The cuticle of both lips is not only thin, but also the granular layer is thin, so the granules and melanin in the granular layer have disappeared, so that the capillaries of dermal papilla appear dialysis red, and the lips appear ruddy.

Compared with the skin, the cuticle of the lips is very thin, and the water is easy to evaporate. Besides, it has poor physical irritation, is easy to be injured, and almost has no sebum film. Because it is dry and easy to become rough, it is a sensitive part that needs careful care.