The lips present many of the same challenges as discussed previously for the eyes. They both represent transitional skin between traditional keratinized dry skin and moist mucosal skin and they both are portals of entry for foreign invaders, such as bacteria and
viruses, and other substances entering the body, such as medications. However, the lips are much more complex in terms of the substances they contact, since the lips are instrumental in eating. They contact many different foods, chemicals, and cosmetics. They are also in constant motion, much more so than any other part of the body, due to their participation in the phonation associated with speech. Yet, their cosmetic value cannot be minimized. They are an instrument of affection as delivered by a kiss and the focal point of the face. Much poetry has been written about beautiful ruby red lips through the ages.
Anatomy and Physiology
The lips must sustain pulling, twisting, and contracting forces in many different directions in order to eat and speak. To accomplish this engineering feat, they contain a transitional skin surface, known as the vermillion, overlying a complex array of muscles with supporting fat. The vermillion is the portion of the lip that is visible and adorned by lip cosmetics. It has a rich vascular supply that is visible through the thin overlying skin. The lip skin is unique in that it does not have a well-developed stratum corneum making it different than the rest of opaque facial skin. Damage to the lip tissue, from sun or cigarette heat, results in formation of a dysfunctional stratum corneum that causes the lips to lose their characteristic red color. This causes a whitening of the lips, medically known as leukoplakia, literally translated as white plaque.
As the lips age, they begin to thin and lose their characteristic shape. This is due to loss of the fat that gives the lip substance. A profile view of a child will reveal lips that protrude from the face, while the profile of a 70-year-old woman will reveal lips that are flat and even depressed from the facial surface. Many of the new cosmetic fillers, such as hyaluronic acid, are designed to replace this lost fat. The loss of lip shape is also accentuated by loss of teeth and bony gum structures that give the lips their characteristic Cupid’s bow shape. The lip muscles remain intact throughout life, but cannot make up for the loss of the underlying fat suspended over a bony frame.
Common Dermatologic Disease Conditions
The lips not only are subject to the effects of aging, but also to the insults of dermatologic disease. Infection is probably the most common serious lip problem. This is typically due to the herpes simplex type 1 virus that is responsible for fever blisters. This infection is seen as a group of clustered tiny blisters, known as vesicles, at the margin of the red vermillion. The herpes simplex virus is usually contracted during youth and remains dormant under the watchful eye of the immune system until reactivated and allowed to migrate from the nerve root to the skin surface. The virus reactivates when the immune system is overburdened. This most commonly occurs when the body is sick with another infection, hence the name “fever blister” for the herpes infection. When the body is busy fighting an infection war at another location, the herpes virus takes the opportunity to reproduce and migrate to the lip causing further pain and misery. The fever blister is contagious during the time when the blisters are filled with liquid. Once a scab has formed over the blister, the infection is no longer transmissible. This is important to the cosmetic industry, since shared lip balms and lipsticks can transmit the virus as long as the blister fluid remains moist. Herpes simplex infections are usually treated with antiviral drugs, such as acyclovir, that stop the virus from reproducing, but unfortunately cannot eradicate the virus from the body. For this reason, fever blisters are recurrent.
The lip is also the site of other infections, such as those caused by yeast. Yeast organisms may be present in the mouth and can migrate to the lips under certain
conditions. Yeast most commonly infects the corners of the mouth, a condition known as perleche. The corners of the mouth are a frequent site of saliva collection, especially in children who drool, adolescents with braces, and the elderly with poor dentition. The moisture remains in the mouth corners overnight, creating a condition known as maceration, and provides a perfect environment for the growth of yeast. Yeast typically is not transferred person to person like the herpes virus previously discussed, but can be a source of pain when cosmetics are applied or a complication of chapped-appearing lips. Perleche is usually treated with a combination of topical low potency corticosteroids and topical antifungal/antiyeast creams.
The last common lip disease to be discussed is chelitis, which simply means inflammation of the lips. Chelitis can be due to chapped lips, a condition akin to dry skin. This can result from insufficient oil being produced by the tiny yellow oil glands lining the edge of the vermillion border, as seen in elderly individuals, or due to chronic wetting and drying of the lips from lip licking, as seen in children. Both of these conditions can be remedied by the use of lip balms, lip moisturizers, or lip sticks. Good occlusion is typically required to allow these conditions to resolve, achieved through the use of oily substances, such as petrolatum, waxes, and silicones. Some elderly individuals may appear to have chronic chelitis or chapped lips due to the continual presence of peeling skin over the lips. This may be due to dryness, but may also be due to insufficient exfoliation of the lip surface or another condition known as actinic chelitis.
Actinic chelitis presents as whitish lips with unrelenting skin scale. The word “actinic” means sun. The dry skin can be removed, but is quickly replaced by the lip renewal process that is unable to make quality smooth skin. Instead, the lip is replaced every two weeks by skin made by cells containing sun damaged DNA. Actinic chelitis is a precancerous condition that can possibly culminate in skin cancer after years of neglect. Actinic chelitis is cosmetically unattractive, since the lips lose their distinct outline and red color, and is best prevented through the use of sunscreen-containing lip balms and opaque lipsticks.
Hygiene Needs
From the preceding discussion, it is apparent that the lips have some unique hygiene needs, because they are the gatekeeper of everything that is consumed orally. Typically, the lips are washed with the face, but they are regularly cleansed with saliva. They are most frequently infected by direct contact with other infected individuals through kissing. Infection that enters the body through the mouth via hand/oral transmission is far more common than infection of the lips themselves.
Skin Care Needs
The best method for keeping the lips infection free is to maintain the vermillion intact, free of fissures or openings. This requires the use of waxy, thick moisturizers designed to stay on the lips through saliva and food contact. The tiny yellow sebaceous glands that can be seen along the edge of the lips in elderly individuals do not function as abundantly with advancing age. Dry lips are also more common in the elderly due to nasal obstruction promoting mouth breathing and dentures that may not fit properly. Dry lips may also be seen at the other end of the spectrum in children who are endentulous or thumb suckers. Occlusive lip balms that prevent saliva from repeatedly wetting the skin surface are the most successful at alleviating the dry skin.
Lip balms can be further adapted to provide both lip moisturization and sun protection. A quality lip balm used on a daily basis with an SPF of at least 15 can prevent
actinic chelitis, a medically and cosmetically significant condition. A sunscreen – containing lip balm is also the best way to prevent the recurrence of a herpes simplex fever blister, since the virus is photo-reactivated. Lastly, sunscreen-containing lip balms can prevent skin cancer of the lip, a serious medical condition.