Are Fillers Safe? A Korean Dermatologist Answers 3 Common Fears

I'm Dr. Hongseok Kim, a board-certified dermatologist with 21 years of practice and the medical director of VOS Dermatology Clinic in Gangnam, Seoul, right in front of Dosan Park. I see every patient myself, from the first consultation to the treatment.

Are fillers safe? Many patients ask me this as a Korean dermatologist, and some reject filler the moment I mention it: "No, I don't want filler." Their worries are usually the same three: that filler stays in the face, that it moves, and that a skin booster must be the safer choice. This page is based on my YouTube video from February 2024; I rewrote it for readers abroad. The video above can be watched with translated captions.

What filler is, and why it got a bad reputation

Filler is any substance injected to build volume in the face, and the type most people mean is hyaluronic acid filler.

In the widest sense, calcium-based fillers such as calcium hydroxyapatite, and polymer products such as Juvelook Volume and Sculptra, also create volume (in the video at 00:41). We do not usually call those fillers; they are grouped as biostimulators or skin boosters. When people say filler, they almost always mean hyaluronic acid filler.

So why do so many people think of filler as a harmful ingredient (in the video at 01:23)? Part of it came from a widely shared video about filler side effects. Another part is the rise of skin boosters and biostimulators, which help the skin make its own collagen. Next to them, hyaluronic acid filler started to look like a foreign material that only fills space, and collagen-building products looked like the good option. That is not entirely wrong, but it misses an important point.

Fillers and boosters do different jobs

Skin boosters change the face gradually over repeated sessions, while filler can correct a specific area faster.

Biostimulators and skin boosters are designed for natural change that builds up over several treatments (in the video at 02:27). They are weaker when the goal is to correct one area, because supporting a structure requires collagen to form and fill in, and that takes a long time. If you only want gradual, natural improvement, boosters work well. If you want a particular area improved sooner, that slowness becomes a real drawback, and that is when filler makes sense.

Hyaluronic acid itself is already part of our skin (in the video at 03:11). Plain hyaluronic acid injected into the skin is broken down almost immediately. To slow this, a cross-linking agent binds the molecules together. Less cross-linking gives a soft, fluid gel; more cross-linking gives a firm one. Ask yourself: would you rather an injection last two weeks or six months, and would you rather get one session or five or six for the same result (in the video at 04:11)? Most people choose six months and one session, and that choice is essentially an argument for cross-linked filler. My guide to what Korean fillers are made of and who each suits explains the gel types in more detail.

Why the right gel for each area matters

Unnatural results usually come from imagining, or using, the wrong type of filler for the area.

A nose or chin filler must hold its shape; if it spreads out, the treatment is pointless (in the video at 03:51). Under the eyes, in the nasolabial folds and along marionette lines, filler works differently: it supports tissue from below, so that what is sagging from above does not drop further and may lift slightly (in the video at 05:14). A firm gel cannot be used under the eyes, a very fluid gel will not support the nasolabial or marionette area, so a medium gel is used there, and firm gel suits the nose, chin and temples, where expression changes little (in the video at 05:55). The amount also differs by position. Many people picture only the firm nose-and-chin type, so they assume any filler in their face will look unnatural.

Does filler stay in the face?

Filler is meant to stay for a while, but hyaluronic acid filler can be dissolved if needed.

People sometimes tell me they heard filler stays in the face (in the video at 06:56). It does, in the sense that lasting a month rather than two weeks is the whole point. The real worry is that it might never break down. Hyaluronic acid filler can be dissolved with an enzyme called hyaluronidase (in the video at 07:17). The situation where lingering becomes a genuine problem is different: long-lasting calcium-based fillers such as calcium hydroxyapatite, used in very large amounts, can harden like bone and may need to be removed surgically. There are also techniques that deliberately inject a large amount in one go so it clumps and lasts longer (in the video at 07:37). If filler ends up firmer or more persistent than expected, hyaluronic acid filler can be dissolved, so this alone is not a reason for panic. My overview of common myths about Korean dermal filler covers similar questions.

Can filler move after treatment?

Yes, filler can shift slightly, which is why you should not massage or rub the area for about three days to a week afterwards.

That is the basic aftercare rule (in the video at 08:19). Gravity can also let filler settle a little lower over time. What I would not expect is for filler injected in one spot to end up somewhere far away on the face (in the video at 08:48). The face contains fat, muscle and many ligaments that attach to the skin, and these divide it into compartments. Filler, like fat and sagging tissue, tends to move within its own compartment rather than cross into another one.

Filler or skin booster: how I decide

For overall, natural improvement I prefer skin boosters; for a specific area with significant volume loss, a small amount of filler can be the better choice.

When I listen to some patients who rely only on boosters, they need repeated sessions of a product such as Juvelook Volume in the same area again and again (in the video at 09:29). If a small amount of filler supports that area first and boosters are added afterwards, the number of sessions can drop and results can appear sooner. In my practice I see the filler market growing again for this reason: people moved to skin boosters because they disliked filler, then found some concerns boosters could not solve (in the video at 10:12).

For natural, overall change I still think boosters such as Juvelook Volume do better, and Juvelook is the version for fine lines and texture. Where volume has dropped a lot and needs correction, filler can actually be safer, and that is the conclusion I have reached from consulting patients and seeing their results (in the video at 10:53). Thin areas such as around the eyes are fragile; one treatment heals with less injury than the same injection repeated three, four or five times, because each session is itself a stimulus that can weaken the tissue (in the video at 11:13). My notes on whether biorevitalization is just a filler explain how the two categories overlap.

Thinking of filler as simply bad is black-and-white thinking. The doctor decides whether to use a little filler and which type, soft and natural or firm and long-lasting. Avoiding it entirely can mean more cost, more time and a result that falls short of what you wanted. No injectable is free of risk, and the video focuses on these common worries rather than every possible complication, so ask the doctor who will inject you about the specific risks for your area. If you are planning treatment on a short trip, my guide to six filler risks to weigh before a short trip may help, and you can read creator experiences at VOS. Before booking, send us on WhatsApp a daylight photo without make-up, your travel dates and anything injected in the past year.

Results and recovery vary from person to person, and whether filler, a booster or both suits you is decided at a consultation.

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Results, swelling and recovery vary from person to person. This page is general information from VOS Dermatology Clinic based on Dr. Kim's video and does not replace an in-person consultation.