Dry Skin and the Skin Barrier: How to Support Your Skin

What is dry skin?

The skin is composed of several essential layers that work together to protect the body and retain moisture. Dry skin (xerosis cutis) is a skin type where the outermost protective layer, the stratum corneum, lacks sufficient lipids to retain moisture effectively. As a result, the skin loses water more rapidly and its natural defenses are compromised. This can manifest as a tight, rough, or flaky skin-feel. The skin may even become increasingly sensitive to external elements like cold, heat, or sun.

In dermatological literature, dry skin is characterized by a combination of the following factors:

• Increased transepidermal water loss (TEWL), reducing the skin's moisture retention
• A lower concentration of ceramides, fatty acids, and cholesterol, which are essential for a healthy skin barrier
• Abnormal desquamation (shedding of skin cells), leading to a rough, flaky texture
• A less efficient skin barrier, reducing protection against external stressors

The causes of dry skin can be cosmetic, such as using harsh cleansing products or aggressive skincare that strips away natural lipids. Additionally, environmental factors, genetics, and underlying skin conditions can contribute to or worsen dryness. To effectively support your skin barrier and its natural defense mechanisms, it is essential to understand the biological processes behind dry skin. This insight forms the foundation of a gentle routine tailored to the needs of dry skin.

The skin barrier: structure and function

The skin barrier plays a central role in protecting the skin and retaining vital moisture. This protective shield resides in the outermost layer of the skin, the stratum corneum. The skin barrier is frequently compared to a brick-and-mortar structure, where:

• The cells (corneocytes) act as bricks, forming the physical basis of skin protection
• The lipid matrix (ceramides, cholesterol, and fatty acids) acts as mortar, holding the cells together and locking moisture into the skin

This harmonious blend of cells and lipids ensures that the skin retains moisture and remains shielded from external elements like wind, temperature fluctuations, and microorganisms. In dry skin, this structure is less stable, reducing its protective function and leaving the skin more vulnerable to external stressors. Because the lipid matrix contains fewer essential fats, moisture evaporates from the skin more rapidly.

Dermatological literature views a compromised skin barrier as the primary factor in almost all forms of skin dryness, ranging from mild dehydration to extensive flaking.

TEWL: why skin loses moisture

In dry skin, the cells and lipid matrix within the skin barrier no longer function optimally. Consequently, the skin loses more water and its TEWL is elevated. TEWL stands for transepidermal water loss, which refers to the amount of water that evaporates from the skin's surface.

TEWL can be elevated by external, cosmetic, or biological factors:

• Cold air and low humidity
• UV radiation
• Over-washing or showering, which can deplete the skin barrier
• Harsh or overly aggressive cleansers that strip the lipid layer
  
• Reduced lipid production driven by genetics, age, or hormones

A higher TEWL means that even if you apply hydrating products, the skin cannot retain this moisture efficiently without a properly functioning barrier.

The role of lipids and fatty acids

Maintaining healthy skin is closely linked to the function of lipids and fatty acids. Lipids in the skin consist primarily of ceramides, cholesterol, and fatty acids. These compounds play a vital role in:

• Retaining moisture (minimizing TEWL)
• Defending against irritants and other external factors
• Stabilizing the skin's structure

In dry skin, studies have shown that:

• The concentration of ceramides is significantly lower
• The ratio and interaction of fatty acids are altered
• The lipid barrier functions less effectively to retain moisture

When the lipid barrier is disrupted, the skin loses moisture more quickly and becomes increasingly sensitive to external elements. Essential fatty acids, such as linoleic acid (omega-6), are critical for maintaining a healthy, resilient skin barrier. A deficiency in these fatty acids can lead to dryness and abnormal shedding of skin cells.

The skin microbiome and dryness

The skin microbiome consists of bacteria, yeasts, and other microorganisms that work together to form a protective layer on the skin. In dry skin, the diversity of this microbiome is often reduced. With fewer microbial species present, the skin becomes more susceptible to irritation from external factors like cold, heat, or UV radiation.

Studies suggest that:

• A lack of microbiome diversity weakens overall barrier function
• Dryness pushes the microbiome out of balance
• A disrupted microbiome further degrades the skin barrier

Supporting barrier repair often indirectly helps balance the microbiome, and vice versa. This explains why dry skin is prone to rapid moisture loss and increased irritation.

Environmental factors that worsen dryness

Skin dryness is heavily influenced by external conditions. The most common factors include:

• Cold, dry air
  Outdoor humidity drops, causing TEWL to rise.
• Air conditioning and heating
  These dry out indoor air, placing additional stress on the skin barrier.
• Frequent hot showers
  Hot water and standard soaps strip away natural protective lipids, hindering moisture retention.
• Sun exposure
  UV radiation damages essential lipids and accelerates moisture loss.
• Harsh cleansers or exfoliants
  These can compromise the barrier and disrupt the microbiome, leaving the skin highly vulnerable.
  
  

Genetic and hormonal factors

Dryness also stems from internal, biological causes. Dermatological literature indicates that:

• The skin naturally produces fewer lipids as we age
• Hormonal fluctuations (such as during menopause) affect barrier function
• Genetic factors heavily influence the natural production of ceramides

As a result, dry skin is driven by both genetic and hormonal factors. This explains why some individuals maintain a dry skin type long-term, even with a solid skincare routine.

Difference between dry and dehydrated skin

Skin can be both dry and dehydrated. Although these two terms are often used interchangeably, they refer to different skin needs and distinct underlying causes:

Dry skin

• Deficient in lipids (oils)
• Compromised skin barrier
• Skin feels rough, flaky, or tight all over

Dehydrated skin

• Deficient in water (hydration)
• Can occur in any skin type, including oily skin
• Typically temporary and driven by environmental factors

A complexion can be dry and dehydrated at the same time, making its care slightly more complex and highlighting the importance of a balanced, gentle routine.

Skincare for dry skin

The primary goal of skincare for dry skin is to replenish the lipid barrier, minimize water loss, and improve skin resilience by supporting its natural repair processes.

1. Gentle cleansing

Use cleansers formulated without harsh sulfates or stripping ingredients to avoid removing essential surface lipids and to preserve your microbiome.

2. Lipid support

Natural plant oils rich in fatty acids support barrier repair. These oils contain a complex spectrum of nourishing fatty acids. Essential fatty acids, such as linoleic acid, play an important role in reinforcing the skin barrier.

3. Soothing hydration

Alcohol-free hydrosols and gentle facial mists provide lightweight, instant hydration without putting stress on the skin.

4. Minimalist routines

Piling on too many products can easily overwhelm and disrupt both the skin barrier and the microbiome.

5. Protection from the elements

Wind, cold temperatures, and sun exposure accelerate moisture loss. Proper daily protection reduces unnecessary stress on the barrier.

Common misconceptions

• Dry skin is solely caused by not drinking enough water
  While internal hydration is important, your skin barrier ultimately dictates how much moisture your skin can retain. Minimizing TEWL is the primary key.
• Layering more skincare products will cure dryness
  Applying too many steps can overload your skin, easily disrupting the barrier and its microbiome.
• Aggressive scrubs help clear away flakes
  Vigorous physical scrubbing is far too harsh for a compromised barrier and typically worsens the underlying damage.
  
  

When to seek professional help

In certain cases, the skin barrier cannot be fully restored through gentle cleansing, basic protection, or over-the-counter care alone. You should consult a doctor or dermatologist if:

• Dryness is accompanied by pain, cracks, or bleeding
• You suspect a clinical skin condition like eczema
• The skin becomes visibly inflamed or infected
• Extreme dryness persists despite consistent, gentle skincare
  
  

Further reading: scientific sources

• PubMed dermatological research on xerosis
• European Academy of Dermatology & Venereology (EADV)
• Dermatological textbooks on skin barrier function and lipids

These resources provide deep insight into the scientific basis of skin barrier function, moisture loss, and dryness. They are not a substitute for professional medical advice.