Hyaluronidase Side Effects: Allergy, Swelling and What to Expect
Hyaluronidase is the enzyme used to dissolve hyaluronic acid filler. Medical Director Dr Sin Yong sets out its side effects, how often allergy is reported, who should have a skin test first, and what it does and does not do to your own tissue.
Treatment page: dissolve filler and filler correction in Singapore.
WhatsApp to Enquire →Key facts ↓The common side effects of hyaluronidase are swelling, redness, bruising and tenderness at the injection site, which settle within a few days. Allergic reactions are uncommon: published reports put the rate at 0.05% to 0.69%, with hives or facial swelling in under 0.1%. People with a bee sting allergy, or a past reaction to the enzyme, need a skin test or a different plan. The enzyme also breaks down some of your own hyaluronic acid, which the body replaces.
- Common and short-lived: swelling, redness, bruising, stinging and tenderness where the enzyme is injected, usually settling in two to three days.
- Allergy is uncommon: reported in 0.05% to 0.69% of people, with hives or angioedema in under 0.1% [1].
- Bee sting allergy matters: cross-reactions can occur in people allergic to bee stings or to bovine collagen, so tell the doctor beforehand [1].
- A skin test can be done first: a small test dose is placed in the skin and watched. It does not rule out a delayed reaction, which can appear after 24 hours [1].
- The enzyme is short-lived: it is inactivated in tissue within a short time, although the filler continues to soften over the next day or two [1].
Common side effects
- Swelling. The area can look puffier for one to three days, partly from the injected fluid.
- Bruising and redness, as with any injection.
- Stinging during the injection and tenderness afterwards.
- A flatter look where filler has gone. This is the intended effect, although it can look like too much at first. The area is judged at about two weeks.
- Itching at the site, which usually passes within hours. Itching with a spreading rash is different and needs attention.
Allergy to hyaluronidase
An allergic reaction can be local, with marked swelling, redness and itching around the injection site, or more general, with hives, swelling of the lips or eyelids, wheeze or faintness. Published reports give an overall rate of 0.05% to 0.69%, with hives or angioedema in under 0.1% [1]. Severe reactions are rare, and published guidance for practitioners sets out allergy precautions and emergency readiness [2].
Tell the doctor if you have had a reaction to hyaluronidase before, a bee sting allergy, or an allergy to bovine collagen. A skin test can then be done: a small dose is placed in the skin and observed. A test that shows nothing is reassuring, though delayed reactions can still appear a day later [1]. Where the risk is judged too high, the plan changes: waiting, or managing the filler without the enzyme.
Delayed reactions
A delayed reaction usually shows as swelling, redness, warmth or itching at the treated area, starting some hours to a day or more after the injection. Most are managed with antihistamines or a short course of anti-inflammatory medicine after review. Swelling that keeps increasing, spreads beyond the area, or comes with difficulty breathing is an emergency.
Does it dissolve your own tissue?
Hyaluronidase breaks down hyaluronic acid, including the hyaluronic acid your skin makes naturally. It does not break down collagen, fat, muscle or bone. Your body renews its own hyaluronic acid continuously, so this part recovers. A hollow look after dissolving is usually the face returning to how it was before filler, sometimes with stretched skin that needs time, and not tissue that has been destroyed.
Small, staged doses limit the chance of removing more than intended. See how long hyaluronidase takes to work and dissolving filler in Singapore.
What to tell the doctor
- Any previous reaction to hyaluronidase, including during eye surgery or a drip.
- Bee sting allergy, or allergy to bovine collagen [1].
- Regular medicines. Some, including certain anti-inflammatory drugs, antihistamines and high-dose vitamin C, can reduce the enzyme's effect [1].
- Pregnancy or breastfeeding, where elective dissolving is usually deferred.
- An active skin infection in the area, which is treated first.
Seek help the same day
- Hives or a rash spreading beyond the treated area.
- Swelling of the lips, tongue, eyelids or throat.
- Wheeze, a tight chest, faintness or a racing heart.
- Swelling, heat and pain that keep increasing after the first day.
For breathing difficulty or collapse, call 995.
Frequently asked questions
What are the risks associated with hyaluronidase injections?
The main risks are swelling and bruising, an allergic reaction, and dissolving more filler than intended. Allergy is uncommon, reported in 0.05% to 0.69% of people. Small, staged doses and a review at about two weeks limit over-correction.
What are the potential side effects of hyaluronidase injections?
Swelling, redness, bruising, stinging and tenderness at the site are the usual ones and settle within days. Less often there is itching or a local allergic reaction. Hives, facial swelling or breathing difficulty are rare and need urgent care.
What are the symptoms of a delayed reaction to hyaluronidase?
Swelling, redness, warmth or itching at the treated area that starts hours to a day or more after the injection. It should be reviewed. Swelling that spreads or affects breathing is an emergency.
Does hyaluronidase destroy natural tissue?
It breaks down hyaluronic acid, including some of your own, but not collagen, fat or muscle. The body renews its own hyaluronic acid, so that effect is temporary. Results vary between people.
Who should not have hyaluronidase?
People who have reacted to it before, and those with an infection in the area. People with a bee sting allergy need a skin test or an alternative plan. Elective dissolving is usually deferred in pregnancy.
Do I need an allergy test before dissolving filler?
Not everyone does. A skin test is advised if you have had a reaction to the enzyme, a bee sting allergy or several drug allergies. In an emergency such as blocked blood flow, treatment is not delayed for a test.
How long do hyaluronidase side effects last?
Swelling and redness usually settle in two to three days and bruising within a week. The area is judged at about two weeks, once swelling has gone.
Book an assessment
IN Eternity Clinic, 9 Scotts Road, #12-01 Pacific Plaza, Singapore 228210. By appointment with Medical Director Dr Sin Yong. Monday to Saturday, 11am to 8pm. WhatsApp or call +65 8815 3008. At IN Eternity Clinic a consultation fee applies, and it is waived if you go ahead with any medical treatment; the fee is S
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References
- Jung H. Hyaluronidase: an overview of its properties, applications, and side effects. Arch Plast Surg 2020;47(4):297-300. doi:10.5999/aps.2020.00752
- 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). PubMed
Figures taken from the published papers and abstracts. Results vary between people; suitability is decided at an in-person consultation.