Guide · Hyaluronidase
Hyaluronidase side effects: what is normal, what is rare, and what needs help
The enzyme used to dissolve hyaluronic acid filler is generally well tolerated, but it is a medicine with real side effects. This guide separates the expected from the uncommon, explains the allergy question honestly and lists the signs that should not wait.
Written & medically reviewed by Dr Sin Yong · 9 October 2026
Quick answer
- Common hyaluronidase side effects are swelling, redness, itch, tenderness and small needle marks for a day or two, and sometimes bruising. These are expected and usually settle without treatment.
- Allergy is uncommon but possible because the enzyme is a protein. Reported reactions after dissolving filler are mainly localised swelling appearing an hour or more later; severe reactions are rare. Untreated bee or wasp sting allergy raises the risk and needs specialist review first.
- Dissolving can leave an area flatter or more hollow than wanted, either briefly while swelling settles and native hyaluronic acid recovers, or longer if more filler is removed than intended. Precise, staged treatment lowers this risk.
- Hyaluronidase is a prescription medicine given by a doctor after assessment. At SkinRev Lab and IN Eternity Clinic it is given by Dr Sin Yong, and treatment is priced at consultation.
Background
Why hyaluronidase has side effects at all
Hyaluronidase breaks down hyaluronic acid (HA). In aesthetic medicine it is used to dissolve HA filler that is lumpy, misplaced, excessive or causing a problem, and urgently when filler blocks a blood vessel. Medical preparations are made from animal sources or by recombinant technology, and they differ in purity and in what they are mixed with.
Side effects come from three places. The injections themselves cause needle trauma, swelling and sometimes bruising. The enzyme acts on your own natural HA as well as the filler, briefly changing the feel and fullness of the area. And because the enzyme is a protein, the immune system can occasionally react to it, or to preservatives or impurities in some formulations.
Expected
Common hyaluronidase side effects
A UK guideline describes a non-allergic injection-site reaction, with redness and some swelling that subsides within about 24 hours, which can occur especially with higher doses. It is a predictable effect of the medicine rather than an allergy, and allergy skin tests in these people are normal.
Avoiding massage, strenuous exercise and saunas for about a day helps the common effects settle. Results vary between people, and the result is judged at review rather than in the first few days.
| Effect | How common | Typical course |
|---|---|---|
| Swelling at injection sites | Common | Usually a day or two; can be longer after larger treatments |
| Redness and warmth | Common | Often settles within about 24 hours |
| Itch | Common | Usually brief; increasing or spreading itch should be reported |
| Tenderness or stinging | Common | Mainly during and shortly after the injections |
| Bruising | Sometimes | Usually fades over one to two weeks, as with other facial injections |
| Temporary flatter or hollow look | Sometimes | Often improves over days as swelling settles and native HA is restored |
Allergy
Hyaluronidase allergy: how likely, and what it looks like
In settings where hyaluronidase has been used for decades, such as eye surgery, reported allergy rates in published series range from well under one in a thousand to under one in a hundred, and the UK guideline notes that only four allergic reactions needing adrenaline have been reported since 1949. In aesthetic medicine, published reports of allergy after dissolving filler are few, though the guideline's authors believe it is under-reported.
Two types matter. Immediate reactions start within minutes to an hour and can include hives, itch, flushing and swelling; rarely, they involve breathing or circulation. Delayed reactions start an hour or more later and usually appear as firm, itchy, red swelling around the injected area. The guideline notes that reported reactions after local injection are mainly of the delayed, localised kind.
The guideline also notes that allergy was almost always linked to previous exposure to hyaluronidase or to bee or wasp venom. Some reactions may also relate to preservatives or protein impurities in some formulations rather than the enzyme itself, which is one reason the doctor records which preparation is used.
Stings
Bee and wasp sting allergy and hyaluronidase
Bee and wasp venoms contain their own hyaluronidase, which is similar enough to the medical enzyme to cause cross-reactions in some people. In a 2024 study from Munich, 90 people with confirmed allergic reactions to stings had skin-prick tests to medical hyaluronidase. None of those who had completed venom immunotherapy, and none of the bee-allergic group, tested positive; but 5 of 23 wasp-allergic people who had never had immunotherapy did. None of 30 healthy controls reacted.
The authors concluded that people with an untreated sting allergy, particularly to wasps, are probably at the highest risk and should see an allergy specialist before hyaluronidase is used. If you have ever had a significant reaction to a sting, say so at consultation, even if it was years ago.
Testing
What a skin test can and cannot tell you
Many clinics inject a tiny amount of hyaluronidase into the skin of the forearm and watch for a reaction before treatment. A positive result is useful information. A negative result is reassuring, but it is not proof: a review in Archives of Plastic Surgery notes that delayed allergic reactions may not be predicted by skin tests.
Allergy societies also caution against using skin tests to screen people without a relevant history, as the UK guideline points out. In practice, your history guides the approach. Someone with no allergy history may proceed with standard precautions; someone with a strong sting reaction or a previous reaction to hyaluronidase may need a specialist allergy assessment, or a plan that avoids the enzyme.
Over-correction
Over-dissolving, hollowing and loose-looking skin
Hyaluronidase does not distinguish neatly between filler you want to lose and filler you want to keep, and it briefly reduces your own natural HA too. The UK guideline notes that the body restores native HA within about 15 to 20 hours, so a flatter look in the first days is often temporary. A lasting hollow is more likely when more filler is dissolved than was needed, or when filler had been masking volume loss underneath.
Where a large amount of filler had stretched the skin over years, the area can look a little looser once the volume is gone. This is not the enzyme damaging tissue; it reveals what was beneath. Ultrasound mapping, placing small amounts directly into the problem deposit and treating in stages with a review in between all help reduce over-correction. Different gels dissolve at different rates, which is another reason to go step by step.
If an area does look too flat once everything has settled, options include waiting, energy-based skin treatments, a collagen biostimulator or, after an appropriate gap, a small amount of filler placed in the right layer. None of these should be rushed in the first weeks.
Rare
Rare reactions and what else can look like a side effect
Rare reactions include a serious immediate allergic reaction, extensive swelling, or an infection at an injection site, as with any injection. In five small randomised trials reviewed in 2024, in which hyaluronidase was used on HA nodules in the skin of the arm or back, no major adverse reactions were reported, but those trials were small and did not involve the face.
Not everything that happens after dissolving is caused by the enzyme. A lump that becomes red, firm or tender weeks or months later may be a delayed inflammatory reaction to remaining filler. A 2026 meta-analysis estimated these occur in about one in 2,000 people per year of follow-up, with a median onset of three months after filler; they are assessed and treated in their own right. Swelling that comes and goes with salt, sleep or hormones may be fluid rather than filler.
Who should not
Who should not have hyaluronidase, or needs extra care
Emergency use is different. When filler has blocked a blood vessel, delay causes harm, and the balance of risk usually favours prompt treatment with appropriate precautions. This is a decision for the treating doctor in the moment.
If your concern is outside what dissolving can fix, such as a non-HA filler that may need removal, a growth that needs a diagnosis, or a skin condition, you should be referred to a plastic surgeon or dermatologist as appropriate.
- Previous allergic reaction to hyaluronidase.
- Untreated bee or wasp sting allergy, especially wasps: allergy specialist review first.
- Pregnancy: elective dissolving is not advised.
- Infection or broken skin in the area to be treated.
- Filler that is not hyaluronic acid, where the enzyme offers no benefit.
- Uncertain expectations: if the goal is unclear, a review and photographs before treatment help.
Red flags
What to watch for after hyaluronidase
Mild swelling, a little redness and a slightly uneven look in the first day or two are expected. What matters is the direction of travel: things that are settling are usually fine; things that are getting worse should be checked.
If you are unsure whether something is normal, contact the clinic rather than waiting it out. A clear photograph taken in good light, a note of when the change started and a list of anything you have taken for it help whoever reviews you, and tell any doctor you see that you have had hyaluronidase and when.
- Within minutes to an hour: widespread hives, swelling of the lips, tongue or throat, wheeze, breathing difficulty or feeling faint. Call 995 or go to an emergency department.
- Hours to two days: swelling, redness or itch that keeps increasing or spreads beyond the treated area. Contact the clinic the same day.
- Any time: skin turning pale, white, blotchy or dusky, pain that is increasing, or any change in vision. Seek help immediately.
- Days later: fever, increasing heat, pus or a hot, tender lump. Contact the clinic for review.
- Weeks later: a new lump or recurring swelling. Book a review rather than waiting.
At SkinRev Lab
How Dr Sin Yong plans hyaluronidase treatment
At SkinRev Lab, #B1-28 CityLink Mall (City Hall and Esplanade MRT, open daily 11am to 8pm), and at IN Eternity Clinic, Pacific Plaza, Orchard, hyaluronidase is given only by Dr Sin Yong after a consultation. He asks about previous filler and dissolving, allergies including stings, medicines and pregnancy, examines the area and, where useful, images it with ultrasound before deciding anything.
He then sets out the options: dissolving all or part of the filler, doing it in stages, a plan that does not use the enzyme, referral to an allergy specialist, plastic surgeon or dermatologist, or no treatment. Side effects and aftercare are explained before you decide. Treatment is priced at consultation; WhatsApp SkinRev Lab on +65 8266 9585 to book.
Sources
References & sources
- Murray G, Convery C, Walker L, Davies E. Guideline for the safe use of hyaluronidase in aesthetic medicine, including modified high-dose protocol. J Clin Aesthet Dermatol. 2021;14(8):E69-E75.
- Jung H. Hyaluronidase: an overview of its properties, applications, and side effects. Arch Plast Surg. 2020;47(4):297-300.
- Bertlich M, Hartmann D, Freytag S, French LE, Oppel E. Sensitization against medical hyaluronidase in patients with confirmed hypersensitivity against hymenoptera species and its clinical implications. Br J Dermatol. 2024;191(6):1000-1007.
- Borzabadi-Farahani A, Mosahebi A, Zargaran D. A scoping review of hyaluronidase use in managing the complications of aesthetic interventions. Aesthetic Plast Surg. 2024;48(6):1193-1209.
- Landau M. Hyaluronidase caveats in treating filler complications. Dermatol Surg. 2015;41 Suppl 1:S347-S353.
- Hong GW, Hu H, Wan J, et al. How should we use hyaluronidase for dissolving hyaluronic acid fillers? J Cosmet Dermatol. 2025;24(1):e16783.
- Seo J, Kadouch J, Pavicic T, et al. Incidence and characteristics of delayed inflammatory reactions secondary to hyaluronic acid filler injections: a systematic review with meta-analysis. Aesthet Surg J Open Forum. 2026;8:ojag165.
Common questions
Your questions,
answered
What are the side effects of hyaluronidase?
Commonly swelling, redness, itch, tenderness and small needle marks for a day or two, and sometimes bruising. Less commonly, allergy, over-dissolving or a hollow look. Serious reactions are rare.
How long does swelling last after hyaluronidase?
Usually a day or two. After larger treatments it can last a little longer. Swelling that keeps increasing after the first day should be checked.
How common is hyaluronidase allergy?
Uncommon. In eye surgery series, rates range from well under one in a thousand to under one in a hundred, and few cases have been reported after dissolving filler, though they may be under-reported.
Can hyaluronidase dissolve my natural hyaluronic acid?
It breaks down some native HA in the treated area, but the body restores it within about 15 to 20 hours, according to a UK guideline.
Can hyaluronidase make my face look hollow?
It can, briefly, as swelling settles. A lasting hollow is more likely if more filler is removed than needed or if filler was hiding volume loss. Precise, staged treatment reduces the risk.
I am allergic to bee stings. Can I have hyaluronidase?
Tell your doctor. People with an untreated sting allergy, particularly to wasps, are advised to see an allergy specialist first. Those who have completed venom immunotherapy appeared less likely to react in one study.
Does a negative skin test mean I cannot react?
No. It is reassuring but does not rule out delayed reactions, which may not show on a skin test.
Can I have hyaluronidase while pregnant?
Elective dissolving is not advised during pregnancy. Non-urgent correction can wait until after pregnancy.
What should I do if my face swells the next day?
Mild swelling is expected. Swelling, redness or itch that keeps increasing or spreads should be reported to the clinic the same day. Breathing difficulty or throat swelling is an emergency: call 995.