Natural substances, such as collagen, elastin and hyaluronic acid that provide the skin with a structure and volume, decrease with the age. This, together with environmental factors, such as exposure to sunlight, smoking and stress, all contribute to how our skin ages. The lips are particularly vulnerable, as they have an extremely thin outer layer, which becomes progressively thinner as the body ages. Over time, the corners of the mouth can begin to droop (mouth frown), the V-shaped area of the upper lip known as the Cupid Bow begins to flatten out and the lips lose their youthful fullness. Vertical lip lines that can cause lipstick bleed may also begin to appear.