

Post-marketing data

These are the post-marketing safety data published by the manufacturer (for sales up to December 2015).

A total of 323,726 syringes sold, 155 adverse events — 0.048%, that is, 1 case per 2,089 syringes. Oedema 0.017%, lumps · nodules 0.016%, inflammation · infection 0.002%.

Laying over this a retrospective study that followed 780 patients · 1,111 treatments over 3 years makes the picture clearer still — persistent oedema 4.5%, bruising 2.7%, temporary lump 0.45%, and 0 cases each of nodule · granuloma · infection · intravascular injection.

Post-marketing data are based on spontaneous reporting and so run lower than the real incidence. The 1,111-treatment study is also single-centre retrospective data, and its denominator is treatments rather than patients. Even so, the point that a denominator of 320,000 syringes is itself a rare size in this field has its worth.

The liquid form is a comparatively recent arrival. We will write down what we verified, as it is.

• Brito K & Ong D, Annals of Case Reports 2023;8(4):1371 — 2 patients (women aged 28 · 32), 5 points per side × 0.2 mL with a 31G needle, 2 sessions at 4-week intervals, 12-week follow-up. Global improvement rating: patient 4.0 · injector 3.0. There was local swelling and erythema lasting under 48 hours, and 1 patient needed an oral steroid. There was no bruising · lump · pigmentation · vascular occlusion · granuloma · nodule · infection
• 1 case report — use for skin laxity in a patient with pseudoxanthoma elasticum (Journal of Cosmetic Dermatology). We verified only as far as the abstract
• Animal data — increased dermal thickness and collagen in an ultraviolet photoaging mouse model

Biopsy data on human skin injected with liquid PCL we did not find. The microsphere-based form has biopsies at 1 year · 4 years · 13 months, but the liquid form has no corresponding data.

The claim that the aim is different

The manufacturer and related contributions explain the liquid form like this — “once injected it spreads evenly under the skin, so it cannot be regarded as a filler”, that is, that it targets not local volume but the dermal matrix as a whole.

This direction is itself consistent with the difference in composition above (no beads, superficial injection at many points). However, there are as yet no data confirming this in human tissue. So when we use the liquid form we do not tell you that it “creates volume”; we tell you it is “a choice that addresses the skin over a wide area”.

PCL degrades in two stages. This structure is the substance of the phrase “the duration is designed”.

1. Stage 1 — non-enzymatic hydrolysis. Water breaks the ester bonds and the molecular weight falls gradually. Yet at this stage the mass and volume of the bulk are maintained as they are. The chains merely shorten; the substance remains
2. Stage 2 — enzymatic degradation. Once the molecular weight falls to about 3,000 to 5,000, from then on the mass decreases and it is absorbed by the normal metabolic pathway

So the longer the chains put in at the start, the longer stage 1 (the period in which the volume is maintained) lasts. This is the basis on which the microsphere-based product range is divided into S · M · L · E and marked as 1 year · 2 years · 3 years · 4 years respectively.

An important qualification attaches here. The manufacturer itself states that the durations for L and E are “extrapolated from the clinical data for S and M with the known degradation behaviour of PCL applied”. That is, the 3 years · 4 years are not figures measured by a clinical trial directly. And as we shall see below, L · E are not approved in Korea.

What of the duration of the liquid form? The manufacturer writes that “it usually takes 6 to 12 months for PCL to break down in the body”, but this is a statement about the period over which the substance disappears, not data measuring in humans how long the clinical effect lasts. Data measuring the duration of effect of the liquid form in humans we were not able to verify.

Since in article 27 we wrote “look the approval number up for yourself”, here we will show exactly what we verified.

The microsphere-based form — domestic approval verified

The original text of the approved intended use runs like this — “used for the temporary improvement of facial wrinkles in adults through physical restoration by injecting polycaprolactone subcutaneously”.

What we wrote in article 27 is confirmed here as well. The wording of the approval is “physical restoration” and “temporary improvement”, and “collagen production” is not in the approved intended use. The collagen story is an area handled not by the approval but by research.

‘Suheo’ means import + approval. The detail is written up in Jeheo · suheo · certification, what one line of approval number can and cannot tell you.

The liquid form — we were not able to verify it in the original

Several media outlets reported that it received MFDS approval in Korea during 2025, and in May 2026 there was a report that it had received product approval from the Taiwanese food and drug authority. European CE certification has also been reported.

Yet the product name · class · approval number · date of approval we were not able to verify from primary sources. We were not able to access the MFDS lookup system directly, and the manufacturer's official English-language site still states “domestic approval in progress”, so it appears not to have been updated.

That is why the approval number of the liquid form is not written in this article. It is because copying across a number floating about on the internet can be wrong. At a consultation we check it together with you against the markings on the actual product box — under Article 20(3) of the Medical Devices Act the number must be written on the container.

This is the part of this article that has to be written most honestly.

A study directly comparing liquid-form PCL and microsphere-based PCL in humans is not verified. Neither a split-face comparison nor a randomised allocation, there is none in any form.

The PCL comparative studies that are verified are all on other axes.

• Microsphere-based PCL versus hyaluronic acid — randomised · blinded · split-face
• Microsphere-based PCL versus another grade of the same microsphere-based form — 40 patients, 24 months
• Microspheres of a microsphere-based PCL versus other PCL microspheres — preclinical, mouse

So neither “the liquid form is better” nor “it is the same ingredient, so they are similar” has ever been tested. What can be compared is not the outcomes but the thickness of the evidence itself.

This does not mean “the liquid form is bad”. It has not been long on the market, and the data that take time have not yet accumulated. But it is better to make your choice knowing this difference, is what we think.

① It does not dissolve with hyaluronidase

PCL is a polyester made up of ester bonds. Hyaluronidase is an enzyme that acts only on hyaluronic acid, so PCL in both formulations cannot be dissolved and reversed.

So for this family the layer and the amount at the time of the first injection matter more than for the hyaluronic acid family. If a problem arises, one looks at the location by ultrasound and comes to rely on a topical steroid or on physical measures. It is why, when we use PCL, we tell you beforehand which layer we will put how much into.

② The long-lasting bruising reported with the liquid form

There is one recent piece of data on the liquid form, which we write down as it is.

Byeon H et al., Clinical, Cosmetic and Investigational Dermatology 2026 — 7 cases of bruising lasting several months after injection of liquid PCL. A total of 1 to 4 mL, 23G · 25G cannula, from the dermis to the subcutaneous layer. It appeared mainly in areas rich in blood vessels such as the infraorbital region.

The authors put forward two hypotheses — ① that pigment molecules formed as haemoglobin breaks down may be temporarily trapped within the structure made by the liquid PCL ② light scattering (Tyndall) due to the polymer in a superficial layer. For treatment, pigment lasers · heat-based devices · mechanical dispersion and the like were used, and all the cases resolved completely.

There are two reasons we write this paper down. First, because it is grounds for taking the layer deeper and dividing the amount when using the liquid form in this area. Second, because we must also tell you that in the end they all got better.

To add to it, case reports of nodules · granulomas with the liquid form were not verified within the scope of our search. But the nodule rate of 0.016% for the microsphere-based form is a figure that came out of 320,000 syringes, and the liquid form has as yet no corresponding denominator. “No reports” and “does not happen” are different things.

What we say in the consulting room is short.

If a hollowed place has to be supported, the side with the thicker body of data is the safe choice. If the skin itself over a wide area is the problem, it is true that the liquid form is designed for that purpose, only you should choose knowing that it has a body of data still in the course of accumulating.

To look at the family as a whole, see The things called ‘collagen boosters’, and for the story of what happens when a nodule forms, Nodules that form after a procedure.

Written and reviewed by Lee Chi-Hak, MD, medical director of Miso Clinic in Daegu, South Korea. Every study cited above is given together with its design, its size and the limitations the authors themselves recorded, and where we could not find data, we have said that we could not find any.