Copyright © 2020 The Korean Society of Plastic and Reconstructive Surgeons
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Hyaluronidase, which is an enzyme that breaks down hyaluronic
acid, has been used in medical applications for over 60 years.
The US Food and Drug Administration has approved hyaluron-
idase for the following indications: (1) subcutaneous fluid infu-
sion (hypodermoclysis), (2) as an adjuvant to accelerate the ab-
sorption and dispersion of drugs in subcutaneous tissue or to
manage extravasation, and (3) as an adjunct to promote the ab-
sorption of contrast media in urinary tract angiography (subcu-
taneous urography) . In addition, it has been approved and
used for the purpose of increasing hematoma absorption in Eu-
rope . Hyaluronidase has a variety of uses in addition to its
approved indications. Its current off-label uses include dissolving
hyaluronic acid fillers, treating granulomatous foreign body reac-
tions, and treating skin necrosis associated with filler injections.
Although the use of hyaluronidase for these off-label indications
has increased significantly, medical practitioners have few op-
Hyaluronidase: An overview of its properties,
applications, and side effects
Gangnam L Plastic Surgery Center, Sejong, Korea
Hyaluronidase, an enzyme that breaks down hyaluronic acid, has long been used to increase
the absorption of drugs into tissue and to reduce tissue damage in cases of extravasation of a
drug. With the increasing popularity of hyaluronic acid filler, hyaluronidase has become an
essential drug for the correction of complications and unsatisfactory results after filler injec-
tion. For this reason, when performing procedures using hyaluronic acid filler, a sufficient
knowledge of hyaluronidase is required. In order for hyaluronidase to dissolve a hyaluronic
acid filler, it must interact with its binding sites within the hyaluronic acid. The reaction of a
filler to hyaluronidase depends on the hyaluronic acid concentration, the number of crosslinks,
and the form of the filler. Hyaluronidase is rapidly degraded and deactivated in the body.
Therefore, in order to dissolve a hyaluronic acid filler, a sufficient amount of hyaluronidase
must be injected close to the filler. If the filler is placed subcutaneously, injection of hyal-
uronidase into the filler itself may help, but if the filler is placed within a blood vessel, it is
sufficient to inject hyaluronidase in the vicinity of the vessel, instead of into the filler itself.
Allergic reactions are a common side effect of hyaluronidase. Most allergic reactions to hyal-
uronidase are local, but systemic reactions may occur in infrequent cases. Since most allergic
responses to hyaluronidase are immediate hypersensitivity reactions, skin tests are recom-
mended before use. However, some patients experience delayed allergic reactions, which skin
tests may not predict.
Keywords Hyaluronidase / Hyaluronic acid / Filler
Correspondence: Hyunwook Jung
Gangnam L Plastic Surgery Center,
SaeromCity Building, 273 Hannuri-
daero, Sejong 30127, Korea
This review article was prepared by the
Botulinum Toxin-Filler-Thread Academic
Association for the Korean Plastic &
Received: April 21, 2020 • Revised: July 1, 2020 • Accepted: July 1, 2020
pISSN: 2234-6163 • eISSN: 2234-6171 • https://doi.org/10.5999/aps.2020.00752 • Arch Plast Surg 2020;47:297-300
Jung H Overview of hyaluronidase
portunities to study hyaluronidase. This article presents the
types and characteristics of hyaluronidase, and also introduces
research results that will be helpful for using hyaluronidase.
ACTION OF HYALURONIDASE
Hyaluronic acid is a glycosaminoglycan, a major component of
the extracellular matrix, and is also a component of fillers that
are frequently used for cosmetic purposes. As shown in Fig. 1,
which depicts the structure of hyaluronic acid, D-glucuronic
acid and D-N-acetylglucosamine are polymers composed of di-
saccharides linked by β-1,4 and β-1,3 glycosidic bonds. Hyal-
uronic acid fillers are made by cross-linking hyaluronic acid
molecules with a plasticizing agent such as 1,4-butanediol digly-
cidyl (BDDE) to stabilize and slow decomposition .
Hyaluronidase is an endoglycosidase that breaks down hyal-
uronic acid into monosaccharides by cleaving its glycosidic
bonds; additionally, to some extent, it also breaks down other
acid mucopolysaccharides in the connective tissue .
TYPES OF HYALURONIDASE
Human hyaluronidase is present both in organs (testis, spleen,
skin, eyes, liver, kidneys, uterus, and placenta) and in body fluids
(tears, blood, and semen) . There are six known types (hyal-
uronidase 1–4, PH-20, and HYALP1). Hyaluronidase 1, which
is encoded by the HYAL1 gene, is present in major organs such
as the liver, kidney, spleen, and heart, as well as in serum and
urine. It acts as a major hyaluronidase in plasma and is activated
at an acidic pH. Hyaluronidase 2 exerts weaker enzymatic activ-
ity than hyaluronidase 1 and only breaks down high-molecular-
weight hyaluronic acid. Hyaluronidase 3 is found only in the
testis and bone marrow, and its role is unknown. Testicular PH-
20 hyaluronidase is found on the surface of human sperm and
inner acrosomal membrane and serves to degrade hyaluronic
acid in the ovum during fertilization .
Meyer classified hyaluronidases into three categories accord-
ing to its mechanism of action. First, mammalian hyaluronidases
are endo-β-N-acetylhexosaminidases that break down β-1,4 gly-
cosidic linkages to form tetrasaccharides. Second, leech/hook-
worm hyaluronidases are endo-β-D-glucuronidases that break
down β-1,3 glycosidic bonds to form pentasaccharides and hex-
asaccharides. Finally, microbial hyaluronidases are classified as
hyaluronate lyases. Unlike other hyaluronidases, they do not
catalyze hydrolysis reactions; instead, they produce unsaturated
disaccharides through a β-elimination reaction at β-1,4 glyco-
sidic linkages (Fig. 1) .
Hyaluronidases can also be classified into two types according
to the pH at which they are most active. Acid-active hyaluroni-
dases are activated at a pH of 3 to 4. Neutral-active hyaluroni-
dases—which includes the hyaluronidase enzymes found in
snake and bee venom—are activated at a pH of 5 to 8 .
In the past, medical hyaluronidase was extracted from bovine
or sheep testicles and used without purification. However, the
mammalian hyaluronidase obtained in this way was low in puri-
ty and contained components that could cause an immune re-
sponse. Subsequently, purification of mammalian hyaluronidase
was implemented as a processing step, and microbial hyaluroni-
dase obtained from Streptococcus agalactiae bacteria was also
used to reduce side effects.
D-Glucuronic acid and D-N-acetylglucosamine are linked by β-1,3 bonds (blue) to form a disaccharide. Multiple disaccharides are linked by β-1,4
bonds (red) to form hyaluronic acid. Mammalian and microbial hyaluronidases cleave β-1,4 bonds (red), and leech/hookworm hyaluronidases de-
grade β-1,3 bonds (blue).
Fig. 1. Structure of hyaluronic acid
Vol. 47 / No. 4 / July 2020
HYALURONIDASE IN THE BODY
When hyaluronidase is injected into the body, its activity gradu-
ally decreases over time as a result of dilution, diffusion, and de-
activation . Deactivation is caused by anti-hyaluronidase ac-
tivity, which proceeds at different rates in subcutaneous tissue
and the plasma. In an experiment using rodents, the half-life of
hyaluronidase in subcutaneous tissue was less than 30 minutes
[8,9], and its activity was partially maintained until 1 hour de-
pending on the experiment . In plasma, the half-life was 2
to 3 minutes when hyaluronidase was injected intravenously in
humans, and even repeated injections did not result in a sus-
tained elevation of serum levels of hyaluronidase [2,5,8]. The
reasons for the short half-life of hyaluronidase in human plasma
are the presence of numerous hyaluronidase inhibitors in the
plasma and the metabolism of hyaluronidase in the kidneys and
Hyaluronidase in the body is affected by various drugs. Hyal-
uronidase antagonists include anti-inflammatory agents (e.g., in-
domethacin, dexamethasone, and salicylates), numerous plant-
based compounds (e.g., flavonoids and antioxidants), antihista-
mines, mast cell stabilizers, heparin, vitamin C, dicumarene, and
radiographic contrast media [2,5].
Levels of hyaluronidase inhibitors may increase depending on
an individual’s physical condition. In acute-phase responses
such as burns, septicemia, and shock, hyaluronidase inhibitor
levels increase to prevent circulatory collapse by reducing the
turnover rate of hyaluronic acid .
HYALURONIC ACID FILLERS AND
In order for hyaluronidase to dissolve a hyaluronic acid filler, it
must be able to access the intramolecular bonds within hyal-
uronic acid. The factors that interfere with access include the
number of crosslinks between hyaluronic acid molecules and
the concentration of hyaluronic acid. The more cross-linking,
the more difficult it is for hyaluronidase to access its binding
sites inside the hyaluronic acid filler. For this reason, fillers with
extensive cross-linking require a long time to dissolve with hyal-
uronidase . In addition, the higher the concentration of hy-
aluronic acid, the slower it will be dissolved by hyaluronidase
. Monophasic fillers are less soluble in hyaluronidase be-
cause they are less exposed to hyaluronidase than polyphasic
As the side effects of fillers on blood vessels are known, many
attempts have been made to effectively dissolve fillers inside
blood vessels. DeLorenzi  concluded in a 2014 paper that
hyaluronidase could be injected subcutaneously without the
need for intravascular injections to treat filler-induced vascular
embolism. In an animal experiment, Wang et al.  also found
that subcutaneous injections of hyaluronidase were more effec-
tive than intravascular injections for preventing skin necrosis
caused by hyaluronic acid filler embolism. The amount of hyal-
uronidase is important when injecting hyaluronidase in the vi-
cinity of a blood vessel to dissolve filler inside the vessel. Lee et
al.  reported that it was effective to inject 30–50 IU or more
in one place in an animal test in 2020, and recommended inject-
ing 100 IU or more at each location for a clear effect.
SIDE EFFECTS OF HYALURONIDASE
Local injections of hyaluronidase can cause side effects such as
local pruritus and allergic reactions. The incidence of allergic re-
actions is reported to be 0.05% to 0.69%, and urticaria and angio-
edema have also been reported to occur at a low frequency (less
than 0.1%) [2,16]. Allergic reactions are more likely to occur
when the hyaluronidase dose is more than 100,000 IU through
an intravenous injection, and the occurrence of allergic compli-
cations rises to 31.3% if the dose increases to 200,000 IU .
Most allergic reactions of hyaluronidase are immediate hyper-
sensitivity reactions (type I, immunoglobulin E–mediated), but
delayed hypersensitivity reactions (type IV, T-cell–mediated)
may also occur . Immediate hypersensitivity reactions
caused by hyaluronidase manifest as erythematous edema after
1 to 2 hours, and there is no response to antibiotic treatment. In
such cases, systemic steroids, antihistamines, and steroid cream
application are helpful . Delayed hypersensitivity reactions
caused by hyaluronidase can occur even after 24 hours, and in
such cases, a skin test will not produce a positive reaction within
20 minutes, resulting in a negative diagnosis .
The skin test is performed with 3 IU of hyaluronidase; al-
though is recommended to perform a skin test before using hy-
aluronidase, doing so can often be difficult in general clinics
. There is usually no link between the patient’s history of al-
lergies and the response to hyaluronidase. However, depending
on the origin of hyaluronidase, injection of hyaluronidase
should be avoided because cross-reactions may occur in patients
who are allergic to bovine collagen and bee stings .
Hyaluronidase use has become more diverse and widespread in
clinical practice. In particular, it is used to address patients’ dis-
satisfaction after hyaluronic acid filler treatment and to treat side
effects. As its use becomes more common, it is increasingly im-
Jung H Overview of hyaluronidase
portant for clinicians to have a sufficient knowledge of hyal-
uronidase. Hyaluronidase can serve as an appropriate treatment
in a variety of situations if it is used with a thorough understand-
ing of its mechanism of action, metabolism, and side effects.
Conflict of interest
No potential conflict of interest relevant to this article was re-
Hyunwook Jung https://orcid.org/0000-0002-1186-7510
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