Procedure guide
How hyaluronic acid fillers restore volume, how long they last, and how risks are managed.
Written by Orr Shauly, MD, plastic surgery resident. Updated .
For information and education only, not medical advice.
The short answer.
Hyaluronic acid fillers are injectable gels of a molecule found naturally in the body, used to restore lost volume, soften folds and enhance the lips, cheeks and under-eye hollows.1,2 Results typically last about 6 - 18 months depending on the product and area, and hyaluronic acid can be dissolved with an enzyme called hyaluronidase if needed.2-4 Most side effects are short-lived swelling and bruising, while blocking a blood vessel is rare, about 1 per 6,410 syringes with needles and 1 per 40,882 with cannulas in a large study, but can cause skin loss or vision loss.5,6
- 1.7 Million Syringes
- occlusion study
- Filler syringes reported by 370 dermatologists, with vascular occlusion in fewer than 1 per 5,000 for any product and technique.6
- 85%
- occlusions without sequelae
- Vascular occlusion events that resolved without lasting injury in the same study.6
- 59%
- still improved at 18 months
- Nasolabial folds still improved 18 months after treatment with one long-lasting hyaluronic acid filler.3
- 6 Hours
- treatment window
- Hyaluronidase given within about 6 hours of a vascular complication was associated with better outcomes.7
What hyaluronic acid fillers are.
Fillers are injected to restore volume lost with aging, smooth folds and creases and enhance features such as the lips and chin. Each product has its own physical properties, risks and ideal injection depth.1 Hyaluronic acid fillers are temporary and can be dissolved, unlike semipermanent options such as calcium hydroxyapatite and poly-L-lactic acid or permanent fillers.2
Fillers treat volume loss and lines at rest, while neuromodulators relax muscles that create lines with movement. The two are often combined.2
What fillers are used for.
| Area | Typical Goal | Evidence |
|---|---|---|
| Nasolabial Folds3,8 | Soften the folds from nose to mouth | Effective in 18 randomized trials of 2,521 patients |
| Lips9 | Add fullness and definition | Response rates of 71% - 93.2% across 22 studies of 3,965 patients |
| Cheeks, Midface10 | Restore volume lost with age | 79.0% of patients rated cheeks improved at 2 years with one volumizing filler |
| Tear Trough4 | Soften hollows under the eyes | High satisfaction, with effects lasting 8 - 12 months |
Some areas carry more risk. Forehead and glabellar lines require superficial placement near important vessels, and the thin skin under the eyes requires deep, conservative placement.2
Who is a candidate.
Candidates want to restore or enhance volume without surgery and understand that results are temporary. A history of reactions to a specific filler, active skin infection at the site and recent laser or peel treatments are reasons to wait or avoid treatment.2 People with a history of cold sores may receive antiviral medication before lip or perioral treatment.2
Autoimmune disease, recent dental work and viral infections may increase the risk of delayed reactions, according to a consensus of experts.11
How a filler treatment works.
- Assessment: The face is examined for volume loss, skin thickness, asymmetry and veins that could cause bruising.2
- Comfort: Topical or local anesthesia is used, and many products contain lidocaine.2,4
- Injection: Filler is placed with a fine needle or a blunt cannula at the depth suited to the area. In a large study, cannulas had 77.1% lower odds of vascular occlusion than needles.1,6
- Shaping: The result is shaped before the patient leaves, so home massage is rarely needed.2
Experience matters. Injectors with more than 5 years of experience had 70.7% lower odds of causing a vascular occlusion.6 Plastic surgeons who inject hyaluronic acid are advised to keep hyaluronidase on hand and have a plan for complications.12
What to expect afterward.
Fillers are often described as having no downtime, but swelling and bruising are common for several days.2
| Time | What Usually Happens |
|---|---|
| First 24 Hours2 | Intermittent cooling limits swelling |
| Days 3 - 72 | Swelling settles, and strenuous activity is limited |
| Weeks 1 - 22 | Bruising fades, or up to 3 weeks if a larger vein was punctured |
| Months 6 - 183,4,10 | Effects gradually fade, at different rates by product and area |
Side effects and safety.
In a review of 48 randomized trials, most side effects were short-lived injection site reactions, such as swelling, tenderness, firmness and bruising, that resolved without treatment within weeks.5 Lumps, overcorrection and asymmetry can usually be corrected by massage, additional filler or dissolving with hyaluronidase.2
| Risk | Reported Rate | Context |
|---|---|---|
| Vascular Occlusion, Needle6 | 1 / 6,410 | Per 1 mL syringe, most without lasting injury |
| Vascular Occlusion, Cannula6 | 1 / 40,882 | Per 1 mL syringe |
| Early Complications13 | 29 / 41,775 | Cases in a multicenter study, most often vascular compromise |
| Late-Onset Reactions11 | Rare | Swelling or nodules weeks to months later |
| Bluish Discoloration2 | NR | Tyndall effect from filler placed too superficially |
Vascular occlusion happens when filler enters or compresses an artery. It can cause skin to die, and rarely, in the nose, glabella and forehead, it can block the artery to the eye and cause permanent vision loss, even with volumes as small as 0.2 mL.14,15 Nasolabial folds and lips had the most occlusions, while the glabella had the most severe ones.6
Prompt treatment with hyaluronidase dissolves the filler. In a meta-analysis of 231 patients with vascular complications, skin necrosis resolved in 78.4% and visual impairment in 45.2%, with better outcomes when treated within about 6 hours.7 Injecting hyaluronidase behind the eye for filler-related blindness has not been shown to reliably restore vision.16
Results and how long they last.
Duration depends on the product and area. In one randomized nasolabial fold study, 93% of folds were improved at 6 months and 59% at 18 months, and a repeat treatment needed about one-third of the original volume.3 In the midface, patients reported looking about 5 years younger at 6 months and 3 years younger at 2 years.10
Alternatives.
Fat grafting uses a person's own fat for longer-lasting volume but requires liposuction. Semipermanent fillers such as calcium hydroxyapatite and poly-L-lactic acid can last up to about 1 - 2 years but cannot be dissolved with hyaluronidase.1,2 Surgery such as a facelift or eyelid surgery treats sagging and excess skin that fillers cannot.1
What we don't know yet.
- True Complication Rates: Severe events are rare enough that rates come from surveys and case collections.6,14
- Treating Vision Loss: No treatment has been proven to reverse filler-related blindness.15,16
- Hyaluronidase Dosing: The best dose and protocol for complications are not standardized.7,12
- Late Reactions: The causes of delayed reactions are still debated.11
Common questions.
How long do lip fillers last?
It varies by product, volume and person. Studies of hyaluronic acid lip fillers report effects lasting many months, fading gradually as the body breaks down the filler.
Can fillers be dissolved?
Yes. Hyaluronic acid fillers can be dissolved with an enzyme called hyaluronidase, which is used for overcorrection, lumps and vascular complications.
Are fillers safe?
Most side effects are mild swelling and bruising. The rare serious risk is filler blocking a blood vessel, which can cause skin loss or, very rarely, vision loss, so injector training and anatomical knowledge are essential.
What are the warning signs of a filler complication?
Any change in vision or in the color of the skin after an injection needs immediate evaluation. Vision problems from filler appear almost immediately, and treatment with hyaluronidase works best when given early.
What is the difference between filler and Botox?
Fillers add volume to fill folds and hollows, while neuromodulators such as Botox relax the muscles that cause lines with movement. They are often used together.
Is there downtime after fillers?
Swelling usually settles within 3 - 5 days and bruising within 1 - 2 weeks, so treatment shortly before an important event is best avoided.
Are fillers right for me?
Only an in-person evaluation can answer that. This guide is educational and cannot assess an individual case. A qualified plastic surgeon or dermatologist can review your goals, anatomy and health history with you.
Key terms.
- Hyaluronic Acid
- A molecule naturally found in connective tissue, used as a temporary injectable filler.
- Dermal Filler
- An injectable gel used to restore volume or smooth lines.
- Hyaluronidase
- An enzyme that dissolves hyaluronic acid filler.
- Vascular Occlusion
- Blockage of a blood vessel by filler, which can damage skin or, rarely, the eye.
- Cannula
- A blunt-tipped injection tube that lowers the risk of entering a blood vessel.
- Tyndall Effect
- A bluish discoloration when hyaluronic acid filler is placed too close to the skin surface.
- Tear Trough
- The hollow groove running from the inner corner of the eye toward the cheek.
- Calcium Hydroxyapatite
- A semipermanent filler made of mineral microspheres that cannot be dissolved.
- Poly-L-Lactic Acid
- A semipermanent injectable filler that may last up to about 2 years.
References.
- 1.Pestana IA, Marks MW. Dermal and soft-tissue fillers: principles, materials, and techniques. In: Chung KC, editor. Grabb and Smith's plastic surgery. 8th ed. Philadelphia: Wolters Kluwer; 2020. p. 472-80.
- 2.Ghavami A, Graivier M. Soft tissue fillers. In: Janis JE, editor. Essentials of aesthetic surgery. New York: Thieme; 2018. p. 280-96.
- 3.Dayan S, Maas CS, Grimes PE, Beer K, Monheit G, Snow S, et al. Safety and Effectiveness of VYC-17.5L for Long-Term Correction of Nasolabial Folds. Aesthet Surg J. 2020;40(7):767-77. PubMed
- 4.Trinh LN, Grond SE, Gupta A. Dermal Fillers for Tear Trough Rejuvenation: A Systematic Review. Facial Plast Surg. 2022;38(3):228-39. PubMed
- 5.Kyriazidis I, Spyropoulou GA, Zambacos G, Tagka A, Rakhorst HA, Gasteratos K, et al. Adverse Events Associated with Hyaluronic Acid Filler Injection for Non-surgical Facial Aesthetics: A Systematic Review of High Level of Evidence Studies. Aesthetic Plast Surg. 2024;48(4):719-41. PubMed
- 6.Alam M, Kakar R, Dover JS, Harikumar V, Kang BY, Wan HT, et al. Rates of Vascular Occlusion Associated With Using Needles vs Cannulas for Filler Injection. JAMA Dermatol. 2021;157(2):174-80. PubMed
- 7.Alhusain AM, Alsaif M, Alkhathami AM, Alghamdi AM, Alkhunein J, Alqirnas M, et al. Hyaluronidase Protocol in Management of Hyaluronic Acid Filler-Related Vascular Complications: A Systematic Review and Meta-Analysis. Aesthetic Plast Surg. 2026;50(6):2300-17. PubMed
- 8.Huang X, Liang Y, Li Q. Safety and efficacy of hyaluronic acid for the correction of nasolabial folds: a meta-analysis. Eur J Dermatol. 2013;23(5):592-9. PubMed
- 9.Stojanovič L, Majdič N. Effectiveness and safety of hyaluronic acid fillers used to enhance overall lip fullness: A systematic review of clinical studies. J Cosmet Dermatol. 2019;18(2):436-43. PubMed
- 10.Few J, Cox SE, Paradkar-Mitragotri D, Murphy DK. A Multicenter, Single-Blind Randomized, Controlled Study of a Volumizing Hyaluronic Acid Filler for Midface Volume Deficit: Patient-Reported Outcomes at 2 Years. Aesthet Surg J. 2015;35(5):589-99. PubMed
- 11.Baranska-Rybak W, Lajo-Plaza JV, Walker L, Alizadeh N. Late-Onset Reactions after Hyaluronic Acid Dermal Fillers: A Consensus Recommendation on Etiology, Prevention and Management. Dermatol Ther (Heidelb). 2024;14(7):1767-85. PubMed
- 12.Olaiya OR, Forbes D, Humphrey S, Beleznay K, Mosher M, Carruthers J. Hyaluronidase for Treating Complications Related to HA Fillers: A National Plastic Surgeon Survey. Plast Surg (Oakv). 2022;30(3):233-7. PubMed
- 13.Nishikawa A, Aikawa Y, Kono T. Current Status of Early Complications Caused by Hyaluronic Acid Fillers: Insights From a Descriptive, Observational Study of 41,775 Cases. Aesthet Surg J. 2023;43(8):893-904. PubMed
- 14.Rentfro K, Clarey D, Glenn EJ, Sulewski R, Wysong A. Soft Tissue Dermal Filler-Associated Necrosis and Impending Necrosis: A Systematic Review of the Literature. Dermatol Surg. 2022;48(10):1051-6. PubMed
- 15.Kapoor KM, Kapoor P, Heydenrych I, Bertossi D. Vision Loss Associated with Hyaluronic Acid Fillers: A Systematic Review of Literature. Aesthetic Plast Surg. 2020;44(3):929-44. PubMed
- 16.Paap MK, Milman T, Ugradar S, Goldberg R, Silkiss RZ. Examining the Role of Retrobulbar Hyaluronidase in Reversing Filler-Induced Blindness: A Systematic Review. Ophthalmic Plast Reconstr Surg. 2020;36(3):231-8. PubMed