Smile Lines: What Causes Nasolabial Folds and How to Actually Treat Them

Everyone who has ever smiled has smile lines — the parentheses that bracket the mouth, running from the sides of the nose to the corners of the lips. Dermatologists call them nasolabial folds, and they are among the earliest and most visible signs of facial aging.

Here is what most skincare content gets wrong: smile lines are not simply wrinkles. They are architectural features of the face — part structural, part muscular, part gravitational. Understanding why a crease that once disappeared at rest eventually stays is the key to choosing treatments that actually work.

The Anatomy of Smile Lines

The nasolabial fold is not a wrinkle in the traditional sense. It is a junction between two tissue compartments of the face — like the seam where two tectonic plates meet. On one side sits the cheek, supported by deep fat pads and anchored to bone. On the other sits the upper lip, thinner and more mobile.

In youth, this junction is soft and shallow. What changes over time is not just the skin but the entire scaffolding beneath it.

Pessa and colleagues demonstrated that the maxillary bone — the platform supporting the midface — actually recedes with age [1]. Your cheek’s foundation is literally shrinking. Simultaneously, the malar fat pads descend under gravity, increasing tissue bulk above the fold while structural support beneath it erodes.

Collagen Loss: The Accelerant

If bone resorption and fat descent set the stage, collagen loss is the accelerant. After age 20, the skin loses roughly 1% of its collagen per year [3]. Varani et al. measured actual collagen production rates in aged versus young skin and found significant decreases in synthesis precursors.

Quan et al. showed that aged skin has reduced expression of connective tissue growth factor (CTGF/CCN2), a signaling molecule essential for collagen production [2]. Without adequate CTGF, fibroblasts do not receive the signal to produce collagen. The factory is still there, but the work orders have stopped coming in.

This collagen deficit makes the skin thinner, less elastic, and less capable of resisting the mechanical forces that create folds. A young face with abundant collagen can bounce back from repeated smiling. An aging face with diminished collagen cannot — the crease becomes permanent.

Dynamic vs. Static Lines: Why the Distinction Matters

Understanding this distinction is critical for choosing the right treatment approach.

Understanding why a crease that once disappeared at rest eventually stays is the key to choosing treatments that actually work.

Dynamic smile lines appear only during expression and disappear at rest. They are driven by the zygomaticus major and levator labii muscles pulling cheek tissue upward. In younger skin with robust collagen, the tissue springs back between expressions.

Static smile lines are visible even at rest — a permanent structural change from years of repetitive movement combined with progressive collagen, elastin, and volume loss.

Most people over 35 have some degree of static nasolabial folding. The goal of treatment is not to eliminate a natural anatomical feature but to soften static depth and improve skin quality in the area.

Topical Treatments That Have Evidence

No topical product will restore lost bone volume or reposition descended fat pads. That is the honest truth, and anyone claiming otherwise is selling fiction. What topicals can do is improve the skin itself — its thickness, its collagen density, its texture — which softens the appearance of the fold.

Retinoids remain the most evidence-supported topical option. Mukherjee et al. reviewed decades of clinical data and confirmed that retinoids stimulate collagen synthesis, increase epidermal thickness, and improve skin texture with consistent use [4]. For smile lines specifically, retinol works by rebuilding the dermal matrix that has thinned with age. The fold does not disappear, but the skin over it becomes thicker and more resilient, which visually reduces its depth.

The key consideration with retinol around the nasolabial area is that this skin is relatively thin and prone to irritation. Starting with a lower concentration and using formulations designed for sensitive skin is practical advice, not marketing language.

Vitamin C (L-ascorbic acid) functions as a cofactor in collagen synthesis and provides antioxidant protection against UV-induced collagen degradation. Used alongside retinol, it addresses collagen loss from two angles — stimulating new production and protecting existing structures. Baumann’s comprehensive review of skin aging treatments supports the use of antioxidant-based topicals as part of a multi-pronged approach [6].

Peptides are signaling molecules that prompt fibroblasts to increase collagen output. The evidence base is less robust than for retinoids, but certain peptides (palmitoyl pentapeptide-4, copper peptides) have shown measurable effects on skin firmness.

Hyaluronic acid in topical form provides surface hydration and plumping. Bukhari et al. found consistent evidence for improved skin hydration and elasticity [5]. It will not restructure a deep nasolabial fold, but it contributes to overall skin quality and complements active ingredients like retinol.

The key consideration with retinol around the nasolabial area is that this skin is relatively thin and prone to irritation.

Professional Treatments: A Realistic Overview

When topical treatments have reached their ceiling, professional interventions address the structural components that creams cannot.

Hyaluronic acid dermal fillers are the most common professional treatment for nasolabial folds. Injected directly into or beneath the fold, they restore lost volume and physically lift the crease. Results are immediate and typically last 6 to 18 months. This is currently the most effective single intervention for moderate to deep static folds.

Microneedling creates controlled micro-injuries that trigger the wound-healing cascade, increasing collagen and elastin production. It is particularly effective for improving overall skin quality in the midface area.

Energy-based devices (radiofrequency, ultrasound) deliver heat to the deep dermis, causing collagen contraction and stimulating new formation. Best suited for mild to moderate laxity as maintenance rather than primary treatment for deep folds. Medium-depth chemical peels can also stimulate collagen remodeling in the area.

Building a Practical Strategy

The most effective approach to smile lines combines daily topical care with realistic expectations about what each intervention level can achieve.

Start with the foundation: a retinoid applied consistently at night, paired with daily broad-spectrum sunscreen. Sunscreen is not optional — UV exposure accelerates every mechanism that deepens nasolabial folds, from collagen destruction to elastin degradation. Understanding the relationship between sun damage and skin aging is fundamental to any anti-aging strategy.

Layer in supportive ingredients: vitamin C in the morning for antioxidant protection and collagen cofactor support, hyaluronic acid for hydration, and peptides if your budget allows.

For those seeking enhanced retinol delivery with reduced irritation, encapsulated formulations — including Nanoretinol® from North Biomedical® — use lipid nanoparticle technology to deliver retinol more efficiently to the dermis while minimizing surface irritation. This is particularly relevant for the thinner, more sensitive skin of the nasolabial area.

If static folds are moderate to deep and topical improvements have plateaued, consult a board-certified dermatologist or plastic surgeon about fillers or energy-based devices. The best outcomes typically combine professional treatments with a disciplined daily topical regimen.

What You Can Realistically Expect

Smile lines will not vanish — nor should they. They are part of the architecture of a face that has expressed emotion for decades. The realistic goal is to slow their progression, improve skin quality in the area, and reduce static depth when desired.

Consistency matters more than intensity. A moderate retinoid used every night for a year will outperform a high-concentration product used sporadically. Your smile lines are evidence that you have lived a life worth smiling about. The science simply gives you tools to keep the skin around them as healthy as possible.

References

1. Pessa JE, Zadoo VP, Mutimer KL, et al. “Relative maxillary retrusion as a natural consequence of aging: combining skeletal and soft-tissue changes into an integrated model of midfacial aging.” Plastic and Reconstructive Surgery. 1998;102(1):205-212. doi:10.1097/00006534-199807000-00030

2. Quan T, Shao Y, He T, Voorhees JJ, Fisher GJ. “Reduced expression of connective tissue growth factor (CTGF/CCN2) mediates collagen loss in chronologically aged human skin.” Journal of Investigative Dermatology. 2010;130(2):415-424. doi:10.1038/jid.2009.224

3. Varani J, Dame MK, Rittie L, et al. “Decreased collagen production in chronologically aged skin.” American Journal of Pathology. 2006;168(6):1861-1868. doi:10.2353/ajpath.2006.051302

4. Mukherjee S, Date A, Patravale V, et al. “Retinoids in the treatment of skin aging: an overview of clinical efficacy and safety.” Clinical Interventions in Aging. 2006;1(4):327-348. doi:10.2147/ciia.2006.1.4.327

5. Bukhari SNA, Roswandi NL, Waqas M, et al. “Hyaluronic acid, a promising skin rejuvenating biomedicine: A review of recent updates and pre-clinical and clinical investigations on cosmetic and nutricosmetic effects.” International Journal of Biological Macromolecules. 2018;120(Pt B):1682-1695. doi:10.1016/j.ijbiomac.2018.09.188

6. Baumann L. “Skin ageing and its treatment.” Journal of Pathology. 2007;211(2):241-251. doi:10.1002/path.2098