Smile Lines (Nasolabial Folds): Why They Deepen and What Helps

Smile lines, or nasolabial folds, are the creases that run from the sides of your nose to the corners of your mouth. Everyone has them, because they mark a natural boundary between cheek fat and the skin around the mouth. They deepen with age mainly as cheek volume shifts and descends, with sun damage and weight change adding to it. Creams help the skin; fillers address volume.

Below we explain where these folds come from, why smiling gets more blame than it deserves, what a realistic at-home routine can do, and what the in-office options cost you in time, money and risk.

What are smile lines?

Smile lines are the two diagonal folds that frame the mouth, from the edge of each nostril down toward the lip corners. Doctors call them nasolabial folds. They're different from the fine vertical lines on the lips, and from marionette lines, which run down from the corners of the mouth toward the chin.

The fold isn't a flaw in the skin. In a dissection study of facial anatomy, plastic surgeons found that the nasolabial fold is a discrete unit with distinct anatomical boundaries, one of several separate fat compartments in the face. What changes with age is how much the cheek above it overhangs, and how deep a shadow that casts.

Why do smile lines get deeper with age?

They deepen mostly because of what happens underneath the skin. The same anatomy study concluded that facial aging is, in part, characterized by how these compartments change with age, and that the face does not age as a confluent or composite mass. As the cheek compartments lose fullness and sit lower, more tissue rests against the fold, and the crease looks heavier.

Sagging is mostly driven by time. In a study of 298 Caucasian women aged 30 to 78 that compared sun-seekers with people who avoided sun, signs of sagging (ptosis) were linked more to chronological aging and did not differ between the two groups. Wrinkles and skin texture, by contrast, were affected by both sun and age. That split matters: sun protection has a big effect on the skin of the fold, and a smaller one on the sag that creates it.

Does smiling cause smile lines?

Smiling makes the fold visible, but it isn't the main reason the fold deepens. Repeated expressions do etch some lines into skin, and the AAD notes that repeatedly contracting the same facial muscles for years can make lines permanent. That matters most for forehead lines and crow's feet. The depth of a nasolabial fold at rest, though, depends far more on the volume and position of the cheek tissue above it. Please don't stop smiling to protect your face. It wouldn't work, and it isn't worth it.

Is it normal to have smile lines in your 20s?

Yes. Because the fold is part of normal facial anatomy, almost everyone has a visible nasolabial crease when they smile, and many people have a soft one at rest. How visible they are at that age mostly reflects the shape of your face and cheeks, and a recent change in weight can play a part too. If you also have forehead lines you're watching, see forehead lines in your 20s.

Does weight change affect smile lines?

It can, and in both directions depending on age. In a study of 186 pairs of identical twins, a four-point higher body mass index was linked to an older appearance in twins younger than 40 but a younger appearance after age 40. One reading of that result is that facial fullness can soften folds in later decades, which is why a large weight loss may leave them looking deeper. If you're losing weight for health reasons, that's worth doing; just expect the face to change shape, and know that the in-office options below exist if it bothers you.

How can you reduce smile lines at home?

At-home care improves the quality of the skin along the fold and slows further damage. It can't replace lost volume. Be wary of any cream promising to "fill" nasolabial folds.

1. Daily broad-spectrum sunscreen, SPF 30 or higher. This is the AAD's first recommendation for reducing premature skin aging. In a randomized trial of 903 adults under 55, the daily sunscreen group showed no detectable increase in skin aging after 4.5 years.
2. A retinoid at night. The AAD says retinoids improve skin tone and reduce fine lines and wrinkles. Start with a gentle formula every other night and build up. The AAD also says retinoids should not be used during pregnancy.
3. Moisturizer. The AAD notes that moisturizing traps water in the skin, which can help reduce the appearance of some fine lines around the fold.
4. Quit smoking. The AAD says smoking greatly speeds up how quickly skin ages.
5. Realistic timing. Most products take at least six weeks to work, according to the AAD. Expect smoother skin along the fold; its depth won't change much.

Facial yoga, face rollers and gua sha are popular for smile lines. We didn't find good evidence in the sources we reviewed that any of them reduce fold depth, so enjoy them if you like the ritual, and keep expectations low.

What in-office treatments help smile lines?

Dermal fillers are the most common treatment, and the FDA states that absorbable fillers are approved for moderate to severe facial wrinkles and skin folds, such as nasolabial folds. Treatment plans may add volume to the cheeks as well as the fold itself, since the AAD describes fillers as able to restore fullness to cheeks, hollow areas under the eyes, and deep creases.

The AAD notes that dermatologists often use more than one type of treatment for aging skin, so a plan may combine cheek filler with resurfacing, for example.

Are fillers for smile lines safe?

Most filler side effects are mild and temporary, but fillers carry real risks. The FDA says the most concerning risk is unintentional injection into a blood vessel, which can lead to tissue death, vision abnormalities including blindness, and stroke. The agency also warns that needle-free devices are not approved by the FDA for filler injection and that people shouldn't buy fillers online. The AAD recommends a doctor who has expertise injecting fillers and says serious side effects are more likely when the injector lacks adequate medical training and experience. Ask who will inject you, what product they're using, and how they handle complications before you book.

For the related problem lower on the face, see our guide to sagging jowls and jawline, and for the difference between surface lines and deeper folds, fine lines vs wrinkles.

How can a selfie scan help you track smile lines?

Changes around the mouth are slow and lighting-dependent: overhead light deepens every shadow, and a smile changes the fold completely. A consistent photo record makes comparisons fairer. Pori takes a selfie, maps the face with a 468-point mesh and reads each region with an AI vision model, giving an overall skin score from 0 to 100 plus a breakdown that includes Anti-aging & Elasticity, and a skin-age estimate. Before-and-after comparisons and progress charts help you judge whether a retinoid habit or a treatment changed the skin over months. Pori is a free download with a free first scan; Pro costs $9.99 a week or $49.99 a year in the US as of October 2026.

Scan with a relaxed mouth, in the same light and at the same distance each time. Read more on what skin age means. An app tracks how your skin looks and is not a diagnosis, so bring anything new, sore or changing to a dermatologist.