Dry skin (medically known as xerosis) usually appears rough, scaly and even itchy. Xerosis can be caused by factors ranging from cold weather to frequent showering, and is also a common symptom of several chronic skin diseases. While xerosis is not a critical condition, it can cause significant discomfort, affect one’s appearance, and accelerate skin’s aging.
So what causes xerosis and how can it be managed?
What is dry skin?
In normal skin, lipids and natural moisturizing factors (NMFs) are needed to maintain barrier function and optimal skin hydration. NMFs attract water molecules while lipids controls the amount of skin that evaporates from the skin surface.
NMFs keep the skin hydrated by binding to water and holding onto it, preventing excessive water loss as the skin cells have sufficient hydration to remain turgid. An effective skin barrier keeps the skin’s water content at a healthy level of 15 to 20 per cent.
Dry or dehydrated skin has reduced NMF levels which compromises the skin’s ability to retain water. As a result, moisture is lost much faster than replenished. When the skin’s water content falls below 10 percent, visible scales form and the skin starts to have a rough dry appearance. Individuals with dry skin can also often notice cracks or experience flaking.
The precise organisation of lipids are important as it determines the amount of water that can be trapped in the skin. In healthy skin, sufficient lipids are present to keep Transepidermal Water Loss (TEWL) values low, as less water is lost to the surroundings.
What causes dry skin?
Dry skin arises largely due to abnormal epidermal differentiation.
The epidermis is produced by cells that divide and proliferate in the deeper skin layers before travelling towards the skin surface. At the surface, skin cells mature, flatten and die. These dead skin cells are sealed together with fatty lipids to form a continuous skin barrier. This process is termed epidermal differentiation.
A disruption in the skin barrier can cause epidermal differentiation to become abnormal and the skin barrier function to become damaged. This disruption can happen for a variety of reasons:
- Genetics: Dry skin is a major manifestation of several skin diseases such as atopic dermatitis (eczema) or psoriasis (itch) which has a genetic component.
- Aging: In aging skin, a marked decline in lipid and water content ultimately impairs skin barrier function. A decline in filaggrin, a protein that produces NMFs, is also observed as we age, leading to diminished NMF levels
- Low humidity: Low humidity causes less amino acids and filaggrin to be produced in the stratum corneum, as they require optimal humidity to function well. As a result, NMF levels are lower.
- For example cold dry weather often causes ‘winter itch’ where skin is rough, red and irritated. Winter xerosis is aggravated by the presence of hot, dry air from modern central heating, causing impaired desquamation and scaling. You may also experience dry skin in hot weather if most of your time is spend in air-conditioned surroundings.
- Sun exposure: Ultraviolet (UV) radiation from the sun can also affect normal epidermal proliferation by compromising the skin barrier’s function and resulting in greater water loss to the environment.
- Frequent bathing: Such habits, especially with hot water, can further irritate the skin and damage the skin barrier function. Hot water should be avoided, and a shorter bath duration is recommended.
- Other environmental factors: Chemical agents such as soaps, lotions, perfumes or detergents can also contribute to xerosis.
How to replace skin’s water content
We often see buzz about the importance of hydrating our skin, but how exactly do we ensure our skin is hydrated enough?
Currently, the best approach to treating dry skin is to restore normal abnormal epidermal differentiation by using ingredients that can easily penetrate the skin and prompt it to produce healthy levels of lipids again. Effective ingredients are lipids, humectants and antipruritic agents:
Other types of lipids that are not found naturally in our body can also be beneficial by serving as an occlusive layer, such as petrolatum. They prevent water loss to the surroundings by trapping it. A common example of petrolatum is Vaseline.
Humectants, such as glycerol, lactic acid, hyaluronic acid and urea, attract and retain water in the skin. Glycerol or urea can improve skin elasticity and barrier function, and compensate for the lower levels of NMF in dry skin. Hyaluronic acid is a humectant capable of holding up to 1000 times their own weight in water, locking in moisture for the skin.
Antipruritic agents block histamine release to interfere with the itch sensation and break the itch-scratch cycle.
An ideal ingredient should prompt the skin to restore epidermal differentiation, reduce excessive water loss and itching. Multi-CERAM Moisturizer is dermatologist-formulated to treat eczema and dry skin with pharmaceutical grade ingredients. An ultra-intensive formulation, this moisturizer relies on ceramides, plant seed oils, sodium hyaluronate and glycerin to repair the skin barrier and restore skin moisture.
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Meet with Dr. Teo Wan Lin, an accredited dermatologist at TWL Specialist Skin & Laser Centre, for a thorough consultation to determine the most suitable treatment for your skin.
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