Hyaluronidase:
what the term means

What hyaluronidase is, and how it works

Hyaluronidase is an enzyme that cleaves the chemical bonds within hyaluronic acid, breaking the cross-linked filler gel into fragments that the body clears through its normal metabolic pathways. It begins working within minutes of placement, and the visible change settles over the following days. It is the reason hyaluronic acid fillers are described as reversible, and that reversibility is one of the strongest arguments for choosing HA in areas such as the tear trough and lips.

It is a prescription medicine, given by injection by a doctor. Two properties shape how it is used. Different HA fillers are cross-linked differently and resist the enzyme to different degrees, so the response to a given dose is assessed rather than assumed. And it does not distinguish injected product from the hyaluronic acid naturally present in tissue, which is why dose and placement are planned from an examination rather than applied by formula.

How hyaluronidase is used in aesthetic medicine

Its planned use is correction: filler that looks heavy or puffy, product that has migrated beyond the area it was placed in, a lump, or the bluish Tyndall tint of hyaluronic acid sitting too superficially under thin skin. Where useful, ultrasound shows where the product sits and at what depth, so the enzyme is directed at the misplaced portion rather than at the whole area. Dissolving is staged conservatively, reassessing between rounds, and published guidance advises waiting a minimum of two weeks after dissolving before any filler is placed again. This is the work described on the filler correction page.

Its urgent use is different in kind. If filler enters or compresses an artery, the skin it supplies loses its blood flow, and published guidelines describe high-dose hyaluronidase as the treatment when an HA vascular event is suspected. It is kept to hand wherever hyaluronic acid filler is injected, and this is one reason to know which product was used; the complication care page explains the warning signs.

“Hyaluronidase dissolves hyaluronic acid and nothing else. If someone offers to dissolve Ellanse or Sculptra, they are describing something that does not happen.”

Dr Sin YongOn what hyaluronidase can and cannot reverse

What hyaluronidase is often confused with

The commonest misunderstanding is that it is a universal undo button for filler. It is not. Hyaluronidase dissolves hyaluronic acid and nothing else: calcium hydroxylapatite, polycaprolactone and poly-L-lactic acid are not enzymatically reversible, and a clinic offering to dissolve Ellansé or Sculptra is describing something that does not happen. Concerns after those products are assessed and managed as the material resorbs, as set out in the comparison of Sculptra, Ellansé and HA filler.

It is also not a fat-dissolving injection, and it does not remove the patient's own tissue. Hyaluronidase can leave an area looking flatter than expected only because the filler was masking genuine volume loss or because it has acted on native hyaluronic acid, which recovers; it does not take away fat or skin.

When hyaluronidase is not the answer

It is not the answer when the fullness is not hyaluronic acid filler. Swelling in the first weeks after injection, fluid retention, weight change and the patient's own tissue can all read as too much filler, and dissolving cannot fix what is not product; recently injected filler often looks worse than it will settle to, so waiting can be the correct decision. Nor is it the answer for non-HA material, or for well-placed product next to a misplaced deposit, where stripping everything leaves a worse starting point.

As a medicine it has its own considerations. A known allergy to hyaluronidase, or a history of significant reactions to bee or wasp stings, raises the risk of an allergic reaction and is asked about beforehand; elective dissolving is usually deferred in pregnancy and breastfeeding and settled first if there is infection or inflamed skin over the area. Swelling, redness, tenderness and bruising at the injection points are common and settle; itching or local swelling can signal an allergic response, which is why patients are observed afterwards. A suspected vascular occlusion is the exception to all of this and is treated as an emergency.