The Yomiuri ShimbunMany people suffer from itchy skin in winter, when skin tends to become dry. Why does the itching occur, and are there any means to prevent it?
There are barriers on the surface of our skin that prevent irritations and block the intrusion of foreign substances. These are the horny layer and moisture barriers.
In the horny layer, cells called corneocytes are lined up evenly like a brick wall. Corneocytes are dead cells, which are seen in flaky skin. The moisture barriers comprise sebum and sweat, and cover the horny layer.
“The horny layer holds water inside it like a sponge. The moisture barriers are like natural hydrating creams, and prevent the water from drying up,” said Prof. Yasushi Suga, a researcher of dermatology at Juntendo University Urayasu Hospital.
Healthy skin is soft and moisturized. But in winter, the amount of sweat and sebum decreases. As cold weather restricts the circulation of blood, secretions that work to keep water inside the horny layer also decrease.
If this happens, skin becomes dry and hard. The surface of such damaged skin forms cracks or rubs off. As a result, gaps form between skin cells and it becomes easier for moisture to evaporate through these gaps. If the skin’s surface becomes flaky, the condition is called dry skin.
Dry skin makes it easier for dust and other foreign substances to enter the body from the outside. Also, dry skin tends to easily feel irritated by, for example, friction from clothing.
The sensory nerves that feel itching are usually located deep under the skin’s surface. But if the skin becomes dry, the nerve cells grow longer to be closer to the surface, so as to be on alert against foreign substances and irritations.
When foreign substances or irritations touch the nerves, there is an itching sensation. Suga said, “Feeling itchy is primarily a rational mechanism to prompt scratching, to clean off things like foreign substances.”
However, in modern lifestyles in which people wash their bodies with soap and shampoo and air conditioners are widely used, skin easily becomes dry and tends to react even to slight stimuli.
If a person scratches their skin, it becomes hypersensitive and the itching becomes stronger.
If the skin is scratched too much, eczema can appear or the skin can suppurate due to an infection.
Takafumi Eto, chief of the Dermatology Department at Tokyo Teishin Hospital, said, “It’s important for people whose skin tends to be dry to keep it moisturized to prevent the condition from worsening and to keep it in good condition.”
If the itchy feeling continues or the itching spreads even after moisturizing, you should go to a dermatology clinic.
As we age, secretions of sebum and other substances decrease, and the skin’s surface becomes dry more easily. Dry skin becomes noticeable in our 40s and 50s.
Excessive washing no good
To prevent dry skin, a lifestyle review is important.
Nobuko Yoshiki, head of Yoshiki Hifuka Clinic Ginza, a dermatology clinic in Tokyo, said, “It’s not necessary to wash the whole of your body every day using soap.”
This is because excessively washing the body removes substances that keep sebum and water in the skin.
On body parts that more easily become dry, such as the back, around the waist and below the knees, there is less sebum.
Yoshiki recommends washing these areas with soap once or twice a week and only with hot water on the other days.
Moisturizing your skin after washing is also important. It is recommended to thoroughly coat dry areas with a commercially available moisturizing cream until it is absorbed.
The following morning, the skin that was covered with the cream should be checked. If it has become dry again, more cream should be applied. This should be done once or twice a day.
With dry skin, irritation from friction or tight clothing increases the itchy feeling. Thus it is better to avoid wearing clothes with hard seams and fuzzy materials. Socks and underwear should not fit too tightly, and it is better to choose stretchy clothes.