Filler dissolving not working:
why filler can remain after hyaluronidase

What patients tell Dr Sin Yong

Many patients who come to see Dr Sin Yong about filler problems tell him they have tried almost everything else and had given up hope.

Having tried other treatments does not, on its own, rule out further options. What can be done depends on what the scan shows: what the material is, where it sits and how much of it is left. That is why a second look starts with ultrasound rather than with another dose of enzyme.

Why filler can remain after hyaluronidase

Hyaluronidase is an enzyme that breaks down hyaluronic acid. It does nothing to other fillers, and it only acts where it reaches. Published reviews also note that hyaluronic acid products differ in how readily the enzyme breaks them down, which is one reason doses are staged and reviewed (Landau 2015; Kroumpouzos and Treacy 2024). The table sets out the common reasons filler seems to stay.

Swipe sideways to see the whole table.

Filler that has been in place for years can also change. Hyaluronic acid breaks down slowly and unevenly, and other materials are cleared by the body through different, slower processes (Wollina 2024). A lump that appears months or years later is a symptom rather than a diagnosis, and a full history and assessment come before any treatment (Convery 2021).

“A biostimulator cannot be dissolved. That single fact should shape every decision about using one.”

Dr Sin YongOn why some fillers do not dissolve

What a second look with ultrasound shows

High-frequency ultrasound shows the layers of the face and what sits between them. Hyaluronic acid, calcium hydroxylapatite and polycaprolactone tend to look different on the scan, and the scan shows how deep a deposit sits and whether blood vessels run close to it (Wortsman 2015; Schelke 2018). Dr Sin Yong performs the scan and any injection himself.

Seeing the deposit changes how the enzyme is used. In a study of blocked-vessel emergencies, placing hyaluronidase into the filler seen on ultrasound used a mean of 122.5 units, against 1,519.4 units when the whole region was flooded (Schelke, Aesthet Surg J 2023). That study was about emergencies, but the principle of aiming at what can be seen applies to planned dissolving too.

When hyaluronic acid remains: targeting it again

If the scan shows a deposit that looks like hyaluronic acid, it can be dissolved again, this time into the deposit itself. A small dose is placed, the area is reviewed at about 48 hours, and more is added only where filler remains (King 2018). Allergy history is checked again, including any reaction to earlier doses and any bee or wasp sting allergy, with a skin test where there is concern.

Dissolving more than was in excess can leave an area looking hollower than expected, which is why the dose is staged. Refilling, if it is wanted at all, waits at least two weeks and until the swelling has settled (Murray 2021). The steps are set out in filler dissolving in Singapore, with what to expect afterwards in after filler dissolving.

When the filler cannot be dissolved

Sculptra (poly-L-lactic acid), Ellansé (polycaprolactone), Radiesse (calcium hydroxylapatite) and Juvelook (poly-D,L-lactic acid) are not broken down by hyaluronidase (Lin and Christen 2020; Wollina 2024); in Juvelook only the hyaluronic acid carrier is. If one of these was treated as hyaluronic acid, the enzyme had nothing to act on. Nodules after collagen-stimulating fillers are described in a published case series, and they behave differently from hyaluronic acid lumps (Ianhez 2024).

For material that cannot be dissolved, Dr Sin Yong uses the Sculpting mode of Time Freeze Laser LCLR® for nodules large and small, without an incision. How each person responds varies. More is in the Sculpting mode of Time Freeze Laser LCLR®, Ellansé removal and correction, Sculptra lumps and nodules and Radiesse lumps.

When it is not filler at all

Not every fullness after filler is filler. Swelling over the cheeks or under the eyes can come from fluid that the tissue holds. Published imaging work suggests that filler pressing on the veins and lymphatic drainage around the eye can play a part; in that case series the swelling improved after the filler was removed under ultrasound guidance (Schelke, J Cosmet Dermatol 2023). Eye bags, loose skin, fat and the natural shape of the face can all look like leftover filler, particularly in photographs taken in overhead light.

Dissolving cannot change eye bags, loose skin, fat or facial shape, so the examination and scan come first. Where the cause is laxity or fat rather than filler, the options are different, and they are discussed at the same visit. See under-eye filler dissolving and pillow face.

What to bring to a second assessment

• Product names, sticker cards or invoices from earlier treatments, if you have them.
• Approximate dates of each filler treatment and each dissolving visit.
• Which areas were treated, and with what, as far as you know.
• Any reaction to earlier hyaluronidase, and any allergies.
• Photographs from before any filler, which help show your own facial shape.

None of this is required. Filler done at other clinics in Singapore or overseas is assessed in the same way; see a second opinion after treatment elsewhere.

When not to wait

Urgent: a change in vision or eye pain after filler means calling 995 or going to the nearest emergency department now. Skin that turns pale, dusky or mottled, or pain that is getting worse, needs urgent assessment by the doctor who injected you, or at A&E. See the warning signs of a blocked blood vessel after filler.

A lump that becomes red, hot, painful or quickly larger may be inflamed or infected and needs a prompt medical review rather than a planned dissolving visit.

How Dr Sin Yong approaches a second look

Dr Sin Yong sees every patient himself on Orchard Road, scans before anything is planned and performs any injection or laser treatment himself. He does not add more product to hide a lump, and he does not repeat a treatment that has already failed without first finding out why it did.

He developed the Time Freeze Laser LCLR® protocol and has been invited to share his clinical expertise internationally, including as a Global Key Opinion Leader. Whatever the history, the plan follows what the scan shows, and how each person responds varies.