Skin Care Education

Smile Lines

The folds of skin running from the sides of the nose to the corners of the mouth. Also known as laugh lines or nasolabial folds. A normal facial feature in all adults that deepens progressively with midface ageing.

What Are Smile Lines?

Smile lines is one of the most widely used everyday terms for the nasolabial folds: the natural folds of skin and soft tissue that run from the sides of the nose downward to the corners of the mouth. They are also commonly referred to as laugh lines. All three terms, smile lines, laugh lines, and nasolabial folds, describe exactly the same anatomical structure from different linguistic perspectives.

Smile lines are a completely normal and universal feature of the adult face. They are present to some degree in virtually every adult and become most visible during smiling and other expressions involving the cheeks and midface muscles, which is the origin of the colloquial name. In younger individuals with full, supported cheeks and firm elastic skin, the folds are typically mild and resolve substantially when the face returns to rest. With age, they deepen and become more prominently visible even at rest as the structural changes of midface ageing accumulate.

Despite their name, the primary cause of smile lines deepening with age is not the act of smiling but the loss of volume in the midface and cheeks that is a normal part of facial ageing. As the fat pads of the midface reduce over time, the overlying tissue loses its internal support and descends under gravity, pushing into and deepening the nasolabial fold from above. This means that smile lines deepen as a consequence of structural ageing across the whole midface rather than as a direct result of expressive activity.

Causes and Contributing Factors

Factor	Description
Midface volume loss	The primary driver of smile line deepening. The fat pads distributed throughout the cheeks and midface reduce progressively from the 30s onward. As this volume decreases, the skin and soft tissue above loses its internal scaffold and descends under gravity, accumulating in and progressively deepening the nasolabial fold from above.
Loss of skin elasticity	Progressive decline in collagen and elastin reduces the skin’s ability to maintain its position and resist the effects of gravity and tissue descent. Reduced skin elasticity allows the fold to deepen more readily and to become more permanently established in the skin surface.
Facial bone remodelling	The underlying bony architecture of the midface undergoes gradual remodelling with age. Reduction in midface bone volume and projection diminishes the structural support for the overlying soft tissue, contributing to tissue descent and fold deepening.
Retaining ligament laxity	The zygomatic and masseteric retaining ligaments that anchor the cheek tissue to the facial skeleton gradually lengthen and weaken with age, allowing the cheek tissue to descend more freely and contributing to the deepening of the smile line fold.
Repeated facial expression	Smiling and laughing repeatedly compress the tissue adjacent to the nasolabial fold. Over many years and thousands of repetitions, this mechanical contribution adds to the permanence of the crease, though it is a secondary factor compared to the structural volume and support changes.
Weight loss	Any significant reduction in facial fat removes the volume that was previously supporting and softening the nasolabial fold, making previously mild smile lines more pronounced.
Genetics	Facial anatomy, fat distribution patterns, skin ageing characteristics, and the rate of midface volume loss are all significantly influenced by genetics. Some individuals have naturally deeper nasolabial folds from early adulthood due to inherited facial structure.

Frequently Asked Questions: Smile Lines

Yes. All three terms refer to the same anatomical feature: the folds of skin and soft tissue running from the sides of the nose downward to the corners of the mouth. Nasolabial folds is the precise anatomical and clinical term. Smile lines and laugh lines are the more widely used colloquial terms that describe the same structure by reference to the expressions during which they are most visible. The choice of term is simply a matter of context and register, with all three being completely interchangeable in meaning.

No, at least not in any meaningful sense. While smiling does involve repeated compression of the tissue alongside the nasolabial fold and contributes incrementally over a lifetime of expression, the primary driver of smile line deepening is not facial expressiveness but the structural changes of midface ageing, particularly volume loss. The nasolabial folds deepen in people who rarely smile just as they do in highly expressive individuals, because the dominant mechanism is tissue descent from above rather than expression-driven crease formation from below. There is no evidence that reducing smiling would meaningfully slow the development of smile lines.

Most people notice that their smile lines are becoming visible at rest, rather than only during expression, from their late 30s to mid-40s onward, though the timing varies considerably. Those with naturally slender faces, a history of significant weight loss, prominent UV exposure, or a family pattern of early midface volume loss may notice changes earlier. Those with fuller cheeks, naturally thicker skin, and good sun protection habits may find that their smile lines remain relatively mild at rest into their 50s.

Yes. Some individuals have naturally deep nasolabial folds from early adulthood due to their inherited facial anatomy, particularly the depth of the nasolabial groove, the prominence of their cheekbones relative to the adjacent soft tissue, or a naturally more angular facial structure. In these cases the fold is an anatomical characteristic rather than a sign of premature ageing. Smile lines that are visible and prominent in a young person with good overall skin quality and full facial volume are typically a structural feature rather than an ageing concern.