Most of the complications associated with Hyaluronic acid filler treatments are mild, transient and reversible. Nevertheless serious complications due to vascular occlusion leading to cutaneous necrosis and blindness can occur due to direct intravascular filler injection.

A thorough understanding of the facial vascular anatomy reduces the risk of vascular occlusion, but due to vascular anatomical variations there is almost a minimal risk of intravascular injections. Early identification of a vascular occlusion and a prompt intervention using Hyaluronidase can decrease the risk of long term sequelae.

As soon as HA is injected into an artery this immediately can cause a clot formation or the filler itself may cause vascular occlusion leading to skin necrosis, or even blindness.

When injected into a vein, HA can also cause a blockage, resulting in blood flowing back into the tissues and therefore increasing pressure and causing low grade ischaemia.

Risk areas

The 3 most risky areas for vascular complications following HA procedures are: Nose, gabella, nasolabial fold

It is crucial that throughout the procedure the practitioner must observe for signs of blanching of the skin, which might occur immediately during the injection. Due to the fact, that most of the HA fillers contain Lidocain, no pain might be felt as it is under the treatment of HA´s without Lidocain. Nevertheless, if skin whitening is ignored, the area may turn blue after several hours and tissue necrosis can occur after days.

Hyaluronidase (an enzyme that act as dispersion agent, which speeds up the natural breakdown of hyaluronic acid through hydrolysis) should be administered immediately after a skin blanching is noticed. There is good evidence that tissue necrosis can be prevented or be less severe the sooner the hyaluronidase is injected.

Hyaluronidase must be used early, as its effectiveness in dissolving HA fillers is reduced after approximately four hours.

Complication of Hyaluronidase

According to clinical studies, allergic reactions following Hyaluronidase injection may occur in 0,05% to 0,69% Therefore an intradermally patch test (signs of inflammation or erythema) should be carried out to minimise the risk.

However, if the patient is showing signs of a vascular compromise then it could be justifiable to use the Hyaluronidase as soon as possible to lower the risk of further harm.

After Hyaluronidase treatment the patient should be observed for at least 30 minutes in a clinical environment. Results are often seen almost immediately after the injection. More cross-linked products may take longer for the effects to be seen. We advise hourly injections of 500-I500 IU of Hyaluronidase till an improvement shows up. We also would advise to see the patient in the office each day after the treatment till the problem is completely solved. If no improvement shows, repeated Hyaluronidase injections should be performed till the first visual improvement.

There is no evidence that Hyaluronidase might alter the body´s own Hyaluronic acid. Therefore first signs of vascular injections must be treated as soon as possible and with an adequate amount of Hyaluronidase.