Preventing & Managing Dry Skin Dry skin, also called xerosis, is rough, scaly skin that is dry to touch and less elastic than normal skin. It appears most commonly on the forearms, front of the lower legs and back of the hands. Although dry skin is not a life-threatening condition, it can cause considerable discomfort and make the skin susceptible to other, more serious, consequences, such as infection. It is estimated that up to 85% of the elderly population experience dry skin on an on-going basis. Dry skin also affects younger people, but less frequently and to a less severe level. This article describes the pathophysiology of dry skin. It also reviews the factors that contribute to the development of dry skin and strategies that can be used to prevent and manage dry skin. The Skin The skin is the largest organ in the body. It performs many critical functions, which include: • acting as a protective barrier between the body and the environment; • controlling the movement of moisture into and out of the body; • producing about one-third of the body's excretions in the form of swear, sebum (an oily substance secreted by the sebaceous glands), etc; • facilitating the absorption and excretion of some medications and toxins; • mediating sensory experiences; • assisting in temperature control (Refer to the PHARMAwise edition on Managing Fever); • providing protection from ultraviolet radiation (Refer to the PHARMAwise edition on Sun Protection: A Wise Choice); and • synthesizing vitamin D As illustrated in Figure 1, the skin is composed of two layers: an outer epidermis and an inner dermis anchored by subcutaneous tissue to underlying muscle and bone. The cells at the base of the epidermis (basal cells) continuously form new cells that contain an durable protein called keratin. These keratin- containing cells slowly move to the skin surface where they are eventually shed and replaced by more cells arriving from the base of the epidermis. During transit to the surface, the cells die, thicken and flatten. The surface of the skin, or stratum corneum, is therefore composed of flat, keratin containing, dead cells called squamous cells. Keratin absorbs many times its weight in water. The water retained by the keratin in the squamous cells is largely responsible for giving the stratum corneum its flexibility. Spaces between the squamous cells contain a mixture of water-soluble substances known collectively as natural moisturizing factor. Natural moisturizing factor also plays a role in holding water in the stratum corneum. Sebum, which forms a protective, oily layer over the skin surface, plays an important role in limiting the evaporation of water from the stratum corneum. Causes & Consequences of Dry Skin At one time it was assumed that dry skin resulted from inadequate production of sebum or the removal of sebum from the skin surface through chaffing, excessive washing, etc. Consequently, dry skin was managed by rubbing oils and greasy products into the skin. Today, we know that while a lack of natural oils contributes to the drying of the skin surface, the main problem with dry skin is a lack of water within the stratum corneum. The optimal water content of the stratum corneum is somewhere between 10% and 20% by weight. When the moisture content of the skin drops below 10%, it begins to feel "dry" and its elasticity, barrier and absorptive characteristics deteriorate. Symptoms of dry skin include flaking, chapping and a feeling of roughness over the skin surface. The dry areas are generally itchy, but scratching simply aggravates and increases the moisture loss from the skin. If the moisture content of the skin is very low, the skin cracks and becomes red and inflamed, making it more susceptible to infection from microorganisms in the environment. Factors Contributing to Dry Skin A list of factors that contribute to dry skin is provided in Table 1 Changes in the skin that accompany aging account for the increased incidence of dry skin among elderly people. As individuals age, the rate of epidermal cell turnover decreases. This causes the epidermis to thin and the dermis to shrink. The junction between the dermis and epidermis flattens and the fat in the subcutaneous tissue decreases. The keratin in aging skin has a tendency to adhere, reducing its ability to hold water and making the skin less flexible. There is an age-related loss of blood vessels in the dermis, which means the skin receives less water from the body's circulation. The hormonal changes accompanying aging result in a reduction in sebum output. Because androgenous hormones control sebum production, dry skin is more common in women than in men. This difference is even more pronounced as women and men age. Water in the skin constantly evaporates into the air. When the humidity in the air is more than 30%, the water that evaporates is replaced by water delivered to the skin from the blood vessels. With a lower humidity, however, the evaporation of water from the skin increases and replacement mechanisms cannot keep up. Dry skin results. Air conditioning during the summer and heating systems during the winter are common causes of low humidity. Other factors that increase the loss of moisture from the skin are exposure to high winds and excessive sun exposure. Anything that causes physical damage to the stratum corneum (burns, abrasions, etc.) disrupts the skin's normal moisture retention mechanisms. Certain activities remove the natural oils from the surface of the skin, thereby compromising the skin's ability to retain moisture. These include excessive use of soaps and disinfectants; repeated exposure to solvents; excessive bathing (more than once per day); and bathing with very hot water. Dry skin often accompanies other skin disorders, such as atopic dermatitis, as well as conditions such as hypothyroidism, diabetes, dehydration, malnutrition, malignancies, hepatic or renal diseases, psychoneurosis and conditions associated with excessive sweating. Other factors thought to contribute to dry skin are smoking and stress. Table 1: Factors that Contribute to Dry Skin • advanced age • gender • low humidity • high winds • excessive sun exposure • damage to the stratum corneum • excessive use of soaps and detergents • excessive bathing • bathing with very hot water • skin disorders & systemic conditions • smoking • stress Preventing Dry Skin The prevention of dry skin begins with identifying the factors that might cause dry skin and then, whenever possible, eliminating these factors. For example: • Use a humidifier (freestanding or installed in the heating system) or even a pan of water on radiators if indoor humidity is low. • If possible, avoid air-conditioned environments • Keep room temperatures as low as possible during winter months. Environmental humidity is low in the winter, but it is even lower in a heated indoor environment. • Use super fatted soaps. They leave a film of oil on the skin surface, thereby supplementing the moisture-retaining properties of the skin's natural oils • Avoid using harsh soaps, detergents or solvents on the skin • Be cautious about using products containing fragrances or dyes. Fragrances or dyes may be allergenic or irritating to sensitive skin • Limit bathing to short baths or showers no more than once per day. While bathing does help to moisturize the skin, frequent or lengthy bathing can remove the skin's protective oils and over- hydrate the skin. Over-hydrated skin is more susceptible to physical damage and infections. • Bathe in water temperatures between 32° and 40.5° C. Water temperatures below this range increase the evaporation of water from the skin, and temperatures above this range remove the natural skin oils and may scald the skin. • After bathing, pat the skin dry. do not rub the skin since the rubbing action can remove the oils on the skin. While the skin is still moist, apply a moisturizer to seal the skin and minimize evaporation of the newly added moisture • Avoid wearing wool or rough clothing against the skin. These textures can irritate the skin and remove its natural oils. • Drink at least 6 to 8 glasses of water each day. The body must ingest enough water to continually replace the water that evaporates from the skin. • Be vigilant about wearing a suitable sunscreen. • Quit smoking. Managing Dry Skin Once the skin is dry, treatment involves eliminating causative factors, replacing the water deficit in the skin, minimizing the loss of water from the skin, and treating bothersome symptoms. Replacing the water deficit in the skin: Replacing the water deficit in the skin can only be achieved by adding water to the stratum corneum. This is most effectively accomplished through bathing (short baths or showers no more than once per day, using water temperatures between 32° and 40.5° C) or through application of wet compresses (5mL of bath oil in 125mL of warm water). Moisturizers and skin oils do not hydrate the skin. Their primary benefit is in slowing the evaporation of water from the skin. Minimizing the loss of water from the skin: Water absorbed through bathing or use of wet compresses hydrates the skin, but the water rapidly evaporates unless steps are taken to prevent moisture loss through the skin. Moisturizers and bath oils act primarily by leaving an oily film on the skin surface through which water cannot readily escape. used as follows, moisturizers and bath oils minimize the loss of water from the skin: Apply a moisturizer to the skin after bathing ,several times during the day, and at bedtime. A non-medicated, fragrance free moisturizer should be used unless symptoms other than dryness need to be treated. Ointments have a higher content of oil than creams and are generally considered to provide greater protection from moisture loss through the skin. Ointments can, however, be greasy and are often not acceptable to the individual. Lotions tend to be more drying than creams. Gels are so drying that they are not recommended for dry skin. Add bath oils near the end of the bath. If bath oils are added at the beginning of the bath, they may prevent the water from getting adequately absorbed into the skin. When added at the end of the bath, the bath oil coats the already hydrated skin as the individual stands up in the tub. It is important to remember that bath oils make the tub surface slippery, and after using a bath oil, the skin must be patted dry to prevent the oil from being rubbed off with a towel. Treating Bothersome Symptoms: Dry skin is accompanied by many bothersome symptoms, including a rough surface texture, itchiness and redness. When an individual requires relief from these symptoms, a medicated moisturizer can be used. It is important to select a moisturizer that contains medication(s) to target the bothersome symptom(s). Keratin-softeners, such as urea and alpha-hydroxy acids (AHAs), can be used to treat rough skin. They soften the skin and improve its appearance, but do not actually increase its water content. In fact, they draw water from the skin and therefore have the potential to actually irritate. To prevent irritation, keratin softeners should only be applied to damp skin. Therapy with keratin softeners should be started with a few applications per week, building up every day as long as irritation does not occur. Adding baking soda or oatmeal to the bath can be used to relieve itchiness. Another option for managing itchy skin is adding a mixture of 500mL of cornstarch and 1 liter of water to the bath. If dry skin is very itchy, oral antihistamines can be used with caution if other medications are being taken simultaneously. Oral antihistamines are an especially good choice for treating itchiness during the night. Antihistamines and local anesthetics applied to the skin should be avoided because of their potential to sensitize the skin. Moisturizers containing hydrocortisone 0.5% can be used to relieve itchiness as well as redness. If the redness and itching do not resolve within 7 to 10 days of treatment, a physician should be consulted before its use is continued. Don't Forget Your Lips The lips are one of the areas of the body most vulnerable to dry skin. There are many reasons for this: • The skin is thinner on the lips, providing a less effective barrier. • The lips do not contain sweat glands, so they are more likely to be dry. • The lips do not contain melanin, so they are more susceptible to sunburn (Refer to the PHARMAwise edition on Sun Protection: A Wise Choice) • Saliva contains enzymes that irritate the lips The best way to prevent dry lips is to use a lip protectant during cold, windy or dry weather. People who spend time outdoors during daylight hours should wear a lip protectant containing a sunscreen with an SPF of at least 15. Dry, chapped lips are managed by wetting them (using water, but not saliva) and then applying a lip protectant. People with dry lips should be cautioned not to lick their lips. Saliva irritates the lips, making them even drier. PHARMAwise is authored and published by Dawn M. Frail, B.Sc. (Pharm), M.Sc. and made possible through the support of the Pharmacy & Apotex Continuing Education (PACE) program, the Apotex Advisory Board and your pharmacist. Reference to articles contained in this infoletter are available by contacting the Apotex Professional Affairs Department at 1-800-268-4623, extension 8456. PHARMAwise is intended to provide drug and health information to care providers. The publisher, sponsor, and distributor are not responsible for losses arising from the use of information in this publication.