Lip "skin" is different.
Why do millions suffer from dry chapped lips each winter? The
reason can be found in the structure of the lips themselves.
The lips' exposed mucous membrane structure is actually different
than other skin. As shown in the diagram to the left, lips
do not have the same protective outer layer, or stratum corneum,
found in other skin; nor do lips have the same complement of oil
and sweat glands. Sweat glands add moisture to skin, but
the lips' only source of moisture is saliva inside the mouth. Thus, harsh winter wind, cold, sun, and dryness--indoors and outdoors--make
lips a vulnerable target for chapping.
