Explanation of the causes and mechanisms of chapped and cracked skin | Rohto Pharmaceutical: Product Information Site

<Things you should know> Correct knowledge about "cracked and chapped skin" (1) Explanation of the causes and mechanisms of cracked and chapped skin

What are chapped and cracked skin?
Causes (mechanisms) of cracked and chapped skin
Factors that make cracks and chapped skin more likely (time of year, daily life)

Chapped and cracked skin is a common sight during the cold season. Many people suffer from painful cracks in the skin of their hands and feet. But why do chapped and cracked skin occur in the first place? And how do they differ from chapped hands or chilblains? We'll explain in detail, supervised by a dermatologist.

What are chapped and cracked skin?

Chapped or cracked skin on the hands and feet can cause painful cracking. Let's start by explaining the symptoms of chapped or cracked skin and how it differs from dry, chapped hands and chilblains.

Glossary

Human skin has a three-layered structure: the "epidermis," which is the outermost layer and protects the skin from external stimuli; the "dermis," which lies beneath the epidermis and maintains the skin's moisture and elasticity; and the "subcutaneous tissue," which is the innermost layer and is mainly composed of fat.
A "crack" refers to a fissure or fissure. It refers to a thin, deep, linear cut that reaches the deeper layers of the epidermis or even the dermis. On the other hand, "chapped skin" refers to a condition where a crack progresses, causing bleeding or inflammation and redness in the affected area. In other words, chapped skin can be considered an aggravated state of a crack. When skin becomes chapped, it looks painful, causes pain, and can sting when exposed to water, often interfering with daily life.

What's the difference between this and chapped hands?

Hand irritation refers to a condition where the hands become dry and itchy due to water, detergents, and various other external irritants. Inflammation that causes itching and redness may be present beneath the skin.
It usually starts with dryness, and can affect the entire hand or be localized, affecting only certain fingers. Scratching can worsen the condition and make it harder to heal. Cracks and fissures may also be present as symptoms of dry hands.

What's the difference between this and chilblains?

Chilblains are caused by poor blood circulation due to cold temperatures. They commonly occur in the extremities, such as the hands and feet, where blood flow is poor. They are especially likely to occur after getting wet and then being suddenly exposed to cold temperatures.
To prevent chilblains, it's important to protect your skin from the cold. Wear gloves, thick socks, and a hat that covers your ears to ensure proper protection. Foods that improve peripheral blood circulation and taking baths are also effective. Additionally, consuming vitamin E, which supports smooth blood flow, is recommended.

Causes (mechanisms) of cracked and chapped skin

Chapped and cracked skin is common in winter because it is affected by lower temperatures and dry air. When temperatures drop, the amount of sweat and sebum secreted decreases, making the skin more prone to dryness. On top of that, the dry air irritates the skin, further depleting its moisture.

The condition of the skin at this time can be easily imagined by comparing it to mochi (rice cake). Freshly made mochi is very soft, and even if you pull and stretch it with both hands, it won't crack. However, if you leave the mochi as it is for a long time, like a kagami mochi (decorative rice cake), the surface dries out and cracks when pulled.

The same thing happens with skin. When skin loses moisture and remains dry, it becomes more prone to cracking. When the skin is then stretched by bending and straightening the fingers, the elasticity of the skin surface cannot withstand the force, and cracks form. This is why cracks and chapping are more likely to occur on the extensor side of the finger joints (the side opposite to the bending side of the joint, the outer side).

These cracks can occur not only on the hands but also on the feet. They are commonly seen on the heels. Cracks can also form when the skin on the heels hardens like a callus.

In the case of heels, not only is the skin prone to dryness, but the skin also hardens as a defense mechanism to support the body's weight, making it more susceptible to cracking. For example, it's the same principle as calluses that form on the hands of craftsmen; areas constantly exposed to external stimuli thicken the skin to protect the inside. People who are overweight, those who put weight on their heels when walking, and those who walk barefoot on hard floors are especially prone to heel cracks.

The lips are also one of the areas prone to cracking. Because the skin is thin and has difficulty retaining moisture, it is important to prevent dryness with regular care.

Factors that make cracks and chapped skin more likely (time of year, daily life)

Finally, we will discuss seasons, habits, and occupations that are prone to causing chapped and cracked skin. It's important to understand the factors that contribute to chapped and cracked skin beforehand.

What season is most prone to chapped and cracked skin?

Chapped and cracked skin is most common in winter because it is largely caused by low temperatures and dry air. However, it can also occur in summer if there is strong daily irritation.
For example, rashes caused by detergents or various other substances, or irritation from friction, can also occur. When factors that damage the skin are present, the skin's turnover process can be disrupted, leading to increased keratinization and a loss of elasticity, which can easily cause cracks. Not only external irritants, but also the severity of the irritation to the skin will likely influence how easily cracks and chapped skin develop.
When are cracks and chapped skin most likely to occur in daily life?

This often happens when washing dishes or doing other water-related chores. After using water, immediately dry your hands. If you leave them wet, the water can evaporate, potentially taking moisture from your skin with it, making you more prone to cracks and chapping. Use hand cream or other moisturizing products frequently.
In addition, those who frequently handle cardboard or paper should be careful, as the paper can strip moisture and oil from their hands, worsening dryness. Skin damage from external stimuli can also be a cause, making it more likely to occur in people whose jobs involve heavy use of their hands.
What occupations are said to be prone to cracked or chapped skin?

This condition is commonly seen in people who frequently use detergents or wash their hands, such as housewives, cooks, barbers, beauticians, medical professionals, nail technicians, and flower coordinators. Mothers raising babies are also more likely to experience it.

Supervised by: Dr. Yuki Horiuchi, Director of Akihabara Skin Clinic
After graduating from the Faculty of Medicine at Tokyo Women's Medical University, she worked at dermatology and cosmetic clinics in Tokyo before opening Akihabara Skin Clinic in 2007. She is a certified specialist of the Japanese Dermatological Association and is also a member of the Japanese Dermatological Association, the Japanese Society for Aesthetic Dermatology, and the Japanese Society for Laser Medicine.

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