By LIV Clinic · Medically reviewed by Dr. Narathai Vichienkalayarut, M.D. · Published September 30, 2026

The most common mistake with smile lines is treating the line instead of the reason it appeared.

What is the best injectable for smile lines? Dermal filler is the usual answer, but the best approach often means restoring cheek volume rather than filling the fold directly — because nasolabial folds are usually caused by mid-face volume loss, and overfilling the fold itself looks heavy and unnatural.

Why smile lines form

Not just from smiling

Nasolabial folds run from the nose to the mouth corners. Everyone has them when smiling; the concern is when they become visible at rest.

The real cause is usually above

As mid-face volume declines, the cheek descends slightly and the tissue folds over — so the fold deepens because of what happened above it.

• Loss of mid-face and cheek volume
• Descent of tissue over the fold
• Thinning, sun-damaged skin making the crease sharper
• Repeated smiling over decades
• Genetics and natural facial structure

Why treating the fold directly often fails

It can look heavy

Injecting large volumes straight into the fold can create a thick, unnatural ridge rather than a smoother transition.

It ignores the cause

If the cheek has deflated, filling the fold treats the symptom while the underlying support stays missing.

The better approach: support the cheek

Lift from above

Restoring cheek volume with structural filler re-supports the mid-face, which softens the fold indirectly and looks considerably more natural.

Then refine if needed

A small amount of softer filler can be placed in the fold afterwards for refinement — but far less than if it were treated alone.

Which products suit

See our guide to choosing cheek filler.

Where biostimulators fit

A gradual alternative

Biostimulators rebuild mid-face volume over months, which softens folds very naturally without placed gel.

Choosing between them

Filler gives an immediate, reversible result; a biostimulator gives a slower, diffuse one — see how to choose between them.

What about Botox?

Not the right tool here

Nasolabial folds are caused by volume loss and descent rather than muscle movement, so Botox is not a primary treatment for them.

Where it helps nearby

Botox can soften a gummy smile or downturned mouth corners, which are different concerns often mentioned alongside smile lines.

Realistic expectations

Softened, not erased

The goal is a smoother transition and a less tired appearance, not eliminating a natural facial contour entirely.

Skin quality matters too

Sun damage and thin skin make folds look sharper, so skin treatment often improves the overall result.

How to approach smile lines

A practical sequence:

1. Have a consultation assessing your mid-face, not just the fold.
2. Ask whether cheek support would soften the fold indirectly.
3. Start conservatively rather than filling the fold heavily.
4. Consider a biostimulator if you prefer a gradual change.
5. Allow about two weeks for filler to settle before judging.
6. Address skin quality and sun protection alongside.

Smile line treatment at LIV Clinic Koh Samui

At LIV Clinic, Dr. Narathai assesses the cause before treating the fold, using filler and biostimulators as appropriate. Book a consultation.

Frequently asked questions

Safety and consultation

Smile line treatment is a medical procedure and, like any injectable treatment, carries some risk — common temporary effects can include redness, swelling, bruising or tenderness, and less common reactions are possible. Results vary from person to person, and no specific outcome can be promised. This article is general information, not medical advice.

At LIV Clinic, every treatment begins with an in-person assessment by Dr. Narathai Vichienkalayarut, M.D., who reviews your skin, medical history and goals before recommending a personalized plan. Book a consultation to find out whether this treatment suits you.