What Causes Laugh Lines

What Causes Laugh Lines

Laugh lines, also called nasolabial folds or smile lines, form primarily from repeated facial movements over time. Every smile, squint, and laugh creases the skin around the mouth and eyes, and as the skin loses its ability to spring back fully, those creases deepen into visible lines.

Repetitive Muscle Movement

The core mechanical cause is the contraction of facial muscles. When you smile, the zygomaticus major muscle pulls the corners of your mouth upward, while muscles around the eyes contract during a genuine grin. Over decades, the skin folds along these pathways repeatedly. The epidermis remembers these expressions, and the dermal support structure gradually weakens, making the lines more permanent even at rest.

Loss of Collagen and Elastin

Collagen and elastin are the proteins that keep skin firm and resilient. Starting in the mid-20s, collagen production declines by roughly one percent per year. Elastin fibers also lose their snap, so the skin cannot rebound after a facial expression as it once did. This structural thinning is why laugh lines deepen with age, even in people who smile just as frequently.

Sun Damage and Photoaging

Ultraviolet radiation breaks down collagen and elastin in a process called photoaging. The skin around the mouth and eyes has relatively thin protection and is often exposed to sunlight. Cumulative UV exposure accelerates the degradation of connective tissue, making laugh lines appear earlier and more deeply than they otherwise would.

Other Contributing Factors

• Genetics: Skin thickness and natural collagen density are inherited, which is why some people develop prominent laugh lines earlier than others.
• Smoking: The repetitive puckering motion and oxidative stress from tobacco smoke damage collagen and accelerate wrinkle formation.
• Weight Fluctuations: Gaining and losing weight can stretch and weaken the skin's supportive structure around the mouth.
• Sleep Position: Consistent pressure from sleeping on the face can crease the skin over time.

Can Laugh Lines Be Prevented

While you cannot stop facial expressions, sun protection, moisturizers that support barrier function, and avoiding smoking can slow their deepening. Some people turn to dermal fillers or retinoids to soften existing lines, but the underlying movement and aging process remains the root cause.