Dermal fillers can be used to reverse the signs of aging, via correction of volume loss over the cheeks/mid face area, over the nasolabial folds, over the jowls and sides of the face.

Dermal fillers can also be used to augment areas of facial deficiencies, like a short chin, a flat nose bridge, a button nose tip, hollowing of the infraorbital rim and thin shapeless lips, thin ear lobes or thin lower eyelids.

Traditionally dermal fillers contain cross-linked hyaluronic acid (HA). HA is found naturally occurring in the human body and cells, although the cross-linked hyaluronic acid  used in dermal fillers are structurally and chemically modified to enhance their rheology and lifespan, hence they cannot be considered “natural”.

Nevertheless, HA dermal fillers are considered biocompatible and have an established safety profile after multiple decades of use. Think of it as “synthetic fat”, we place the HA dermal filler into areas of the face with volume loss or structural defects and it helps to correct the volume loss/defect.

Biostimulators are a heterogenous class of dermal fillers which have been increasing in popularity over the last decade. Biostimulators aim to stimulate collagen growth at or around the areas of injection, aiming to achieve a more “natural” result, though biostimulators, depending on the type used,  may give no immediate effects or only partial effects after injection, and requiring 3 to 6 months for full effects as collagen growth takes time.


The results from HA dermal fillers are immediately visible after treatment, and may appear more natural after two weeks or so.

Minor asymmetry/blemishes/imperfection are quite common with HA dermal filler administration, nevertheless we always put in every possible effort to ensure that we do our best here. The injection of HA dermal filler is really about craftsmanship, and it is very hard to describe in words.

We advocate judicious filling, in part to avoid any state of “over-filling” which looks unnatural.

Biostimulators typically do not deliver the full (or any) results after injection, as the main aim is to stimulate collagen growth. This may take 3 to 6 months for full results.

We only inject dermal fillers using blunt tipped micro cannula for safety reasons. These are blunt tipped long needles (38mm to 50mm length) incapable of penetrating the skin, hence diluted local anaesthetic is injected near (but not at) the site of treatment to create a small needle puncture.

Discomfort or pain arises mainly from the manipulation of the cannula. If the cannula can be manipulated with ease, typically the degree of pain or discomfort will be less. Factors which can cause difficulty with cannulation are areas of the face being treated, presence of scarring/fibrosis from previous interventions (e.g. implant, surgery, fat graft etc.) and presence of ligaments and similar structures.

From our experience, the pain levels associated with dermal filler treatment (based on area) are as follows:

Mild Pain (+)



Mild-Moderate Pain (++)




Jowls/Sides of Face/Marionette Lines

Moderate Pain (+++)



Intense Pain (++++)


Excruciating Pain (+++++) 


Of course, pain perception is highly relative, and the above is meant to serve only as a guide.

At YVL Medical Aesthetics, we currently only carry selected HA dermal fillers from the following brands:

  • Restylane
  • Teoxane
  • Juvederm

Different dermal fillers have different rheology (i.e. gel property) and this affects how the treated area shapes up after injection. Hence, different parts of the face will require different types of gel.

Therefore there is no such thing as a “superior” or “best” dermal filler. There simply isn’t a one size that fits all, and each individual doctor, based on his/her experience, may recommend different fillers for different parts of face. Similarly, as our doctor’s injection preferences evolve, our filler offering may change as well.

Risks of HA dermal fillers include:


HA dermal fillers can get infected shortly (i.e. days) after injection, typically beginning from the injection site. Less commonly, late infection of HA dermal fillers can occur weeks to months after the initial injection.


HA dermal fillers are synthetic as mentioned earlier, and are perceived by the human immune system to be foreign particles. On rare occasions, the immune system may malfunction and attack the HA fillers and form hard lumps known as granulomas.

This can be triggered by a recent viral infection (e.g. flu, gastroenteritis) or after heavy drinking.

Granulomas tend to occur much later after the initial injection (i.e. months to years) and can occur with any type of dermal filler. Very often, there may not be palpable filler left.

Tyndall Effect

This occurs from HA dermal filler being placed too close to the skin surface, causing a greenish discolouration in most Asian patients. This commonly happens over the under-eye area.

The above mentioned side effects may be treated with a combination of the following:

  • Hyaluronidase to dissolve the HA dermal filler
  • Steroids
  • Antibiotics

Biostimulators may also get infected or form nodules. Nodules may represent collagen formation too superficially and hence palpable. Unlike HA dermal fillers, there is no enzyme that can readily dissolve non-HA biostimulators, although the treatment principles are by and large the same.

The most feared complication of dermal fillers is Filler Induced Vascular Occlusion (FIVO). This complication is very rare but is considered an emergency.

Dermal fillers, whether HA or biostimulators are typically particulate in nature. The filler particles have been known to cause obstruction in the arteries of the face, and in severe cases, the filler particles can embolize through these arteries and block the eye arteries, resulting in blindness, and even cause strokes and death.

Obstruction of arteries of the face may cause lack of blood supply to supplied skin regions, resulting in necrosis and sloughing of the affected areas. Without intervention, this may take weeks to heal and may scar.

Obstruction of the eye arteries are extremely rare. As of 2023, there has been around 400 cases in global reported literature, with at least 40 million syringes of dermal fillers being performed worldwide, putting the incidence at less than 1 in 100,000. Anecdotally, there may have been seven or eight cases in Singapore. The retina is extremely sensitive to oxygen deprivation, and irreversible retinal death may start as early as 15 minutes after oxygen deprivation. Blindness can be severe and permanent and in most cases, the visual recovery is poor.

Obstruction of the brain arteries are even rarer, this occurs in 20% of filler induced blindness cases.

All these complications are severe and must be considered emergencies. Immediate injection of hyaluronidase to dissolve any injected filler is a definitive remedial action, and in cases whereby there is visual loss or stroke, emergency transfer o hospital/specialist care is needed and inpatient treatment is required.

Now, the risk of FIVO can be reduced through the following:

Usage of Blunt Tipped Micro Cannula

The use of blunt tipped micro cannula 25G and larger by skilled practitioners has been associated with reduced risk of FIVO. This is because the blunt tip design reduces the chances of perforating an artery, and the cannula design allows for lower injection pressures.

Which is why we only use the blunt tipped micro cannula for dermal filler injections.

Slow Injection Technique

For dermal filler material to be injected into the artery, the injection pressure must exceed the blood pressure (basic physics). Now, it has been shown that with a traditional small hypodermic needle injection, the injection pressure can exceed many times the systolic blood pressure (the hypodermic needle lumen being narrow).

A gentle and slow injection, coupled with the skillful use of blunt tipped microcannula is a necessary technique to reduce the risk of FIVO. A third consideration here is the rheology of the dermal filler gel being used. Our doctor does not favour dermal filler gels that are very “stiff” and cannot be injected with ease.

Understanding Risk Areas

For FIVO resulting in blindness, the commonest high risk areas are:

  • Nose
  • Glabella
  • Forehead

in that order, whereas for skin necrosis, in addition, the nasolabial region is also considered high risk.

HA dermal fillers are commonly quoted as being able to last between 6 to 12 months. However the variability between individuals is great. On rare occasions, we have seen cases resorb HA dermal filler within weeks, or last longer than 5 years. The amount of filler placed as well as the area administered may also affect the longevity of the HA dermal filler. We have observed that certain areas of the face seem to absorb HA dermal filler much slower, like the under eye area (which may not produce much hyaluronidase).

As HA dermal fillers are essentially synthetic, they do not absorb 100%, although they are generally largely absorbed with time. The remnant HA dermal filler is not known to have any deleterious side effects to the body, and should not be the cause for any health concerns.

Hyaluronidase is the enzyme that is used to dissolve HA dermal fillers. It may used in very large doses in an emergency setting like during FIVO, or it may be used in smaller quantities to dissolve previously administered HA dermal filler.

By controlling the quantity of hyaluronidase administered, we can effect partial dissolution of the HA dermal fillers, in cases where “over-filling” has occurred and whereby the intended effect is to remove only the “excess” filler (and not all). This commonly happens in the under area, the cheeks, and the lips.

There is a common misconception that hyaluronidase also dissolves our own body’s HA which results in wasting/sinking/loss of tissue. Hyaluronidase does dissolve the body’s own HA at/around the area of injection, but naturally occurring HA has a half life of only 48 hours. This means that 50% of our body’s HA is being degraded every 2 days in a natural state, and the body is fully capable of producing an equivalent amount to balance the degradation. Hence there is no wasting/sinking/loss of tissue from hyaluronidase injection, and in non-allergic patients, high dose hyaluronidase is not harmful.

Contact us today to set up a consultation and learn more about what treatment is best for you.