Filler is an injection that places material under the skin or at that depth to fill a hollowed site. They share the same name, but when the material placed differs, when volume is felt and whether it can later be dissolved also differ.
3-line summary
Fillers split by material, such as hyaluronic acid (HA), CaHA (calcium hydroxylapatite), and PLLA (poly-L-lactide), and they also split by whether volume is immediate or settles over several sessions.
Hyaluronic acid can be corrected with a dissolving enzyme, and that enzyme does not apply to CaHA or PLLA.
The nose, forehead, and glabella have often appeared in vision-change cases, and if a vessel is blocked, it can lead to skin necrosis or reduced vision.
Filler materials differ
The criterion in consultation is not a trending product name but today’s material. First you separate whether it is a gel made so a moisture material already found in the skin lasts longer, a formulation mixing calcium particles into a gel, or particles mixed with water before injection.
| Item | Hyaluronic acid (HA) | CaHA | PLLA |
|---|---|---|---|
| What is placed | A gel made so a moisture material lasts longer | Calcium particles + gel | Biodegradable particles mixed with water |
| When volume is felt | Immediately after placement | From immediately after placement | Gradually over several sessions |
| Duration | Split by product and site | Around 1 year~1 year and a half in a literature review | Up to around 2 years in a literature review |
| Dissolving enzyme | Applies | Does not apply | Does not apply |
| Frequently reported reactions | Swelling·bruising; a vascular emergency | Nodules in most reports | Nodules·firm granules |
※ Duration is the range compiled by a review that pooled literature used on the face. Among the review authors is a researcher affiliated with a clinic’s research and development.
Hyaluronic acid filler
Hyaluronic acid filler places a gel made so a moisture material lasts longer. Volume tends to be felt right at the placement site. Duration is split by product and site.
This material alone can be reduced with a dissolving enzyme. In a study that dissolved hyaluronic acid placed on the back with the enzyme, sites treated with the enzyme decreased faster than sites given saline only. Dissolution speed differs by product. This enzyme is also used in a vascular emergency, but a literature review pooling vision-change cases did not identify a confirmed method that restores vision.
CaHA and PLLA
CaHA is a filler that mixes calcium particles into a gel. Literature reviews classify this formulation toward stimulating collagen along with volume.
In a literature review pooling CaHA adverse-event reports, nodules were the majority. Nearly half of the reported nodules arose at sites with a lot of movement, and many were not visible on the surface and resolved without treatment.
PLLA is particles mixed with water before injection. Rather than matching volume in one session, it is placed split across several sessions. Firm granules are reported, and dilution and placement depth are reviewed together.
In a survey pooling 55 collagen-stimulator filler complications, cases in which the dissolving enzyme helped were formulations mixed with hyaluronic acid. That enzyme does not apply to sites with CaHA or PLLA only.
When looking at site and material together
You do not choose the material alone; you also look at vessels at the placement site. In a literature review pooling published vision-change cases, the nose, forehead, and glabella appeared often, and hyaluronic acid accounted for a substantial share of those cases. This is not because hyaluronic acid is more dangerous, but because that material is widely used. In the same review, the share in which vision did not recover was high.
| Site | Frequently used material | Points to check together |
|---|---|---|
| Nose·forehead·glabella | Hyaluronic acid is common | Sites where vision-change cases clustered. There is room to dissolve with the enzyme |
| Lips | Hyaluronic acid | A lot of movement, so a softer gel is often chosen |
| Cheeks·jawline | All three materials reviewed | Immediate volume versus waiting across several sessions |
| Tear trough | Hyaluronic acid is common | Skin is thin, so shallow placement may show through |
On the injection day, swelling·bruising·redness are common. If the skin turns pale or purple, pain is severe, and vision blurs, contact the clinic that performed the procedure immediately.
What to ask as written in consultation
Material, site, and prior procedure history are matched in one sitting. Read the items below and ask them as written in the consultation room.
- □ Is today’s material hyaluronic acid, CaHA, or PLLA?
- □ Can a dissolving enzyme be used with this material?
- □ Is the plan to match volume in one session, or to wait while splitting across several sessions?
- □ Do you know the filler ingredient placed at this site in the past?
- □ Is this a site, such as the nose, forehead, or glabella, where vision-change cases have been reported?
Frequently asked questions
Q1. Does a filler procedure hurt?
Needle-entry pain and same-day swelling·bruising are common. Pain is often reduced with anesthetic cream or an anesthetic mixed into the product. Material is not chosen by pain alone.
Q2. How many sessions?
Hyaluronic acid and CaHA are often designed to match same-day volume. PLLA is placed split across several sessions, and later intervals are set by looking at product instructions and the skin’s response.
Q3. How long does it last?
Duration is a value compiled around how long volume remains visible at that site. It is split by product, site, and the person’s metabolism.
Q4. Can it be done with another filler?
If different materials overlap at the same site over a short interval, it becomes hard to tell what remains, and the option to dissolve with the enzyme narrows. If the previously placed ingredient is disclosed first, interval and site can be divided in the plan.
Q5. Who should not receive it?
Infection at the treatment site and hypersensitivity to the ingredient are among the contraindications. Pregnancy or breastfeeding, anticoagulant or antiplatelet use, and a history of severe allergy are disclosed before the procedure.
Results, duration, and suitability vary with individual skin condition, age, and lifestyle, and the same outcome cannot be guaranteed.
Procedures may cause temporary redness or swelling, and contraindications may apply, so please confirm these during your consultation.
This article is general information and does not replace individual medical care. Please confirm diagnosis and treatment suited to your condition during a consultation.
Sources
- Study dissolving hyaluronic acid filler with an enzyme (PMID 28498207) — Confirmation scope: abstract. Commercial hyaluronic acid placed on the backs of 15 participants was compared with enzyme or saline, and the observation site is the back. 14-day observation.
- PLLA·CaHA facial literature review (PMID 41184662) — Confirmation scope: abstract. 14 papers from 2010–2024. Duration summarized as PLLA up to 25 months, CaHA 12–18 months. Among the authors, clinic research-and-development affiliation. Individual conflicts of interest in the original text could not be confirmed from the abstract.
- Literature review of vision-change cases after filler (PMID 38630871) — Confirmation scope: abstract. 365 published cases from 2018–2023. Share of nose, forehead, and glabella; hyaluronic acid 79.6%; no vision recovery 68.2%. Only published cases were pooled, and incidence was not calculated separately. No retraction or expression of concern.
- CaHA safety literature review (PMID 28247924) — Confirmation scope: abstract. 21 papers from 2004–2015, 5,081 procedures·2,779 people. Of 173 adverse events (3%), 166 were nodules. A narrative review by a single author.
- Survey of 55 collagen-stimulator filler complications (PMID 38693639) — Confirmation scope: abstract. Survey of ultrasound specialists in Brazil. Nodules 89.1%. Cases in which the enzyme helped were formulations mixed with hyaluronic acid. Not an incidence study, but a collection of reported complications.
- U.S. approval safety and effectiveness summary, Radiesse — Confirmation scope: PDF body. A formulation with CaHA particles suspended in a water·glycerin·carboxymethylcellulose gel; wrinkle grooves including moderate to severe nasolabial folds. A document separate from the Korean approval scope.
- U.S. approval safety and effectiveness summary, Sculptra — Confirmation scope: PDF body. A formulation of PLLA mixed with water for injection. VEGA study in people with infection who showed facial fat loss (96 weeks, many 4–5 sessions, 2-week intervals). The aesthetic indication expansion and the study population differ.
Related reading
Sources
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