Dermal filler swelling: causes, diagnosis and management, a 2026 update

By Dr Andy Taylor · Published 3 November 2026 · Last reviewed 3 November 2026

Treatment at our clinic: Ultrasound-guided fillers

Some swelling after dermal filler is normal. It happens with every type of filler and usually settles within about a week.^1,2 Less often, swelling is a sign of a problem such as an allergic reaction, an infection, a delayed inflammatory reaction or, rarely, a blocked blood vessel. This guide explains how to tell the difference and when to get help.

Key points

• Swelling and bruising are the most common reactions to filler. Most swelling caused by the injection itself settles within a week.¹
• Swelling that comes on suddenly with severe pain, pale or mottled skin, or any change in your vision needs urgent help.³
• Swelling can also start weeks or months later, sometimes after an illness, an infection or dental work.^4,5
• Abnormal swelling is assessed with a history, an examination and sometimes ultrasound, and treatment depends on the cause.^3,4
• Much of the guidance on filler complications comes from expert agreement and case reports, not from large trials.^2,4

Why does filler cause swelling?

There are two main reasons. First, the needle or cannula causes a small injury to the tissue, and the body responds with swelling and sometimes bruising.¹ Second, most fillers are made of hyaluronic acid, which draws in water. More concentrated products, or those with larger particles, tend to absorb more water and cause more swelling after injection.¹

How long does normal swelling last?

Most swelling caused by the injection settles within one week.¹ Some swelling straight after treatment is normal with all fillers.² At our clinic, we tell patients to expect swelling and possible bruising for 2 to 7 days. Swelling, bruising, tenderness and small lumps are common and usually settle within two weeks, and swelling can hide the result for up to two weeks. This is why your review appointment is about two weeks after treatment.

What can I do about normal swelling?

The advice in the published reviews is simple.¹

• Use a cold compress after treatment. This is the advice given for bruising.
• Keep your head raised for the first 24 hours.
• Avoid vigorous exercise for the first 24 hours, because raising your blood pressure can make bruising worse.

You will be given written aftercare after your treatment. Follow it, and contact the clinic if you are unsure about anything.

What about swelling under the eyes?

Swelling below the eyes after filler in the cheek or tear trough area is called malar oedema. It has been reported with all types of filler.² It is thought to be related to how much filler is used and how deep it is placed.¹ Unlike normal post-injection swelling, it can last a long time and can be hard to treat.²

Early measures described in one review include keeping the head raised, cold compresses and gentle pressure on the area.¹ Swelling under the eyes that persists should be assessed by the person who treated you.

When is swelling a sign of something more serious?

Allergic reactions

A sudden allergic swelling, called angioedema, usually starts within hours of treatment. It can be severe and can last several weeks.^1,2 A slower type of reaction, with firm, red, swollen skin, usually appears about a day after treatment but can appear several weeks later.^1,2

Infection

Infection can follow any procedure that breaks the skin. Late infections generally develop two or more weeks after treatment.² Some late reactions are thought to involve a biofilm, a layer of bacteria that sits on the filler and is hard to detect with standard tests.² A red, hard area appearing at any time after treatment should be checked.¹

Delayed inflammatory reactions

Some people develop swelling, redness, tender lumps or firm areas weeks or months after an uneventful treatment. One expert panel describes these as delayed inflammatory reactions, arising two to four weeks or more after injection.⁴ Possible triggers include viral infections, sinus infections and dental procedures. Small, short-lived swollen lumps are often seen during or after a brief illness.⁴

A 2025 systematic review found similar reactions reported after viral infections and vaccinations, starting from a few hours to several weeks after the illness or vaccine.⁵ The evidence is weak. The review included only six small case series and case reports, covering 25 women, so it cannot tell us how common these reactions are or whether vaccination causes them.⁵

Blocked blood vessel (vascular occlusion)

This is the most serious complication and it is rare.⁶ It happens when filler enters or presses on an artery and blocks blood flow. The main warning signs are pain and a change in skin colour.² The pain is often severe and out of proportion to the treatment.^2,3 The skin may turn pale at first, then develop a purple, net-like mottled pattern or a dusky appearance.³ These changes usually happen straight away or within a few hours, but can occasionally be delayed.³

Any change in your vision after filler is an emergency. A blocked vessel can, very rarely, affect the eye.^3,7

What are the red-flag signs?

Contact the clinic straight away on 07798 765623, at any time, if you notice:

• pain that is severe, getting worse, or out of proportion to the treatment^2,3
• skin that is pale, blotchy, purple, mottled or dusky in or near the treated area³
• swelling that is getting worse rather than better, especially with redness and heat^1,2
• a red, hard or tender area appearing days, weeks or months after treatment^1,4
• swelling of the lips, tongue or throat, or any difficulty breathing¹

If you cannot reach the clinic, go to your nearest A&E. If you have any change in your vision, or difficulty breathing, call 999 or go to A&E at once.

How is abnormal swelling assessed?

Assessment starts with your history: when the swelling started, whether it is painful, whether you have been unwell, and what was injected and where. This is followed by an examination of the area, including skin colour and how quickly colour returns after gentle pressure.³

Ultrasound can show where filler sits in the tissues.⁸ One expert panel notes that several publications regard ultrasound as the best test for delayed reactions, because it can locate lumps and show the filler.⁴ In a blocked vessel, small published series show that a scan helps the injector find the filler and the affected vessel, and treat it in a targeted way.⁹ Before and during treatment, I scan the area with ultrasound, and the same scan can be used if a problem is suspected.

How is abnormal swelling treated?

Abnormal swelling needs assessment and treatment by the injector or a doctor, following a written complications plan. Expert guidance stresses having clear plans and referral routes in place before any problem arises.³ Our clinic follows a written plan for managing complications.

Treatment depends on the cause. For a blocked blood vessel caused by hyaluronic acid filler, the main treatment is hyaluronidase, a medicine that dissolves hyaluronic acid filler, given as early as possible.³ Hyaluronidase is also used in some cases of persistent lumps or swelling under the eyes after hyaluronic acid filler.² It should not be used while an infection is active.² Infections and inflammatory reactions may also need medicines a doctor may prescribe.

Most of this guidance is based on expert consensus and clinical experience. One major consensus paper rates its own evidence at the lowest level, drawn mainly from case reports and practitioners’ experience.²

Frequently asked questions

Is swelling after filler normal?

Yes. Some swelling happens with all fillers and most settles within a week.^1,2 At our clinic we advise allowing 2 to 7 days for swelling and possible bruising.

Why are my lips more swollen on one side?

Swelling is most common in the lips and around the eyes, and it can be uneven in the first few days.² If one side is painful, pale or mottled, contact the clinic straight away.³ Otherwise, wait for your two-week review before judging the result.

Can filler swell months after treatment?

Yes. Delayed inflammatory reactions can appear weeks or months later, sometimes after an illness, an infection or dental work.^4,5 Contact the person who treated you if this happens.

Can vaccines trigger filler reactions?

The reports of filler reactions after vaccination are small case series and case reports. They do not show how common these reactions are.⁵ Discuss any concerns with your GP or the person who treated you.

Can ultrasound tell whether swelling is normal?

Ultrasound shows where filler sits, and experts use it to assess lumps and late reactions.^4,8 It adds to, but does not replace, a proper history and examination.

Sources

1. Funt D, Pavicic T. Dermal fillers in aesthetics: an overview of adverse events and treatment approaches. Clinical, Cosmetic and Investigational Dermatology 2013;6:295-316.
2. Urdiales-Gálvez F et al. Treatment of soft tissue filler complications: expert consensus recommendations. Aesthetic Plastic Surgery 2018;42(2):498-510.
3. Murray G, Convery C, Walker L, Davies E. Guideline for the management of hyaluronic acid filler-induced vascular occlusion. Journal of Clinical and Aesthetic Dermatology 2021;14(5):E61-E69.
4. Artzi O et al. Delayed inflammatory reactions to hyaluronic acid fillers: a literature review and proposed treatment algorithm. Clinical, Cosmetic and Investigational Dermatology 2020;13:371-378.
5. Bhatia L et al. Systematic review of post-viral delayed inflammation associated with hyaluronic acid dermal fillers. Medicina (Kaunas) 2025;61(10):1764.
6. Alam M et al. Rates of vascular occlusion associated with using needles vs cannulas for filler injection. JAMA Dermatology 2021;157(2):174-180.
7. Beleznay K et al. Update on avoiding and treating blindness from fillers: a recent review of the world literature. Aesthetic Surgery Journal 2019;39(6):662-674.
8. Schelke LW, Decates TS, Velthuis PJ. Ultrasound to improve the safety of hyaluronic acid filler treatments. Journal of Cosmetic Dermatology 2018;17(6):1019-1024.
9. Schelke LW et al. Ultrasound-guided targeted vs regional flooding: a comparative study for improving the clinical outcome in soft tissue filler vascular adverse event management. Aesthetic Surgery Journal 2023;43(1):86-96.