What is the function of normal skin?
The skin is one of the largest organs of the body — in an adult it is almost 2 m² and weighs about 7 kilos. It protects the body against many harmful external influences, acting as a kind of shield against sunlight, harmful substances, bacteria and fungi; this is called the barrier function. The skin also has an important role in regulating body temperature and can register and pass on signals such as pain, warmth and cold to the central nervous system.
How does the barrier function work?
The most important part for the barrier function is the horny layer (stratum corneum), which is continually renewed and repaired from the epidermis. Skin cells produced at the base of the epidermis gradually move to the surface, becoming horny cells as they go. These horny cells are surrounded by an envelope of skin fats — fatty acids, cholesterol and ceramides — which act as the “cement” between the cells.
When is the skin too dry?
Normally the evaporation of moisture through the skin is precisely regulated. When the amount of skin fats is reduced, the skin becomes more permeable to water, the balance of the skin’s moisture is lost, and the skin dries out — becoming red and scaly, and small cracks can form.
How does dry skin develop?
When the skin is regularly washed with soap it becomes clean but also literally “degreased”: the skin fats are washed away, so moisture evaporates more easily. Frequent washing with water and soap therefore causes dry skin. People who work a lot with water, soap and cleaning agents have an increased risk, especially on the hands, and some occupations carry a considerable risk (nurses, doctors, cleaners, cooks, mechanics). There is also an increased chance in winter, with central heating creating a dry atmosphere indoors and dry, cold, biting wind outside.
The main causes of drying out are degreasers (soap, other cleaning agents, chemicals) and physical factors (wind, cold, dry air).
How is dry skin treated?
When dried out, the skin itself produces extra skin fats to replace those washed away and repair the barrier. This repair takes about a week, provided the skin is left alone and given time. Rubbing a protective greasy cream into the surface gives the skin the chance to recover fully. A petroleum-jelly-containing cream generally works very well. A drawback is that such products often absorb slowly and keep the hands “greasy” for a long time, so they are especially practical to use in the evening before sleep. Some creams designed for dry skin contain extra barrier lipids such as free fatty acids, cholesterol and ceramide, which can further help repair very damaged skin.
How do I prevent dry skin?
- Avoid direct contact as much as possible with substances that damage the skin, such as solvents and soaps (including ordinary soap and shampoo) that degrease it — especially harmful combined with warm water.
- Wear gloves when possible; under rubber or PVC gloves, preferably wear cotton gloves.
- Do not heat the house too much, so the air does not become too dry; use humidifiers on the radiators to keep the humidity up.
- In cold weather, protect the skin with good clothing and gloves.
- Always use a good protective cream.
When to see a doctor
See a doctor if dry skin is very itchy, cracked, red or inflamed, or does not improve with regular moisturising, so eczema or another cause can be considered.