Causes of Sensitive Skin and Proper Care - Why Your Skin Stings and Turns Red

What Is Sensitive Skin?

Sensitive skin is not a medical diagnosis but a general term describing a condition where the skin overreacts to external factors that normally wouldn't cause irritation. Specific symptoms include stinging when applying cosmetics, redness from temperature changes, itching from clothing friction, and tightness after washing the face.

Surveys show that approximately 60-70% of Japanese women identify themselves as having "sensitive skin," but most cases involve temporary barrier function decline that can be improved with proper care. True sensitive skin (congenitally thin stratum corneum, high nerve fiber density, etc.) is estimated at only 10-20% of the population.

The essence of sensitive skin is "compromised barrier function." When healthy skin barrier functions normally, external irritants are blocked at the stratum corneum and cannot reach the skin's interior. When the barrier breaks down, irritants reach the nerve endings in the epidermis, causing stinging and burning sensations.

How Barrier Function Breaks Down

The skin's barrier function consists of corneocytes and the intercellular lipids (ceramides, cholesterol, fatty acids) that fill the spaces between them. This structure is often compared to "bricks and mortar" - corneocytes are the bricks and intercellular lipids are the mortar. When the mortar (intercellular lipids) is insufficient, moisture evaporates through gaps between the bricks and external irritants can penetrate.

As explained in detail in dry skin barrier repair, barrier function decline creates a vicious cycle of dryness and inflammation: ceramide reduction → increased moisture evaporation → stratum corneum dryness → micro-crack formation → irritant penetration → inflammation → further barrier destruction.

External factors that compromise barrier function include excessive cleansing (harsh surfactants), over-exfoliation, alcohol-containing cosmetics, UV radiation, dry environments (air conditioning, low winter humidity), and friction (rubbing with towels).

Factors That Worsen Sensitive Skin

Beyond external factors, internal factors also aggravate sensitive skin. Stress increases cortisol secretion, and cortisol suppresses ceramide synthesis, reducing barrier function. Sleep deprivation robs the skin of repair time and disrupts turnover cycles.

Hormonal fluctuations also play a role. During the progesterone-dominant phase before menstruation, skin becomes more sensitive, and products that normally cause no issues may feel irritating. Estrogen decline during menopause leads to skin thinning and reduced barrier function.

Regarding diet, alcohol, caffeine, and spicy foods can dilate blood vessels and worsen redness and flushing. Food allergies or intolerances may manifest as skin inflammation. If you notice your skin worsening after consuming specific foods, keeping a food diary to identify triggers can be effective.

Choosing Skincare for Sensitive Skin

The fundamental principle of sensitive skincare is "subtraction." The more products you layer, the higher the risk of irritation, so the goal is maximum barrier repair with minimal steps. (Books on sensitive skincare can guide your product selection.) The basic routine is cleansing → moisturizing → sunscreen, with additional items introduced gradually once the skin stabilizes.

Ingredients to avoid include alcohol (ethanol), fragrance, colorants, essential oils (especially citrus), menthol, and witch hazel. While these may be fine for healthy skin, they can irritate skin with compromised barrier function.

Recommended ingredients include ceramides (the key to barrier repair), niacinamide (promotes ceramide synthesis, anti-inflammatory), panthenol (anti-inflammatory, moisturizing), allantoin (soothing), and madecassoside/centella asiatica extract (anti-inflammatory, promotes collagen synthesis). These are well-tolerated by sensitive skin and promote barrier recovery.

Specific Methods for Cleansing and Moisturizing

For sensitive skin cleansing, minimizing burden on the skin is the top priority. Choose cleansers with amino acid-based surfactants (sodium cocoyl glutamate, sodium lauroyl methyl alaninate, etc.) as the main ingredient. Use a foaming net to create rich lather and wash so that your hands don't directly touch the skin through the cushion of foam.

Keep cleansing time within 30-60 seconds and rinse gently with lukewarm water around 32°C. Pat dry with a towel rather than rubbing - this is an absolute rule. In the morning, washing with lukewarm water alone without cleanser is often sufficient.

Apply moisturizer within 1 minute of cleansing. Applying while the stratum corneum still contains moisture efficiently prevents evaporation. Use a ceramide-based moisturizer as your foundation, and layer a thin coat of petroleum jelly over particularly dry areas for an occlusive (sealing) effect. (Ceramide moisturizers are essential for barrier repair.)

How to Test New Products

Patch testing is essential when people with sensitive skin try new skincare products. Apply a small amount behind the ear or on the inner arm, and confirm there is no redness, itching, or stinging after 24-48 hours before using on the face.

When starting to use on the face, apply to a small area first (such as part of the cheek), and gradually expand the area if there are no problems. Introduce new products one at a time with at least 2 weeks between each. Changing multiple products simultaneously makes it impossible to identify the cause if problems occur.

Even products labeled "for sensitive skin" or "low irritation" may not suit all sensitive skin types. Develop the habit of checking ingredient lists to verify they don't contain ingredients your skin tends to react to.

When to See a Dermatologist

If self-care doesn't improve your condition or symptoms worsen, consider visiting a dermatologist. Particularly if redness persists, eczema or rashes recur, itching is severe, or skin is peeling, conditions like adult atopic dermatitis, contact dermatitis, or rosacea may be underlying causes.

Dermatologists can identify causes through patch testing (identifying contact allergies), skin biopsy (histological examination), and blood tests (allergy testing), then provide appropriate treatment. Short-term topical corticosteroids are used for mild inflammation, while heparinoid substances and ceramide-containing medications are prescribed for barrier repair.

Sensitive skin is less about "curing" and more about "managing well." Understanding your skin's triggers, avoiding them while maintaining barrier function through consistent care, leads to long-term skin stability.