In short
- It is an enzyme that breaks down hyaluronic acid: it dismantles the injected filler, it does not make the body “reabsorb it sooner”.
- It is the treatment for vascular occlusion, and the guidelines agree on giving it as early as possible in that setting.
- It is not the answer to everything that looks like a lump. The 2024 consensus reserves it for non-inflammatory reactions with no active infection; in inflammatory ones, watchful waiting or a steroid may be preferred, and if there is an infection what is called for is drainage, culture and an antibiotic.
- It does not work on permanent materials. If what was injected was not hyaluronic acid, there is nothing to dissolve.
- It carries a risk of allergy, and the guidelines point out that a history of allergy to bee or wasp stings raises that risk through cross-reactivity.
- 🔑 In Spain there is no registered medicine containing hyaluronidase. The AEMPS warned in 2025 that it is also sold as a cosmetic, in similar-looking vials, and that injecting the cosmetic is malpractice. It is the most useful thing you can ask before it is given to you.
- For dissolving filler, its use is outside the product licence — off-label — in the United Kingdom and the United States too, and the guidelines require that you be told so.
- Allergy is the most feared risk and rarer than people think: since 1949 there have been four published cases of an allergic reaction requiring adrenaline.
Hyaluronidase is the underlying reason hyaluronic acid is preferred to permanent fillers: it is an enzyme that breaks hyaluronic acid apart, so it allows what has been injected to be undone. That makes filler reversible, and in a vascular emergency it is simply the treatment.
But it is not a universal eraser or a catalogue product. It is an injectable medicine, it has risks of its own — allergy among them — and there are situations in which giving it is exactly what should not be done. This page explains all three things.
This page expands on the reversibility of hyaluronic acid treatments. The emergency in which it is used against the clock is in vascular occlusion: warning signs.
What it is and what it does exactly
The hyaluronic acid in a filler is not the same as the body’s own: it is cross-linked, meaning it is chemically bonded into a three-dimensional mesh that holds water and supports volume. That cross-linking is what makes it last months instead of days.
Hyaluronidase cuts those bonds. The mesh comes apart, the gel loses its structure and the body clears the fragments. Hence the two consequences that matter:
- What is undone is what was injected. If the volume you can see is not product but swelling, or your own tissue, hyaluronidase is not going to change it.
- On a permanent material it does nothing. There is no hyaluronic acid mesh to cut. It is the most important practical difference between a reversible filler and one that is not, and it is set out in the page on biopolymer removal.
When it is used
The safe-use guideline published in 2021 sets out four indications for dissolving a hyaluronic acid filler. It is worth keeping them in order, because they do not all carry the same urgency or the same criteria.
In an emergency: vascular occlusion. This is the treatment, and the factor that decides the outcome is speed: the guidelines recommend giving it as early as possible and reassessing until the picture resolves. That setting is described separately because it has warning signs of its own.
When the product is too superficial. The guideline expressly cites the Tyndall effect: the bluish tinge that appears when filler is placed in a more superficial plane than it should be. It is particularly visible under the eyes, where the skin is thin.
When the result is not the one sought. Incorrect placement, too much product or migration of the filler. There is no hurry here, and for that very reason it is worth not rushing: some of what is visible in the first few weeks is swelling and not product.
For certain late nodules, the ones that appear weeks or months afterwards. And here is the nuance that is almost never told properly.
When it is NOT the answer
The consensus published in 2024 on late reactions to hyaluronic acid separates three scenarios, and each one calls for a different course of action:
| Situation | What the consensus recommends |
|---|---|
| Non-inflammatory reaction, no active infection | Hyaluronidase |
| Inflammatory reaction | Watchful waiting or a steroid |
| Infection | Drainage, culture and an antibiotic — not hyaluronidase |
Put another way: a lump is not dissolved by default. Giving hyaluronidase on top of an infection does not solve the problem and may complicate it. That is why the first thing is not the medicine, it is the diagnosis.
The risks it does carry
It is often presented as a trivial manoeuvre. It is not.
- Allergy. It is the risk that most shapes the decision, and the one explained worst. It has a section of its own a few lines below, with the figures.
- Dissolving too much. The enzyme does not distinguish between the product that is surplus and the product that is well placed, nor between the filler and the area’s own hyaluronic acid. Overtreatment can leave the area emptier than it was before starting.
- Local discomfort: pain, swelling and bruising at the injection site.
- It is not always a single session. Sometimes it has to be repeated, and time is allowed between one and the next to assess the real result.
Allergy, with the figures in front of you
It is what people fear most, and it deserves figures rather than vagueness.
How many cases there are. Since hyaluronidase came into medical use in 1949, four cases have been published of an allergic reaction requiring adrenaline. Referring specifically to dissolving hyaluronic acid filler, the 2021 guideline finds three publications, with four patients in total. The incidence, therefore, is very small.
The 0.1% quoted everywhere. It circulates as a hypersensitivity rate, but the guideline points out that the figure covers all allergic reactions and not only the immediate type, which is the serious one. They are not the same thing.
What kind of reaction is the usual one. Mostly local type IV reactions, that is, those appearing from an hour onwards. An immediate systemic reaction is exceptional except with high intravenous doses. And one nuance that prevents a lot of frights: facial swelling on its own is not anaphylaxis, and it is expected to settle spontaneously within 12 to 24 hours.
Bee and wasp stings. Hyaluronidase is one of the allergens present in bee and wasp venom, hence the cross-reactivity. That is why it is a history that must always be declared. With one important clarification: the figures the guideline uses in these patients — more than a 5% risk of anaphylaxis on a fresh sting if there was an extensive local reaction, and at least 60% if there was previous anaphylaxis — refer to the risk from another sting, not to the risk from hyaluronidase. They serve to gauge who needs to be treated with particular care.
And a skin test beforehand? It is the logical question, and the guideline does not settle it. For two reasons: there is no validated concentration for testing hyaluronidase allergy, and the intradermal test itself carries a risk of anaphylaxis precisely in the patients with a history of an extensive reaction or anaphylaxis from a sting, who are the ones you would most want to test. In other words: the test is not a harmless formality that settles the question.
The formulation counts too. Most products are derived from ovine or bovine testis. There is also recombinant human hyaluronidase, the purest formulation, with no documented cases of allergy.
What the protocols say
Published protocols do exist, and it is worth knowing they are there and on what logic they work, even though the person applying them is a doctor.
In vascular occlusion, it is treated to effect. The 2021 guideline proposes reconstituting 1,500 units of hyaluronidase in 1 ml of 0.9% bacteriostatic saline or 1–2% lidocaine, and infiltrating them — with a needle or cannula — along the course of the affected artery. Then firm massage, a check of capillary refill and repetition every 15–20 minutes until the picture resolves. The phrase that sums up the approach is exactly that: treat to effect, rather than giving a single dose and waiting.
Outside the emergency there is no single figure, and there is a reason for that: the amount depends on the product injected, the volume, the area, the plane and the time elapsed. That is why the guidelines describe a framework for action and not a dosing table.
And there is a practical detail almost nobody mentions: the product is stored below 25 °C and, once the ampoule is opened, it must be used immediately.
What the AEMPS warned about in 2025
This part is the most useful on the whole page if you are in Spain, and it is the one almost no website mentions.
In its information notice of May 2025, the Spanish Agency for Medicines and Medical Devices pointed out that there is no registered medicine containing hyaluronidase in Spain. Clinics can obtain it as a foreign medicine, through the AEMPS’s own service for medicines in special situations.
The problem that prompted the notice is that hyaluronidase is also sold as a cosmetic, in vials and ampoules of similar appearance. And the Agency is categorical: the injection or intradermal or systemic application of a cosmetic product is not permitted. Cases have been documented of clinics administering hyaluronidase labelled as a cosmetic — with “do not inject” printed on the packaging itself — which the AEMPS describes as a serious risk to public health. Injecting the cosmetic is malpractice.
Its recommendations to the public are two, and they are easy to remember:
- Ask for information about the product that is going to be used on you, before the procedure.
- Make sure that whoever administers the filler and the hyaluronidase is a qualified doctor.
It is also worth knowing that, for dissolving hyaluronic acid filler, the use of hyaluronidase is outside the product licence — in the United Kingdom and the United States too — and the guidelines establish that the patient must be told so.
What to ask at your appointment
- Is what I have product, swelling or infection?
- Is there a reason to dissolve now, or does it make sense to wait?
- Is the hyaluronidase you are going to use a medicine, not a cosmetic?
- Have I been asked about allergies, including to bee or wasp stings?
- What happens if more than necessary is dissolved?
- Who is going to administer it?
Book an appointment
You can book your own appointment. Pick the day and time from the free slots in the diary, in a panel that opens right here, without leaving this page.
Frequently asked questions
Does hyaluronidase dissolve any filler?
No. It only acts on hyaluronic acid. On permanent materials it does nothing, and there removal is surgical.
I have had filler and I do not like it — can I have it removed?
Generally yes, because hyaluronic acid is reversible. First it is worth assessing whether what is bothering you is product or swelling from the first few weeks, and whether dissolving is what is called for or only what appeals.
Does it hurt?
It is one more injection, with local discomfort much like that of the filler itself: pain at the site, swelling and sometimes bruising.
Could I be allergic?
It is possible, but it is uncommon: since 1949 four cases have been published of an allergic reaction requiring adrenaline, and only four patients in the specific setting of dissolving filler. The usual picture is late local reactions. Allergy to bee or wasp stings does raise the risk through cross-reactivity, so it is a history that must always be declared.
Should I be given an allergy test beforehand?
There is no settled answer, and the 2021 guideline acknowledges as much: there is no validated concentration for testing hyaluronidase allergy, and the intradermal test itself carries a risk of anaphylaxis precisely in patients with a history of a serious reaction to stings. It is judged case by case; what is never missing is the question about that history.
How do I know I am being given real hyaluronidase?
By asking. The AEMPS warned in 2025 that it is also sold as a cosmetic, in similar packaging and marked “do not inject”, and that there have been clinics that injected it anyway. There is no registered medicine containing hyaluronidase in Spain: it is obtained through the AEMPS’s own foreign-medicines route. It is legitimate to ask which of the two you are going to be given.
Will it leave me with a hollow?
It can happen if more product than necessary is dissolved, or if the area’s own hyaluronic acid is degraded as well. It is one of the reasons the dose is adjusted and it is sometimes done over more than one session.
I have a lump months later — should I have hyaluronidase?
It depends on what that lump is. The 2024 consensus only indicates it in non-inflammatory reactions with no infection; if there is inflammation or infection, the course of action is different. It is assessed first.
How long does it take to see the effect?
The volume starts to give way within days, although the real assessment is made after some time has passed, once the swelling from the injection itself has gone down.
Can I have filler again afterwards?
Usually yes, leaving an interval. When, and with what product, is decided at the appointment, according to the reason it was dissolved.
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). Four indications for dissolving hyaluronic acid filler — vascular occlusion, Tyndall effect, late nodules and an unsatisfactory aesthetic result; modified high-dose protocol with reconstitution of 1,500 units in 1 ml of 0.9% bacteriostatic saline or 1–2% lidocaine, infiltration along the course of the artery and repetition every 15–20 minutes, treating to effect; four cases published since 1949 of an allergic reaction requiring adrenaline and three publications with four patients in the setting of dissolving filler; the 0.1% usually quoted covers all allergy and not only type I; a predominance of local type IV reactions; cross-reactivity with bee and wasp venom; the absence of a validated concentration for skin testing and the risk of anaphylaxis from the intradermal test itself in patients with a relevant history; ovine, bovine and recombinant human formulations; off-label use in the United Kingdom and the United States with an obligation to inform the patient. https://pubmed.ncbi.nlm.nih.gov/34840662/
- Spanish Agency for Medicines and Medical Devices. La AEMPS informa sobre el uso correcto de la hialuronidasa. AEMPS information notice 13/2025, 6 May 2025. There is no registered medicine containing hyaluronidase in Spain and it may be requested as a foreign medicine through the service for medicines in special situations; it is also sold as a cosmetic in similar formats; the injection or intradermal or systemic application of a cosmetic product is not permitted, and injecting hyaluronidase classified as a cosmetic constitutes malpractice; cases have been documented that the Agency considers a serious risk to public health. https://www.aemps.gob.es/informa/la-aemps-informa-sobre-el-uso-correcto-de-la-hialuronidasa/
- 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. 2024;14(7). Hyaluronidase is recommended in non-inflammatory reactions with no active infection; in inflammatory ones, watchful waiting or a steroid may be preferred; infectious ones require drainage, culture and an antibiotic. https://pubmed.ncbi.nlm.nih.gov/38907876/
- Murray G, Convery C, Walker L, Davies E. Guideline for the Management of Hyaluronic Acid Filler-induced Vascular Occlusion. J Clin Aesthet Dermatol. 2021. https://pubmed.ncbi.nlm.nih.gov/34188752/
- Beleznay K, Carruthers JDA, Humphrey S, Carruthers A, Jones D. Update on Avoiding and Treating Blindness From Fillers: A Recent Review of the World Literature. Aesthet Surg J. 2019. https://pubmed.ncbi.nlm.nih.gov/30805636/
Book your consultation
If you have had filler and want it undone, or you have a lump and do not know what it is, the first thing is not the medicine: it is knowing what is there. At a face-to-face assessment the area is examined, we go over what product was placed and when, and we decide whether dissolving, waiting or treating something else is what is called for.
ICPM keeps hyaluronidase on site, and we also see people who were injected somewhere else, during consulting hours.
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Last reviewed: 23 August 2026. This content is for information only and does not replace an individual assessment by a healthcare professional.
