Forehead filler in Korea reshapes a flat, sloping or dented upper face by laying gel on the frontal bone, most often hyaluronic acid and sometimes calcium hydroxylapatite. The material matters more here than in most zones: hyaluronic acid can be broken down by the enzyme hyaluronidase, while calcium hydroxylapatite cannot. Around Hongdae, consultation and injection usually fit into one appointment, with numbing first. Swelling may last a week or more and can drift toward the eyelids. Because forehead arteries connect to the eye, vision loss after filler has been reported in the medical literature, so technique and emergency readiness deserve real questions.
Guide
Reversible or not: hyaluronic acid against calcium hydroxylapatite
Two families of product appear in forehead studies. Hyaluronic acid is a cross-linked gel the body slowly absorbs. Calcium hydroxylapatite, sold as Radiesse by Merz, is a denser paste of mineral microspheres that also prompts collagen growth.
The practical gap is reversal. If a hyaluronic acid result looks lumpy, or a vessel is compromised, hyaluronidase can dissolve much of the gel within hours. No enzyme does the same for calcium hydroxylapatite, so many first-timers prefer the option that can be undone.
| Point | Hyaluronic acid gel | Calcium hydroxylapatite |
|---|---|---|
| Can an enzyme dissolve it | Yes, hyaluronidase | No |
| How it adds volume | Gel fills space and holds water | Microspheres fill, then collagen forms |
| Forehead study on this page | Rauso, 2025 | Kim, 2018 |
Guide
Why forehead doses are larger than people expect
The forehead is a broad, curved surface, so small amounts rarely change it. In a 2025 retrospective study in the Journal of Craniofacial Surgery, Rauso and colleagues followed 38 patients, 36 of them men, given a soft, low-elasticity hyaluronic acid gel injected straight onto the bone. The mean volume was 16 mL. The authors reported no complications, average satisfaction of 91 out of 100 at 12 months, and stable contours up to 36 months.
Read those figures with care: it was one group without a comparison arm, mostly men seeking a fuller brow. Many people want a gentler change, which a doctor may build over two sessions.
Guide
Mapping the depression before choosing a technique
Not every forehead dip is the same. In a 2018 report in Plastic and Reconstructive Surgery Global Open, Kim sorted forehead depressions into five categories by severity, shape, contour, slope and volume deficit. A tumescent fluid was injected first to open a space above the bone, then calcium hydroxylapatite went in through one central entry point. Across 218 patients, the author reported no vascular problems, irregularity, infection or prolonged swelling.
For a patient, the useful part is the logic. Ask the doctor to describe your forehead in plain words, because a clear description usually leads to a clearer dose.
- Where the hollow sits: center, sides, or near the hairline
- Whether the brow ridge already projects
- How many entry points the plan uses, and where
Guide
Cannula, needle and the arteries that reach the eye
The supraorbital and supratrochlear arteries rise from the eye socket into the forehead and branch from the artery that feeds the retina. Gel that enters one and travels backward can block blood flow to the eye. Kim's report names skin necrosis and blindness as reasons many physicians avoid forehead filler. The event is rare, but real.
A blunt cannula pushes vessels aside more easily than a sharp needle and covers a wide area from few entry points. A needle placed straight down onto bone, as in the Rauso series, gives exact placement at depth. Neither removes the risk; slow, low-pressure injection in a deep plane, small amounts per pass and knowledge of vessel paths lower it.
Guide
Fitting forehead treatment into a stay around Hongdae
Book the injection early in the trip rather than the day before departure, so a review is possible if one side looks uneven. Swelling can settle onto the upper eyelids for several days, so leave a margin before photos. Bring a list of earlier forehead gel, fat grafting or threads, and any blood thinners.
Clinics in the area usually quote forehead work by the cc or syringe, before VAT, with 10% VAT added at payment. Ask for the planned amount in writing beforehand.
Evidence
Research behind this page
- Long-term Stability and Hyaluronic Acid Filler Selection for Forehead ContouringJournal of Craniofacial Surgery · 2025 · doi:10.1097/scs.0000000000011652
Retrospective series of 38 patients given a low-elasticity monophasic hyaluronic acid gel above the frontal bone, with a mean 16 mL dose, no reported complications and stable contour up to 36 months.
- Novel Forehead Augmentation Strategy: Forehead Depression Categorization and Calcium-Hydroxyapatite Filler Delivery after Tumescent InjectionPlastic and Reconstructive Surgery - Global Open · 2018 · doi:10.1097/gox.0000000000001858
Described a five-category forehead depression system and calcium hydroxylapatite delivery after tumescent hydrodissection through one central entry, reporting no vascular events in 218 patients.
FAQ
Questions about Fillers in Hongdae
Can forehead filler cause blindness?
Yes, vision loss after facial filler has been reported, and the forehead is one of the zones where it can happen. The arteries above the brows connect to the artery that supplies the retina, so gel pushed into one of them can travel toward the eye. It is rare. Sudden eye pain, blurred sight or skin blanching during injection means the procedure should stop and emergency treatment begin at once, before you leave the room.
Does hyaluronidase work if the forehead was treated with Radiesse?
No, hyaluronidase dissolves hyaluronic acid only and has no effect on calcium hydroxylapatite. That is the main reason some doctors keep hyaluronic acid for a first forehead treatment. If Radiesse or another non-hyaluronic product was placed in your forehead before, say so at consultation, because it changes the plan and the options for later correction. Keep the product name in writing.
Will a forehead injection also smooth my horizontal lines?
Only partly, and often not at all. Horizontal lines that deepen when you raise your brows come from the frontalis muscle, which gel does not relax. Filler changes the curve of the bone surface; botulinum toxin is the usual and more direct tool for muscle-driven lines. Some plans combine the two, with toxin first and contour work after it has settled.
How long do forehead results usually last?
It depends on the product and the person, and results vary from person to person. In the Rauso series published in 2025, contour held up to 36 months with a soft hyaluronic acid gel placed on bone, which is longer than many people expect for that material. That was one retrospective group, mostly men, so treat it as a reported outcome rather than a promise, and ask the doctor what they see with the product they use.
Can I wear a hat or work out after forehead filler?
Most doctors ask you to avoid pressure on the forehead and heavy exercise for a day or two. A tight cap, helmet or goggle strap can shift fresh gel or press on swollen tissue. Sleep with the head slightly raised the first night and skip saunas and alcohol briefly. Follow the clinic's written aftercare, since advice differs a little by product.
Who should postpone forehead filler?
Pregnant or breastfeeding people, anyone with an active skin infection or cold sore near the area, and anyone with an autoimmune flare are usually asked to wait. A history of forehead implants, permanent fillers or recent surgery also needs a careful review first. If you take blood thinners, do not stop them on your own; tell the doctor, who will judge the bruising risk with your prescriber.