Glossary
What is vermilion border?
Last updated: May 22, 2026
The vermilion border is the boundary line between the vermilion (colored part of the lip) and the surrounding facial skin. A sharp, well-defined vermilion border is a marker of facial youth. Border definition naturally decreases with age as collagen and orbicularis oris muscle tone diminish, which is why older faces often benefit from procedures restoring border definition rather than just adding lip volume.
How vermilion border is measured
Assessed visually for clarity and sharpness of the border line. Computer vision can quantify border sharpness as gradient strength at the lip-skin boundary. The vermilion border is bilaterally symmetric in healthy faces.
Why vermilion border matters
Vermilion border definition is one of the earliest visible markers of perioral aging. Loss of border definition contributes to the 'aging lip' appearance often addressed with cosmetic injections. The correct intervention for border loss is border-definition filler (low volume, placed at the border), not bulk lip volume filler.
Normal range
Sharp, well-defined border with bilateral symmetry. Aging-related softening typically becomes noticeable in the 40s and accelerates with smoking and UV exposure.
Source: Standard aesthetic dermatology
How Facet uses vermilion border
Facet's lip module scores vermilion border definition from a front-facing photo. Higher border definition produces higher module scores.
Frequently asked
Is lip filler always good for older faces?+
Volume filler alone often makes older lips look puffy without addressing the actual aesthetic issue (border softening). The correct intervention for older faces is border-definition filler, which uses low-volume placement along the vermilion border line.
What ages the vermilion border?+
Loss of collagen, decreased orbicularis oris muscle tone, UV exposure, smoking, and habitual lip-pursing all degrade vermilion border definition over time. Sun protection and avoiding smoking are the most impactful preventive interventions.