Smile lines are facial creases, most often nasolabial folds, that become more visible with expression and changes in skin quality or facial support. They may appear early because of anatomy, genetics, sun exposure and active facial movement. Filler can soften suitable folds, but the amount and placement are individual rather than fixed.
- Smile lines most commonly describe nasolabial folds, which run from the sides of the nose towards the corners of the mouth.
- Genetics, facial movement, skin quality, sun exposure and changes in facial support can all influence how early smile lines become visible.
- Dry or dehydrated skin may accentuate fine lines temporarily, but it does not usually explain established facial folds on its own.
- Filler may soften selected smile lines, although the appropriate amount and placement depend on the individual face rather than a standard formula.
- Botulinum toxin and filler address different features, so treatment planning should consider facial movement, skin quality and structural support.
Smile lines are creases that become more noticeable beside the nose and around the mouth during facial expression. Their depth, the age at which they appear and how they respond to treatment vary widely, because skin quality, facial movement and mid-face support all play a part. Several non-surgical aesthetic options may be considered, but suitability differs from person to person.
What are smile lines?
Smile lines are creases that become more noticeable beside the nose and around the mouth during facial expression. In everyday use, the term most often describes the nasolabial folds, the paired creases that run from the outer edge of each nostril towards the corner of the mouth. Some people also use the same expression for the finer lines that appear on the upper lip or at the edges of the mouth, which are not identical in origin.
These folds are part of normal facial anatomy. They mark the boundary between the cheek and the upper lip region, and they exist in some form at every age, including in children when they laugh. For this reason, their presence alone is not a sign of disease or of premature ageing.
A useful distinction is between lines that appear only with movement and lines that remain visible when the face is relaxed. A crease that deepens during smiling and then settles again tends to reflect muscle action and skin folding. A crease that stays etched at rest usually reflects a combination of skin changes and altered support in the tissues underneath. This difference matters later, because the causes and the options considered are not the same for the two patterns.
Smile lines on the face and around the mouth
On the face, smile lines are most commonly seen in the fold running from the side of the nose to the corner of the mouth. This is the area people point to in a mirror, and it is the region that photographs tend to exaggerate when light falls from above.
Nasolabial folds should not be confused with other creases nearby. Marionette lines extend downwards from the corners of the mouth towards the chin and relate to different tissue dynamics. Fine vertical lines on and around the lips are more superficial and are influenced strongly by skin texture and sun damage. Grouping them together can lead to unrealistic expectations, because each responds differently.
Visibility also fluctuates. Mirror lighting, the intensity of a smile, weight changes and skin dryness can all alter how deep a fold appears on a given day. A line that looks more pronounced in one photograph than another does not, on its own, prove tissue loss. When the mouth corners also sit lower and give a tired or downcast impression, downturned mouth corners may need separate assessment rather than being treated as part of the same fold.
How do smile lines form?
Smile lines form through a combination of repeated facial movement, structural change within the skin and shifting support in the mid-face. No single mechanism explains the pattern in every person, which is why two people of the same age can show very different folds.
Every smile, laugh and spoken sentence moves cheek tissue upwards and inwards against a relatively fixed line near the nose. Over many years, the skin at that boundary folds repeatedly in the same place. At the same time, collagen and elastin content gradually declines, so the skin recovers less readily after each fold and becomes thinner and less resilient. The result is a crease that begins as a movement line and slowly becomes a resting feature.
Changes in facial fat also contribute. Fat in the face is arranged in compartments rather than as a single layer, and the volume and position of these compartments can change with age, weight fluctuation and individual anatomy. Alongside this, the connective tissue that suspends the cheek becomes less supportive. Fat change alone does not cause the fold, but reduced mid-face volume and support can make an existing crease look deeper.
External and inherited factors influence skin ageing more broadly. Cumulative ultraviolet exposure, smoking and genetic predisposition are all associated with earlier loss of skin quality, although their relative weight differs between individuals. Assessment therefore looks beyond the depth of the line itself. Overall facial proportions, the balance between cheek and lip regions and the way the muscles of expression work together all shape how noticeable the fold appears and what, if anything, is appropriate to consider.
Why do smile lines show up early?
Smile lines showing up early cannot be explained by age alone; inherited facial structure, the strength of facial expression and individual skin characteristics all contribute. Some people notice a defined fold in their twenties, while others do not see one until much later.
Thin or sun-affected skin folds more readily and holds a crease for longer. Very expressive faces move the cheek tissue more often and more vigorously. A family tendency towards a prominent fold is common, and the underlying bone and soft tissue arrangement of the mid-face can position the crease more visibly from the outset. Repeated weight gain and loss may also change cheek volume in a way that makes the line more apparent.
Early visibility does not necessarily mean accelerated ageing or an underlying medical problem. In many cases it reflects natural anatomical variation rather than damage.
Skincare is often presented as a solution, but a realistic account is more helpful. Sun protection, gentle daily skin care and avoiding smoking may support skin quality over time, yet their effect on an established structural fold tends to be limited. They are better understood as long-term maintenance than as a way of erasing a crease.
Are smile lines caused by dehydration, fat or braces?
Dehydration, facial fat change and orthodontic treatment influence smile lines to very different degrees: dryness mainly alters surface appearance, shifts in facial fat can genuinely change how deep a fold looks, and braces are not an established direct cause. Each needs to be considered separately rather than lumped together.
Poorly hydrated skin reflects light differently and loses some surface plumpness, which makes fine lines more visible for a time. That surface effect is different from the structural picture behind a nasolabial fold, which relates to repeated movement, skin thickness and the support provided by deeper tissues. Improving hydration may soften the look of fine texture without altering a fold that has formed over many years.
Facial fat plays a role in a different way. Its distribution can shift with age, with weight change or simply because of individual anatomy, and this may influence how prominent the crease looks. The pattern is not the same for everyone, and more volume is not automatically better.
Orthodontic treatment can change the relationship between the teeth and jaws, and any perceived difference in facial appearance needs individual assessment rather than a general assumption.
One caution applies regardless of cause. A facial change that appears suddenly, affects only one side, or comes with pain, numbness or marked swelling should not be assumed to be a cosmetic line and warrants medical assessment.
How much filler do smile lines need?
The amount of filler used for smile lines is not fixed; it is determined at examination according to the depth of the crease, skin quality, mid-face support and the way the face moves. Quoting a standard volume in advance would ignore the variation between individual faces.
Hyaluronic acid filler may be used in suitable cases to soften the appearance of the fold. In some faces the product is placed in or near the crease itself. In others, the more relevant finding is reduced support over the cheek, and treatment is planned to address that structural element rather than the line directly. Assessment of dermal filler treatment considers whether the fold itself or reduced mid-face support is the main feature.
Complete erasure of every line is not always a natural or desirable goal. Overfilling can flatten the normal transition between cheek and lip, alter expression and produce a heavy appearance that is more noticeable than the original crease. For this reason, staged planning with smaller amounts reviewed over time is preferred in some cases.
Risks should be understood before any injectable procedure. Temporary swelling, bruising, tenderness, lumpiness or unevenness are relatively common and usually settle. Less frequently, more serious problems can occur, including vascular compromise in which blood supply to the skin is affected. Increasing pain, pallor or colour change in the skin, or any visual symptom, may require urgent medical assessment rather than waiting.
Other approaches address different layers. Treatments that support skin quality, chemical peeling or energy-based methods may help selected people with superficial lines and texture, though they may not be sufficient alone for a deep anatomical fold. Where there is marked tissue descent and skin laxity, surgical facial rejuvenation is a separate discussion with its own indications and recovery considerations.
Does Botox help smile lines?
Botulinum toxin is not always the primary approach for smile lines, because nasolabial folds relate mainly to volume, tissue support and skin folding rather than to a single overactive muscle. Its role in this specific area is therefore more limited than many people expect.
Botulinum toxin can reduce muscle activity in selected movement-related lines. Around the mouth, however, planning requires particular care, since these muscles contribute to speech, drinking, eating and the shape of a natural smile. Small changes in dose or placement can have a noticeable functional effect.
Outcomes vary with the type of line, the exact area injected, individual muscle patterns and the overall plan, so another person’s experience cannot predict a personal result.
Filler and botulinum toxin are not interchangeable substitutes for one another. Depending on the findings, they may be considered together, used separately, or not considered at all. Possible effects such as altered expression, temporary asymmetry or unwanted changes in mouth function should be discussed in advance.
How long does it take to get rid of smile lines?
How quickly smile lines become less noticeable depends on the approach used, how established the crease is and the individual’s skin and facial anatomy. There is no single timeline that applies to everyone.
Phrases such as “get rid of” and “removal” can suggest total erasure, which is rarely the realistic aim. In aesthetic planning the goal is more often to soften the fold so that it sits in balance with the rest of the face and with natural expression.
After injectable treatment, early swelling or bruising may temporarily change how the area looks, so the immediate appearance is not the settled one. Tissue response and the timing of review differ between individuals.
Skincare, sun protection and lifestyle measures will not remove an existing deep fold quickly, but they can form part of a longer-term approach to supporting skin quality. How long any result lasts also varies, as the product used, the area treated, individual metabolism and facial movement all influence the process.
What can I do about smile lines?
Deciding what to do about smile lines begins with establishing whether the line is superficial, movement-related, or linked to volume and tissue support, since these three patterns lead to different options. Treating all three the same way tends to disappoint.
In broad terms, sun protection and consistent skincare habits target skin quality; filler may address reduced volume or support; selected muscle-focused injections may suit specific movement lines; and surgical options are considered where there is significant laxity and descent. Each addresses a different problem, and none is universally appropriate.
An examination should take account of facial expression, skin quality, previous procedures, current medication and what the person hopes to achieve. For aesthetic assessment, review by a plastic, reconstructive and aesthetic surgeon or another appropriately trained and qualified doctor may be needed.
If a change appears suddenly, affects one side only, or is accompanied by pain, numbness, swelling or altered skin colour, medical help should be sought promptly rather than arranging a routine cosmetic appointment. Suitability for any treatment is determined through examination and facial analysis carried out by Prof. Dr. Şükrü Yazar.
Frequently asked questions
What are smile lines called medically?
Smile lines most often refer to nasolabial folds, the creases running from the sides of the nose towards the corners of the mouth. The term may also be used loosely for other lines around the mouth, which can have different causes and treatment considerations.
Can dehydration cause smile lines?
Dehydration or dry skin can make fine lines look more noticeable temporarily, but it is usually not the sole cause of established nasolabial folds. Facial movement, skin quality and structural support commonly contribute.
Can filler remove smile lines completely?
Filler may soften smile lines in suitable cases, but complete removal is not always a natural or appropriate goal. The amount and placement depend on facial anatomy, the depth of the fold and whether mid-face support is reduced.
Is Botox used for smile lines around the mouth?
Botulinum toxin may be considered for selected muscle-related lines, but it is not routinely the main treatment for nasolabial folds. The mouth area requires careful assessment because its muscles are important for expression and function.
Why do smile lines appear when I am young?
Smile lines can become noticeable at a younger age because of inherited facial anatomy, expressive movement, skin characteristics, sun exposure and changes in facial volume. Their presence does not necessarily indicate a medical problem.
When should smile lines be assessed by a doctor?
An aesthetic assessment can be useful when the lines are a persistent concern or when an injectable procedure is being considered. A sudden one-sided facial change, pain, numbness, swelling or skin colour change needs prompt medical assessment.
