Lip Filler

What is lip filler?

Lip filler is the placement of hyaluronic acid gel in and around the lips by injection. According to a review of the anatomy of the lips and the philtrum (the groove between the nose and upper lip), hyaluronic acid products are described as the first-choice type of filler for this treatment because they are compatible with the tissue and reversible.

The approach has also changed over time. Rather than simply making the lips bigger, the current approach focuses on restoring natural contours and addressing age-related changes around the lips. Managing expectations properly is also considered part of the treatment. In other words, it is not only about volume: the lip border, the shape of the lips and the area around them are assessed together.

The strongest evidence in this area comes from randomised controlled trials, that is, comparative studies in which participants are randomly assigned to groups. In an analysis that pooled 16 randomised trials, effectiveness and patient satisfaction were moderate to high; side effects were reported as common, and serious side effects as rare.

Hyaluronic acid gel is broken down by the body over time, which means it is temporary; it can also be dissolved by administering the enzyme hyaluronidase. This is the key feature that sets lip filler apart from permanent synthetic substances. When the clinic assesses a product, approval by the US Food and Drug Administration (FDA) is not a criterion on its own; the assessment is based on the product's CE marking, its registration and conformity status in Türkiye, and the manufacturer's intended purpose.

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Lips that thin with age

As we age, the lips do not only lose volume. Alongside volume loss, thinning of the lip border (vermilion border) and flattening of the groove between the nose and upper lip (philtrum) are also among the age-related changes that noticeably affect how the lips look.

There is a muscle side to the change too. In a study that examined the ring-shaped muscle around the mouth (orbicularis oris) with high-resolution ultrasound, the muscle angle decreased significantly with age in 30 volunteers aged 20 to 60. This decrease was particularly marked in women and most marked in the upper lip, and it was associated with the lips taking on a more inward-turned shape. However, the study is small; the findings need to be confirmed in larger groups.

Ageing around the lips does not look the same in everyone. According to a consensus on the lower face reached by doctors from different specialties, thinning of the tissue around the lips and lines are more prominent in people of European descent, while a receding chin and heaviness along the jawline are more common in groups of East and South Asian descent.

What this means for you: thinning of the lips is only partly explained by the volume loss that filler targets. The same solution does not apply to changes in the muscle or to skin changes around the lips. Which of these is most prominent in your case is worked out at your consultation.

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Lip contour, proportion and asymmetry

With lip filler, the main question is often not ‘how much’ but ‘in what shape’. Under one proposed classification, the complexity of a lip treatment is assessed under five headings: the relative volume of the lips, their shape and symmetry, signs of ageing around the lips, tissue quality and previous treatments. In this classification, mild asymmetry counts as a moderately complex case. However, this is a conceptual proposal that still needs to be validated.

On proportion, the emphasis is not on a single ideal but on individual and cultural differences. According to expert consensus on the lower face, the lips, chin and jawline are key to facial proportions; however, the structure of this area, the way it ages and aesthetic expectations differ between ethnic groups. For this reason, it is recommended that treatment is shaped around the person's own facial structure and how they see themselves.

An international expert panel that came together to define what a natural result is sums up the principle in one sentence: treat the patient, not the photograph. The panel does not limit naturalness to appearance alone; it also takes into account how the result feels to the touch, how it feels to the person and facial expression, and regards safety as the foundation of all this.

A study on perception points in the same direction. A total of 263 participants rated computer-altered images of faces from their own ethnic group; when lip volume was increased, attractiveness scores fell in both groups, and faces with more than one area altered at the same time were rated as less attractive. This is an experimental image study; it is not a benchmark for your personal decision.

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Lines around the lips

Lines around the lips are not all the same, and not all of them are treated with filler. The lines assessed separately in this area are:

• Vertical lines on the upper lip.
• Slanting lines between the lip and the chin.
• The crease between the lip and the chin.
• The line in the middle of the chin.
• Lines running down from the corners of the mouth (marionette lines).

For these lines, a low-viscosity hyaluronic acid is usually injected superficially. For lines caused by muscle movement, filler may be combined with muscle-relaxing botulinum toxin (often called Botox®). In other words, a line that only shows when you move and a line that is also visible at rest may not have the same solution.

The blood vessel anatomy of the area matters here too. In the area between the lip and the chin, care is needed around structures such as the artery that runs horizontally there and the superficial branches of the facial artery. Because the course of blood vessels can vary from person to person and sometimes follows an unusual path, an individual approach is important.

According to expert consensus, in people of European descent, thinning of the tissue around the lips and lines are prominent signs of lower face ageing. Whether a line comes from volume loss, skin changes or muscle movement is worked out at your consultation; if a decision is made without this distinction, expectations and results will not match.

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Lips that have had filler before

If you have had lip filler before, the first question is not a new treatment but what the existing filler is. Studies of filler complications that led to permanent damage show that hyaluronic acid fillers continue to be preferred because they are reversible, while permanent fillers increase the risk of complications in the long term.

A severe example of this risk in the lips was seen in a recently reported patient. After injections of permanent filler, the body developed a foreign body reaction to the filler, meaning that it recognised the filler as a foreign substance and reacted to it; this eventually led to tissue death (necrosis) across the whole of the upper and lower lips. The lips could only be repaired by surgically removing the tissue and transferring tissue from another part of the body. This is a single patient and does not tell us how often this happens; but it shows why permanent substances are questioned separately.

Late reactions are not limited to permanent fillers. When studies on adverse reactions to lip filler were brought together, the most commonly reported condition was foreign body granuloma (an inflammatory lump that forms in reaction to the filler), and hyaluronic acid was the filler most often used in the reported cases. The median time until a granuloma appeared was reported as 24 months. In one proposed classification, signs of previous aesthetic treatments are also among the findings that place a lip treatment in the most complex group.

If you have had filler done elsewhere, you are first asked about the type of filler, when it was done and where it was placed. Filler of unknown type (a filler whose contents are not known), or filler that cannot be confirmed to be hyaluronic acid, is not dissolved straight away. If you have any record of the previous treatment, this information is useful at your consultation.

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How long does it last, and can it be reversed?

Hyaluronic acid lip filler is not permanent; its effect fades over time, and how long it lasts varies from person to person. In an analysis that pooled lip filler studies, the proportion of people with an increase of at least one point in lip fullness was calculated as 91% at 2 months after treatment, 74% at 6 months and 46% at 12 months.

These figures are not a promise of how long the effect will last. They are averages from studies using different products, different techniques and different rating scales; well-designed randomised trials are still needed to strengthen the evidence. How long the effect lasts depends on the product, the technique and the person.

What sets hyaluronic acid apart from other types of filler is that it is reversible: the enzyme hyaluronidase can dissolve this gel. The situations in which the enzyme is considered fall into two groups. Non-urgent situations include non-inflammatory nodules (small lumps you can feel), a bluish discolouration under the skin (Tyndall effect) and hypersensitivity reactions. Vascular occlusion and vision loss, on the other hand, are emergencies and need treatment without delay.

Not every lip filler responds to the enzyme in the same way. In a laboratory study comparing six lip fillers on the market, the rates at which they were broken down by hyaluronidase differed significantly; this difference was thought to be due to differences in the products' cross-linking and formulation. This is a laboratory finding and does not directly show what will happen in people. Hyaluronidase is kept at the clinic.

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Limits of this treatment

Lip filler gives the lips volume and contour support; beyond that, its effect is limited. Ageing of the lower face involves interlinked processes such as changes in bone structure, soft tissue moving downwards and increased muscle activity. Lip filler addresses the volume-related part of these processes.

In practical terms, this means:

• Hyaluronic acid fillers are not permanent; they break down in the body over time, and the treatment may need to be repeated for the effect to continue.

• For lines caused by muscle movement, filler on its own may not be enough; for these lines, filler may be combined with botulinum toxin.

• Adding more volume to the lips does not make the result more harmonious. It has been reported that excessive or inappropriate use of filler can cause distortion of shape when the face is at rest and unnatural facial movement.

• Even in the studies that provide the strongest evidence, side effects are common; serious side effects are rare, but the chance of them happening is not zero.

• Lip filler is not a substitute for surgical procedures.

The aim of this information is not to put you off but to give you a basis for comparing your options. Filler, another method or none at all: which of these makes sense for you is decided by the assessment at your consultation and by your own decision. Having no treatment at all is also a valid outcome.

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Filler migration and an overfilled look

Two unwanted appearances receive particular attention with lip filler: the filler moving away from where it was placed (filler migration), and the lips taking on an overfilled look that is out of harmony with the rest of the face. Neither is regarded as an inevitable result of the product; both are seen as related to planning and technique.

Migration has an anatomical basis. In a study that examined the lips of 126 people with ultrasound, the layer under the skin in the upper and lower lips was on average less than one millimetre thick, and in most people who had had filler, the filler had settled within the muscle. A vertical injection technique was found to be associated with deeper placement, increased blood vessel formation and signs of filler migration. The same study also reported that lip anatomy differed significantly by sex, ethnic background, body mass index and age.

According to an assessment based on the views of international experts, the risk of gel migration and overfilling does not come from the product itself; it is linked to insufficient anatomical knowledge, inappropriate injection technique, or inappropriate patient selection and patient information.

An overfilled look is also described as ‘facial overfilled syndrome’. The problem here is not only too much volume: placement that does not fit the anatomy, disruption of tissue mechanics (the way the tissue stretches and moves) and the build-up of repeated treatments all play a part. The condition shows up as distortion of shape when the face is at rest and unnatural facial movements; the main emphasis is on preventing the problem in the first place.

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Blood vessel anatomy of the lips

The lips are one of the areas of the face with the densest network of blood vessels; no layer of the lip can be considered completely free of blood vessels. The upper lip is supplied by the upper lip artery (superior labial artery) and the lower lip by the lower lip artery (inferior labial artery); the course of these vessels varies markedly from person to person.

In an analysis that pooled 23 studies, the upper lip artery was absent in 3.55% of cases and the lower lip artery in 13.45%. When present, both most often ran under the mucosa, that is, just beneath the lining that covers the inner surface of the lip; their average depth was reported as about 5.2 mm. For this reason, the recommendation is not to define a single safe layer, but to tailor the injection technique to each person's anatomy.

Another study, which also included cadaver examinations, reported that the arteries mostly ran under the mucosa or within the muscle and only rarely under the skin, that the vessels from the two sides join in the midline of the lip, and that the position of the artery is more variable to either side of the midline. In a cadaver study focusing on the lower lip, the lower lip artery was found in 90% of the cadavers, and it was concluded that the blood supply to the lower lip varies markedly from person to person.

There is no single right answer on technique either. A review covering 16 studies and 3,692 patients found no evidence that a needle is superior to a cannula (a fine, flexible tube with a blunt tip) or vice versa, or that any one injection technique is superior to another. At the clinic, the doctor chooses a needle or a cannula for each person according to the treatment area and anatomy; no fixed template is used.

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Known risks

The most common side effects of lip filler are swelling, bruising, tenderness and firmness you can feel; these are mostly temporary. In the analysis that pooled 16 randomised controlled trials, these were also the most commonly reported side effects; side effects were common, while serious side effects were rare.

Another analysis, which also included non-randomised studies and was based on 1,496 participants, likewise reported tenderness, swelling at the injection site and bruising as the most common. Rare events included foreign body granuloma (0.6%), cold sores (herpes labialis, 0.6%) and angioedema, that is, sudden swelling deep under the skin (0.3%). These figures are averages from published studies, not results from this clinic.

Cold sores are a separate issue. It is accepted that trauma to the tissue can reactivate the cold sore virus; this is considered rare, but there are no reliable data on how often it happens. A guideline prepared for cosmetic procedures recommends asking about a history of cold sores before treatment. In a study that followed 90 people with a history of cold sores, there was no significant change in how often outbreaks occurred after the first filler session; however, no cause-and-effect relationship can be drawn from this finding.

Delayed inflammatory reactions are rare, but they can appear months or even years later. In an analysis covering treatments of the face, the frequency was calculated as about one event for every 2,000 patients followed for one year. The median time until symptoms started was 3 months; the shortest was two weeks and the longest was 12 years. Common presentations are nodules, redness, swelling and hardening.

Expert consensus recommendations highlight appropriate patient selection, consent and patient information, preparation and injection technique as ways to reduce risk. Before the procedure, you will be asked about blood thinners, antiplatelet medicines (which stop blood platelets from clumping together) and supplements that can affect bleeding. Do not stop any prescribed medicine on your own. If needed, the procedure is planned or postponed after consulting the relevant doctor.

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How is vascular occlusion recognised?

The most serious complication of lip filler is disruption of the blood supply to the tissue, caused by filler entering an artery or pressing on the vessel from the outside. It is rare, but recognising it early determines the outcome: quick recognition and treatment are key to reducing the risk of skin necrosis (death of the skin), scarring and long-term damage.

In an international multicentre study of 100 patients diagnosed with filler-related blood vessel problems in the face, the most common findings were a net-like, purplish mottling of the skin (livedo reticularis), skin blanching (the skin turning pale or white) and pain. The area around the lips was also among the most commonly affected areas.

Not every swelling or discolouration means a blocked artery (arterial occlusion). In two reported cases of young women, a rapid increase in lip volume and purple pooling of blood developed shortly after treatment around the lips; the findings were judged to be more consistent with a blockage of blood flowing back through the veins. Both women were given hyaluronidase on the same day and recovered without tissue loss. This condition needs to be distinguished from arterial occlusion, angioedema and a collection of blood under the skin (haematoma).

Vision is also part of this topic. One patient has been reported who developed vision loss after lip filler; this was suspected to have been caused by a blocked artery supplying the eye. Despite treatment, the patient's vision did not return. This is a single patient, but it shows that the lips are not entirely free of this risk either.

According to expert consensus, when tissue damage caused by a blood vessel problem is suspected, a quick diagnosis and starting hyaluronidase treatment without delay are crucial. Before your treatment, you should be told how to contact the clinic if you notice signs like these, in line with the clinic's own protocol.

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