Dry and Chapped Lips

Lip "skin" is very unique. It consists primarily of mucous membrane, which has fewer and different glands than ordinary skin. The lip is also unlike other skin in that the outer layer (stratum corneum) is extremely thin or completely absent in most people. Lips also have almost no melanin, the natural pigment in skin that helps screen out the sun's harmful rays.

As a result of the properties of lip skin, moisture rapidly evaporates from the lips, causing them to dry out very easily. This dryness frequently results in chapping and cracking, and increases the risk of inflammation, infection and burning.

Your lips' natural tendency toward dryness and chapping is aggravated by the fact that they are more prominent than almost any other part of your body--and most of the time they are unprotected by clothing and fully exposed to the elements. While exposure to sun, wind and cold can obviously speed the rate of moisture loss, your lips aren't even safe indoors. They can suffer from lack of moisture in centrally heated or air-conditioned rooms in which the relative humidity is low.

Environmental factors are clearly one of the most important causes of lip dryness, but they are by no means the only culprit. For instance, many people's lips can also become dry when the common winter cold or flu strikes. This lip dryness happens because of people's tendency to breathe through their mouths when they get sick, inadvertently drying out their lips. Lip irritation can even be caused by certain types of food, cosmetics and cigarette smoke.

Lip dryness is also a side effect associated with a number of medications. Many medical treatments, from prescription acne drugs to chemotherapy, can affect the body's ability to maintain its natural balance of moisture and often result in dry, cracked, painful lips.