The lips are considered one of the most delicate facial features. Unlike skin, our lips are comprised of the same tissue that can be found on the inside of our mouth. Since the surface of the lips do not have any skin cells, they cannot hold moisture and are susceptible to dehydration. The lips also feature less melanin (the pigment that gives us color) than skin and are at an increased risk of photo aging and sunburn as a result. This destroys the collagen, which is responsible for making the lips look plump. Smoking, repeated sipping, and other lifestyle habits can cause the lips to look even thinner.