What is dry skin?
Dry skin, also called xerosis, is a very common skin condition that occurs at all ages. Usually, it doesn't represent a serious problem but sometimes it can be difficult to treat. Moreover, it might be correlated to other skin diseases or associated to pathological conditions such as diabetes, hypothyroidism and hyperthyroidism, Sjögren syndrome, malnutrition.
What does it look like?
Involved skin appears dehydrated, peeled, irritated and inflamed. It feels rough, scaly, sometimes painful, and itchy. Severe conditions may be characterized by intense redness and itchiness; skin shows the tendency to crack, causing deep fissures that may bleed and they are signs of extremely dry skin.
Dry skin at the microscope:
Skin represents our barrier against the environment and it consists in three layers: hypodermis, the deepest layer, constituted mainly by adipose tissue, with vessels, nerves; dermis, constituted by connective tissue, with collagen and elastin fibers, blood vessels, oil glands, hair follicles, sweat glands; epidermis, the outer layer, constituted by keratinocytes which divide and mature moving from the basal layer to the stratum corneum (the outermost compartment of the epidermis). Keratinocytes, localized in the stratum corneum, feature an insoluble structure composed of several proteins called cornified envelope, cytoplasm filled by keratin filaments and nuclear dissolution. These cells are embedded into lipid layers constituted by cholesterol, fatty acids and ceramides. Stratum corneum provides skin hydration1 and, in particular, lipids play a significant role against evaporation holding water. Sweat and oil glands products, skin natural moisturizing factors (consisting of a mixture of highly hygroscopic molecules as amino acids, sugars, lactic acid, urea) partecipate to moisture content maintenance, acting as endogenous humectants.
Skin owes its soft, pliable texture to its water content. Dry air (low humidity), probably the most common cause of dry skin, causes an evident reduction of water content. Furthermore, dry skin results when lipids are depleted and there is not enough water in the stratum corneum for it to function properly. Atopic dermatitis, a common dry skin condition in childhood, shows reduced lipids levels in the stratum corneum and, consequently, an important loss of water.2
Severe dry skin is a feature of the inherited group of disorders called ichthyosis: the most common form of ichthyosis is defined ichthyosis vulgaris, characterized by fine scaling that is most prominent over the legs and usually presents within the first few months of life.3
Furthermore, xerosis may represent a symptom in other skin diseases such as asteatotic eczema, lichen and psoriasis.
What causes dry skin?
Simple causes of lipids depletion include harsh soap, itchy clothing, long and hot showers or baths. An important environmental factor is represented by the exposure to hot or cold weather with low humidity levels. Xerosis often worsens in the winter, when several factors contribute to skin dryness: low temperature and low humidity associated to very hot and drying heating, cause a decreased amounts of water in the stratum corneum. During summer, constant exposure to air conditioning may produce similar effects.
Several drugs, as diuretics or topical and systemic retinoids, may temporary cause dry skin and, generally, it resolves interrupting the treatment.
In elderly, metabolic changes, tendency to reduce liquid intake, associated to the physiological skin aging process (keratinocytes move slowly from the basal layer of the epidermis to the stratum corneum and oil glands are less active), determine xerosis, thinning, and lost of elasticity. Hormone imbalances that occur in menopause, hypothyroidism, and hyperthyroidism can also experience severe skin dryness.
Why Do I need to contact a dermatologist?
Chronic or severe dry skin problems require a dermatologist's advice. It's important have a diagnosis to exclude concomitant skin diseases as mentioned above. Dermatologist may evaluate and identify causes and get the necessary treatment: commonly, for people with dry skin, the best treatment is a moisturized cream or emollients, but if necessary, he may prescribe a steroid cream or ointment in association. For clinical picture characterized by intense itchy, which interferes with daily activities and sleep, antihistamine pills may be prescribed.
Treatment and prevention
These are easy suggestions that are important to keep in mind:
- Choose short showers over baths. Long baths or showers, especially in hot water, increase the loss of natural oils from the skin and worsen skin dryness. The shower should be in warm rather than hot water. Apply a moisturizer after shower or hands washing.
- Apply moisturizing creams, emollients or ointments moisturizers several times a day: they are fundamental in dry skin treatment because they reconstitute cutaneous hydro-lipidic film holding water in the skin. Cream moisturizers, when applied they disappear when rubbed into the skin because of they are more popular than other treatments. They protect damaged and sensitive skin and make skin softer and smoother. They preserve natural skin lipids and limit dehydration trapping and sealing water in the stratum corneum.
- Choose a non-alcohol-based moisturizer.
- Use a mild non-soap skin cleanser. Harsh soaps remove the oils from the surface of the skin and dry it out.
- Avoid antibacterial soaps.
- Place a humidifier in your home or add it to the central heating system to maintain the air moisturized during the winter and in dry weather.
- Avoid rubbing or scratching the skin.
- Wear gloves, hats, and scarves in the winter.
- Avoid dehydration caused by drinking alcohol and by neglecting to replace fluids lost through sweating.
- Avoid itchy clothing because it might get more itchy. Dry skin is especially sensitive to contact irritants and it may worsen itching and redness.
For more information about dry skin condition contact:
1 Madison KC. Barrier Function of the skin: "La Raison d' Être" of the epidermis. J Invest Dermatology 2003; 121 (2): 231-241
2 Imokawa G, Abe A, Jin K, et al. Decreased level of ceramides in stratum corneum of atopic dermatitis: an etiologic factor in atopic dry skin?. J Invest Dermatology 1991 Apr; 96: 523-526.
3 Hoffjan S, Steimmler S. On the role of the epidermal differentiation complex in ichthyosis vulgaris, atopic dermatitis and psoriasis. British Journal of Dermatology 2007; 157: 441-449.