"I've had lip filler and chin filler, but somehow my side profile looks unnatural." We hear this from time to time in clinic, and some patients say their lips and chin look as if they do not belong together. If the balance looks off even though the filler has gone in where it should, we need to look at a spot that is easy to miss while the focus is on the lips and the chin. It is the hollow groove between the lips and the chin, the labiomental crease. This article covers why that groove looks deeper, and what we look at together when planning filler.
Three-Line Summary
- When the lips and the chin come forward, the hollow between them can look relatively sunken, and the shadow can look deeper. This area is the labiomental crease, and what matters here is connecting rather than filling.
- The labiomental crease is not just a mark where the skin has folded; it is an anatomical boundary where muscle and skin are firmly joined. It can stand out more when changes in bony support, loss of volume in the deep layers and weakening of the retaining ligaments overlap with age.
- When planning filler, we look together at properties with supporting strength, at depth and cannula use with the blood vessels in mind, and at the connection with the lips and the chin. Even with a cannula, the risk of vascular occlusion is not zero, and there is no single correct volume.
Why Filling Just the Lips and Chin Can Look More Awkward — The Shadow Effect
The lips and the chin are areas where filler is widely used to enhance volume. But there is one catch here. When the lips, above, come forward and the chin, below, comes forward as well, the hollow between them can look relatively sunken, and under lighting the shadow can look deeper. This is what patients mean when they talk about a shadow under the lip.
It is like a valley looking deeper and darker when high mountains rise on either side of it. This phenomenon is sometimes called the shadow effect.
What Looks Different When the Shadow Darkens
- The line running from the lips to the chin can look abruptly broken.
- The chin can look as if it projects more than it actually does. This is the impression people often describe as looking like a protruding lower jaw.
- The face can come across as somewhat stubborn, or as older.
So what matters in this area is not filling but connecting. It is not just the volume of the lips and the chin: the line that joins them also has to be natural for the profile to look natural.
The Labiomental Crease Is an Anatomical Boundary, Not a Simple Wrinkle
The labiomental crease is also called the chin crease, and it goes by the names mentolabial fold and mentolabial sulcus as well. This area is not simply a place where the skin has folded. It is a boundary where muscle and skin are quite firmly connected, and structurally it acts largely as a fixed point.
Where Muscle Connects Directly to the Skin
The muscles of facial expression, such as the muscles around the mouth and the muscles of the chin, often connect directly to the skin (the dermis), and this kind of connection between muscle and skin can create particular lines. The labiomental crease corresponds to the boundary where the orbicularis oris, the muscle around the mouth, meets the mentalis, the muscle of the chin.
The study that Zhang and colleagues published in Aesthetic Plastic Surgery in 2025 is an anatomical study that used micro-CT to examine one of the folds of the lower face: the fold that runs from the corner of the mouth down toward the chin (the labiomandibular fold, commonly called the marionette line). Although it did not deal directly with the labiomental crease, the study reported that the muscles of facial expression connect vertically to the dermis and pull on the skin through a structure in which collagen, elastin and muscle are densely interwoven, and that this is involved in fold formation. In the labiomental crease as well, this kind of connection between muscle and skin can act to keep the groove fixed in one place.
The Difference Between Just Below the Lip and Farther Down
In the zone just below the lip, the fibrous supporting structures are firmly anchored, while farther down they are woven a little more loosely. This difference affects where the crease folds and how deep it is. This is what it means to say that the labiomental crease is not just a mark where the skin has folded but a boundary created by structure, and it is why treatment in this area has to be based on an accurate knowledge of the anatomy.
Three Reasons the Labiomental Crease Stands Out More
The labiomental crease can become more noticeable with age, or after treatment to the lips and the chin. Three changes are involved here.
Changes in Bony Support
With age, the facial bones do not change evenly as a whole; rather, they show a pattern in which support weakens in particular zones. These changes can make the contour of the lower face and the boundaries of its creases stand out more.
Loss of Volume in the Deep Layers
It is not just the volume visible from the outside that decreases. In the face, emphasis is being placed on the view that loss of volume in the deep layers, that is, the deep fat and the supporting layers, can come first or can have the greater effect. When support in the deep layers decreases, the surface looks as if it has sunk (pseudoptosis), and as a result the boundary between the lips and the chin tends to look sharper.
In particular, changes in the deep structures around the mouth and around the chin are discussed as a factor that makes the labiomental crease stand out. We have set out the process by which boundaries come to stand out as deep-layer volume decreases, using the midface as the example, in our article on anterior cheek volume loss.
Weakening of the Retaining Ligaments and Fibrous Septa, and the Chin Muscle
When the retaining ligaments and fibrous septa weaken in the course of aging, the boundary around the fixed point can be accentuated further. In addition, when the mentalis is strong or overactive, movement and the fixed point overlap, and the line can look deeper. In such cases, botulinum toxin sometimes helps in a supporting role.
Three Things We Look at When Planning Filler — Starting With Properties
The purpose of using hyaluronic acid filler in the labiomental crease is to fill the deep groove between the lips and the chin, so that the line from the lips down to the chin continues without a break. We check three things at this point. They are the properties of the filler, the depth and method of injection, and the connection with the lips and the chin.
Properties That Suit This Area — Support and Elasticity
The labiomental crease is an area that moves, and its tissue is on the firm side. So if only an overly soft filler is used, the following can happen.
- The line that has been connected can collapse quickly.
- The surface can feel bumpy.
- It can feel as though the result does not last long.
So this zone is usually planned around supporting strength, that is, the strength to hold a shape. That means having a filler that gives good support and has high elasticity (G') act as a framework, or giving firm support to the area of the deep crease. The specific choice, though, depends on skin thickness, the depth of the crease and movement.
Depth Planning and the Cannula — Taking the Blood Vessels Into Account
Blood vessels run through this area as well, and their course varies quite a bit. Anatomical studies emphasize that the course of the vessels around the lower lip and the lower face is varied, and emphasize an approach that keeps to a relatively safe plane (the plane of safety) in order to reduce risk.
Why the Cannula Is Preferred
In comparisons based on large-scale reports, there are data in which vascular occlusion was reported less often with cannulas than with needles. However, using a cannula does not bring the risk down to zero. There is a trend toward preferring the cannula, weighing the aim of shaping a wide area smoothly together with the safety aspect.
Which Layer, by What Method, and How Slowly
What decides both the result and safety is which layer the filler is injected into, by what method, and how slowly. Considering the blood vessels alone, injecting into a superficial layer would be the right approach. But if the filler goes into a superficial layer alone, it lasts a very short time and moves easily. So we inject across several layers with a cannula, while taking care over safety.
Because blood vessels run through this area, we do not use a needle in the labiomental crease. This is because injecting into a deep layer with a needle can put the blood vessels at risk. In the lips and the chin, though, we use a needle as well, to add subtle volume. For the anatomy around the lower lip and for injection safety, we referred to the article that Swancutt and colleagues published in the Journal of Clinical Medicine in 2025.
We Look at the Lips, the Chin and the Labiomental Crease as One Set
The labiomental crease can improve even when it is filled on its own. In many cases, though, the lips, the lower lip in particular, and the chin have to be looked at together for the lines of the profile to flow naturally.
There Is No Single Correct Volume
There is no set answer to the question of how many cc is correct. That is because it depends on facial structure, skin thickness and movement. What to look at before volume is a plan that creates a sense of continuity without overcorrection.
How It Relates to the Lines at the Corners of the Mouth
When this area is sunken, the lines at the corners of the mouth (marionette lines) can also look more prominent. We cover marionette lines and the sagging around them separately in our article on deep-cheek sagging and jowls.
What to Know Before Treatment
- Safety principles — with filler in any area, what matters is an understanding of the anatomy, the depth of injection, injecting slowly and in small amounts, and being ready to respond to an emergency. Blood vessels run through this area too, and even when a cannula is used, the risk of vascular occlusion does not drop to zero.
- Individual variation — the type and volume of filler, and the layer it is injected into, depend on facial structure, skin thickness, the depth of the crease and movement. This article is a general explanation and does not replace an individual diagnosis. Please decide on treatment after a thorough consultation.
References
- Zhang M, Sun Y, Zhang Y, Dong R, Jin L, Chen Z, Yu N, Huang J, Long X. The Labiomandibular Fold Anatomy for Comprehensive Lower Facial Rejuvenation: A Micro-Computed Tomography Investigation. Aesthetic Plast Surg. 2025;49(11):2905-2914.
- Swancutt MM, Allard AJ, Ho A, Sloan S. Filling the Gap: Facial Anatomy and Safe Lower Lip Injection Practices. J Clin Med. 2025;14(9):3214. doi:10.3390/jcm14093214
From Consultation Through Treatment
A board-certified dermatologist examines you directly, identifies which layer the cause sits in, sets the device and the parameters, and then carries out the procedure as the same physician. This is not a structure in which a consultant sells the treatment.
The number of sessions, the intervals, the maintenance point and the cost are agreed together before the first session.
Frequently Asked Questions
- I had lip filler and chin filler, so why does the shadow under my lip look darker?
- When the lips and the chin come forward, the hollow between them can look relatively sunken, and under lighting the shadow can look deeper. It is like a valley looking deeper when mountains rise on either side of it, which is why it is sometimes called the shadow effect. Even when the filler has gone in where it should, it can look this way if the two areas are not joined up in between.
- How is the labiomental crease different from an ordinary wrinkle?
- It is not just a mark where the skin has folded; it is an anatomical boundary where muscle and skin are firmly connected. It is where the orbicularis oris, the muscle around the mouth, meets the mentalis, the muscle of the chin, and structurally it acts largely as a fixed point. That is why it is an area that has to be treated with an accurate knowledge of the anatomy.
- Why does the labiomental crease look deeper with age?
- Three changes can overlap. Support from the facial bones weakens in particular zones, volume in the deep layers decreases so that the surface looks as if it has sunk, and the retaining ligaments and fibrous septa weaken. On top of this, if the mentalis, the chin muscle, is strong or overactive, the line can look deeper.
- Is it enough to fill just the labiomental crease?
- Filling it on its own can bring improvement. In many cases, though, the lips, the lower lip in particular, and the chin need to be looked at together for the lines of the profile to flow naturally. So we plan the three areas as one set.
- How many cc of filler do I need?
- There is no single correct volume. That is because it depends on facial structure, skin thickness and movement. More important than volume is a plan that creates a sense of continuity from the lips to the chin without overcorrection.
- What properties does a filler for the labiomental crease need?
- The labiomental crease moves and its tissue is on the firm side, so if only an overly soft filler is used, the line can collapse quickly, the surface can feel bumpy, or it can feel as though the result does not last long. So we choose with supporting strength in mind, that is, the filler's support and elasticity. The specific choice depends on skin thickness, the depth of the crease and movement.
- Is filler treatment in this area risky?
- With filler in any area, safety principles matter, such as understanding the anatomy, the depth of injection, injecting slowly and in small amounts, and being ready to respond to an emergency. Blood vessels run through this area too, and their course varies. There are data in which vascular occlusion was reported less often with cannulas than with needles, but the risk does not drop to zero.
- Is the treatment done with a cannula or a needle?
- Because blood vessels run through this area, we do not use a needle in the labiomental crease; we inject across several layers with a cannula. This is because filler placed in a superficial layer alone lasts a very short time and moves easily. In the lips and the chin, we use a needle as well, to add subtle volume.
- Are there cases where botulinum toxin helps?
- If the mentalis, the chin muscle, is strong or overactive, movement and the fixed point overlap, and the line can look deeper. In such cases botulinum toxin sometimes helps in a supporting role. Its role, though, is strictly a supporting one.