Dry Skin (Xerosis / Asteatotic Dermatitis) | Dermatology in Hiroo & Ebisu, Tokyo | Yasashii Clinic

Medically Reviewed by: Takafumi Suzuki, MD — Primary Care in Dermatology, Internal Medicine & Allergology; Specialist in Anesthesiology

Written by: Yasumasa Ohno — Business Development & Content Manager, Yasashii Clinic Hiroo Shirokane

Last Updated: April 2, 2026

What You'll Learn in This Article

• What dry skin (xerosis / asteatotic dermatitis) actually is — and when it becomes a medical condition

• How the skin barrier breaks down and why this causes itch and inflammation

• How to choose and apply moisturizers correctly for maximum benefit

• When OTC products are insufficient and prescription treatment is needed

• How Tokyo's dry winters, indoor heating, and bathing habits affect skin health

Dry skin — medically termed xerosis cutis or, when inflamed, asteatotic dermatitis (also known as eczema craquelé) — is one of the most common dermatological complaints worldwide. While it is often dismissed as a cosmetic inconvenience, untreated dry skin progresses through a well-defined inflammatory cascade that leads to itch, cracking, secondary infection, and significant impairment of daily life. In Tokyo's dry winter climate, exacerbated by indoor heating and high-temperature bathing habits, dry skin is a year-round concern for a large proportion of residents — including the expat community in Hiroo, Shirokane, and Minami-Azabu.

Table of Contents

1. What Is Dry Skin? Xerosis and Asteatotic Dermatitis Defined

Xerosis cutis refers to abnormally dry skin resulting from reduced skin surface lipids, natural moisturizing factor (NMF) depletion, and impaired water-holding capacity of the stratum corneum. It is not a single disease but a spectrum:

• Xerosis / dry skin: visible scaling and dryness without active inflammation

• Asteatotic dermatitis (eczema craquelé): dry skin with superimposed inflammation — itch, erythema, fissuring

• Nummular eczema: a related pattern of coin-shaped eczematous plaques on a dry skin background

In Japan, asteatotic dermatitis is classified as 皮脂欠乏性湿疹 (sebum-deficient eczema) and is the most common dermatological diagnosis in older adults. It is distinct from atopic dermatitis, though the two may coexist.

Common Misconceptions

• "Dry skin is just cosmetic — it doesn't need treatment." Untreated xerosis progresses to asteatotic dermatitis and can lead to secondary bacterial infection — particularly dangerous in older adults.

• "Moisturizers just add water to the skin." The primary function of emollients is to prevent water loss (TEWL reduction), not to add water. Formulation choice and application technique matter greatly.

• "Only older people get dry skin." While aging is the primary risk factor, dry skin occurs at all ages — particularly in individuals using harsh cleansers, living in low-humidity environments, or taking certain medications.

2. Symptoms — From Subtle Dryness to Cracked, Inflamed Skin

Mild (xerosis)

• Tightness and roughness after bathing or in dry environments

• Fine white scaling (flaking) on shins, arms, and back

• Dull, matte skin texture

• Occasional mild itch

Moderate (early asteatotic dermatitis)

• Intense itch — often worse at night, after bathing, or in heated rooms

• Cracking (fissuring) of the skin surface — particularly on the anterior shins and forearms

• Erythema (redness) beginning to appear

• Excoriations (scratch marks) on the body

Severe (established asteatotic dermatitis)

• Widespread eczema — trunk, limbs, back

• Lichenification (skin thickening from chronic scratching)

• Bleeding from deep fissures

• Secondary infection (Staphylococcus aureus impetigo, cellulitis)

• Sleep disruption, functional impairment

"I realized I'd been waking up every night scratching my legs and back. I'd been applying moisturizer but apparently not enough, or not the right kind. By the time I came to the clinic, I had broken skin and scabbing on my shins." This pattern — progressive itch despite basic moisturizing, with visible skin damage — is typical of asteatotic dermatitis requiring prescription treatment.

3. Causes: Aging, Environment, Habits, and Underlying Disease

Aging Sebaceous gland output and sweat gland function decline with age. NMF components (urocanic acid, pyrrolidone carboxylic acid) and epidermal ceramide content decrease progressively. After 60, transepidermal water loss (TEWL) rises substantially, explaining the dramatic increase in dry skin prevalence in older adults.

Environmental factors — Tokyo-specific

• Winter low humidity: outdoor absolute humidity falls sharply from November through March

• Indoor heating (air conditioning / kerosene heaters): indoor humidity commonly drops below 30–40% without humidification

• High-temperature bathing: Japanese hot spring and bath culture — soaking at 42°C+ strips skin lipids effectively

Habits

• Frequent, hot, prolonged baths or showers

• Harsh or highly foaming cleansers (high pH disrupts acid mantle)

• Vigorous towel drying (mechanical damage to stratum corneum)

• Insufficient or absent moisturizer use

• Wool or synthetic fabrics in direct skin contact

Underlying conditions

• Hypothyroidism: systemic metabolic slowdown reduces sebum and sweat production

• Diabetes: impaired skin metabolism, neuropathic itch

• Chronic kidney disease and dialysis: uremic itch, fluid shifts after dialysis

• Malignancy: paraneoplastic xerosis

• Medications: diuretics, statins, retinoids, targeted cancer therapies

4. The Mechanism: Skin Barrier Dysfunction and TEWL

The stratum corneum functions as a "brick-and-mortar" structure:

• Bricks: corneocytes (protein-rich dead skin cells)

• Mortar: lamellar lipids — primarily ceramides, free fatty acids, and cholesterol

Normal barrier: tightly packed lipids seal the stratum corneum, keeping TEWL low and external allergens/irritants out.

Dry skin cascade:

1. Lipid depletion (aging, over-cleansing, low humidity) → disrupted lamellar structure → increased TEWL

2. NMF depletion → reduced intracellular water binding → stratum corneum becomes rigid and brittle

3. Microcracking → allergens, irritants, and bacteria penetrate → innate immune activation

4. Cytokine release (IL-1α, TNF-α) → inflammation, itch signaling via TRPV1 and histamine pathways

5. Scratching → further barrier disruption → return to step 1 (itch-scratch cycle)

Why this explains the treatment logic:

• Emollients target steps 1–2: restore lipid barrier, reduce TEWL

• Topical corticosteroids target step 4: suppress inflammatory cytokines

• Antihistamines reduce itch signaling: break the scratch cycle

• Environmental humidification reduces the ambient humidity gradient driving TEWL

5. How to Tell Dry Skin Apart from Similar Conditions

Critical warning: Applying topical corticosteroids to tinea (fungal infection) suppresses the immune response and allows fungal proliferation — producing tinea incognito (occult, treatment-resistant ringworm). Self-treatment of presumed "dry skin" with potent steroids without professional diagnosis is a common and avoidable cause of this complication.

6. Diagnosis: Examination, History, and Testing

Physical Examination Assessment of scale morphology, fissure depth, erythema distribution, signs of secondary infection, lichenification. Dermoscopy helps differentiate dry skin patterns from psoriasis (dotted vessels) or tinea.

Medical History

• Season and environment: does it worsen in winter or with air conditioning?

• Bathing habits: water temperature, bath duration, cleanser type

• Moisturizer use: type, quantity, timing relative to bathing

• Medical history: thyroid status, diabetes, kidney function, cancer treatment

• Current medications

• Atopic or allergic history

Laboratory Tests (as indicated)

• KOH microscopy: to exclude tinea

• Skin biopsy: if psoriasis or vasculitis is suspected

• Blood tests: TSH/FT4 (thyroid), HbA1c (diabetes), eGFR (renal function), IgE (atopy screen)

7. Treatment — Emollients, Topical Steroids, and Skincare Guidance

Emollients (the cornerstone of treatment) — Insurance covered

Prescription emollients available at our clinic:

• Heparinoid (Hirudoid® cream/lotion/soft ointment): most commonly prescribed; combined emollient, anti-inflammatory, and blood flow-promoting effects

• Urea 10–20% cream (Urepearl®): keratolytic action ideal for thick, fissured skin; avoid on broken skin

• White petrolatum (Propeto®): simple, safe, highly occlusive; appropriate for infants and sensitive skin

Topical Corticosteroids — Insurance covered Required when xerosis has progressed to asteatotic dermatitis (active inflammation). Potency selected by body site and severity. Applied to inflamed areas; emollient applied over the entire surface simultaneously.

Antihistamines — Insurance covered For patients with significant nocturnal itch impairing sleep. First-generation sedating antihistamines at night; second-generation daytime.

Tacrolimus (Protopic®) — Insurance covered Non-steroidal option for sensitive facial or neck skin where prolonged steroid use is not appropriate.

Skincare guidance: We provide detailed practical instruction on emollient selection, application technique, bathing modification, and environmental adjustment — in English if preferred.

8. How Long Does Recovery Take?

• Mild xerosis: With consistent daily emollient use, skin texture and itch typically improve within 2–4 weeks

• Asteatotic dermatitis: Emollient + topical corticosteroid combination; active inflammation subsides in 1–3 weeks in most cases (individual variation applies)

• Chronic or lichenified cases: May require several months of sustained treatment

The critical principle: moisturizing must continue after symptoms resolve. Dry skin is a chronic tendency — stopping emollients when the skin feels better leads to predictable relapse, typically within weeks in winter conditions.

9. Everyday Habits That Help

Bathing (the most impactful changeable factor)

• Lukewarm water (38–40°C / 100–104°F) — hot baths are the single most common modifiable cause of asteatotic dermatitis in otherwise healthy adults

• Duration under 10–15 minutes

• Gentle, pH-balanced, fragrance-free cleanser — lather with hands, not a washcloth

• Pat dry with a soft towel — never rub

• Apply emollient within 10 minutes of bathing — before the skin has fully dried

Moisturizer application

• Apply generously: a common mistake is using insufficient quantity

• Cover all dry-prone areas, not just symptomatic zones — preventive application is effective

• Apply thicker ointments first, then cream/lotion over the top if desired

Home environment

• Target indoor humidity 50–60%: use a humidifier in the bedroom and main living space — particularly important in Tokyo apartments with central heating during winter

• Avoid direct airflow from air conditioning or heaters onto exposed skin

• Cotton bedding and sleepwear — wool and synthetics increase friction and thermal load

Diet and hydration

• Maintain adequate fluid intake (approx. 1.5–2L/day)

• Ensure adequate dietary fat, vitamins A and E for barrier lipid synthesis

10. Risks of Leaving Dry Skin Unmanaged

Asteatotic dermatitis (inflamed dry skin) Without treatment, xerosis predictably progresses to asteatotic dermatitis — requiring prescription treatment rather than OTC emollients. The longer inflammation persists, the more entrenched the itch-scratch cycle becomes.

Lichenification Chronic scratching causes epidermal thickening that responds poorly to topical treatment and takes months to resolve.

Secondary bacterial infection Fissured dry skin provides a portal of entry for Staphylococcus aureus. Impetigo and cellulitis are significant risks, particularly in older adults with impaired immune function.

Tinea incognito Misidentified tinea treated with topical steroids produces occult, spreading fungal infection that is difficult to treat.

Missed systemic disease In older adults, generalized xerosis with intractable itch can be the presenting symptom of hypothyroidism, chronic kidney disease, or malignancy. A dermatology consultation with internal medicine perspective — as offered at our clinic — enables appropriate systemic screening.

11. Who Is at Higher Risk?

• Adults over 60: Dramatic reduction in sebaceous output; xerosis is near-universal in this group without adequate skincare

• Dialysis patients and chronic kidney disease: Uremic itch and post-dialysis fluid shifts cause severe, often intractable pruritus

• Hypothyroid patients: Systemic metabolic reduction affects skin hydration and sebum production

• Cancer patients (chemotherapy, targeted therapy, radiation): Skin toxicity from treatment causes xerosis and dermatitis requiring active management

• Infants and young children: Thin, easily disrupted barrier; early moisturization may reduce atopic dermatitis risk

• Expats in Tokyo: High-temperature Japanese bath culture and winter indoor heating are unfamiliar environmental conditions that can trigger or worsen dry skin rapidly; English-language skincare guidance is available at our clinic

12. When to See a Doctor — Checklist

• ☑ OTC moisturizers have not improved symptoms after 2 weeks of consistent use

• ☑ Itch is waking you at night or causing significant distress during the day

• ☑ Deep fissures (cracks) with bleeding have developed

• ☑ Redness or eczema has appeared on top of the dry skin

• ☑ Dry skin is widespread across the trunk and limbs

• ☑ You are over 60 and have developed new, generalized itch

• ☑ Annular (ring-shaped) rash or thick, silvery scale is present — may not be dry skin

• ☑ You have diabetes, thyroid disease, or kidney disease and dry skin is worsening

13. Prevention: Skincare, Environment, and Lifestyle

Year-round moisturizing habit The most effective prevention is establishing a daily moisturizing routine before symptoms appear — ideally beginning in October as Tokyo's humidity begins its seasonal decline.

Emollient selection guidance

• Mild dryness / young adults: Heparinoid lotion or ceramide-containing cream

• Moderate dryness / shins and forearms: Heparinoid cream or 10% urea cream

• Severe dryness / fissures: White petrolatum or heparinoid soft ointment

• Face: Oil-free, fragrance-free non-comedogenic formulations

Environmental optimization

• Humidifier in bedroom: target 50–60% RH year-round

• Avoid prolonged time in extremely dry air (aircraft cabin, heavily air-conditioned offices)

• When walking in the dry winter air near Arisugawa-no-miya Memorial Park or along the Hiroo Promenade, apply a barrier cream to exposed skin before going out and re-moisturize upon returning indoors

Bathing culture modification For those accustomed to hot baths: reducing water temperature to 38–40°C and limiting soak time to under 15 minutes, followed by immediate moisturization, is the single highest-impact behavioral change for dry skin management.

14. Dermatology Care at Yasashii Clinic Hiroo Shirokane

English-Friendly, Practical Skincare Guidance

At Yasashii Clinic, we provide dermatology consultations in English for residents of Hiroo, Minami-Azabu, Shirokane, and Ebisu. Dry skin management involves specific, practical skincare advice — emollient selection, application technique, bathing temperature guidance, humidifier use — and we communicate all of this clearly in English.

We accept Japanese national health insurance and self-pay. For those on international insurance plans, we can provide documentation for reimbursement.

Dr. Suzuki's Integrated Approach

Because dry skin in older adults can reflect systemic disease, and because conditions like psoriasis, tinea, and atopic dermatitis require different treatment from xerosis, Dr. Suzuki's background in internal medicine and primary care means our consultations go beyond skin-surface assessment. We check relevant systemic factors, order appropriate labs when indicated, and ensure that the treatment we prescribe is actually targeting the right condition.

"Dry skin is often dismissed, but for patients with severe itch and broken sleep, it is genuinely disabling. There are effective solutions — and they start with the right diagnosis."

For patients requiring specialist referral (e.g., psoriasis requiring biologics, complex systemic workup), we coordinate with Tokyo Metropolitan Hiroo Hospital, Japanese Red Cross Medical Center, Kitasato University Kitasato Institute Hospital, and the University of Tokyo's Institute of Medical Science Hospital.

Access & Hours

• 5 min walk from Hiroo Station (Tokyo Metro Hibiya Line, Exit 2)

• 10 min walk from Ebisu Station (JR / Tokyo Metro)

• 13 min from Shirokanedai and Shirokane-Takanawa Stations

• Parking available

Opening Hours: Monday: 16:00–20:00 | Wednesday & Thursday: 10:00–14:00 / 16:00–20:00 Saturday & Sunday: 10:00–18:00 | Public Holidays: 10:00–14:00 Closed: Tuesday, Friday Please check the official website or call for the latest schedule.

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15. Summary

• Dry skin (xerosis/asteatotic dermatitis) results from skin barrier dysfunction — reduced ceramides, NMF, and sebum — leading to increased water loss, itch, and inflammation

• Daily emollient use is the cornerstone of prevention and treatment — the goal is maintaining the barrier long-term, not just treating flares

• When xerosis has progressed to asteatotic dermatitis (inflammation, itch disrupting sleep, fissures), prescription emollients and topical corticosteroids are needed

• Generalized itch in older adults or treatment-resistant cases should be evaluated for underlying systemic disease

• Correct diagnosis matters: tinea and psoriasis both mimic dry skin and require entirely different treatments

English FAQ

Q1. What causes dry skin? The primary causes are: age-related decline in sebaceous function and ceramide production; environmental low humidity (Tokyo winters, indoor heating); bathing in hot water with harsh cleansers; and underlying conditions such as hypothyroidism, diabetes, or chronic kidney disease.

Q2. Is dry skin contagious? No. Xerosis is not infectious. However, if dry, fissured skin becomes secondarily infected with bacteria, the infection itself (e.g., impetigo) can be contagious.

Q3. How long does treatment take? Mild xerosis typically improves within 2–4 weeks of consistent emollient use. Asteatotic dermatitis (with active inflammation) usually responds to combination emollient + topical corticosteroid within 1–3 weeks. Maintenance moisturizing must continue indefinitely to prevent relapse.

Q4. Can OTC moisturizers clear my dry skin? For mild xerosis, yes — with the right product, correct quantity, and good timing (within 10 minutes of bathing). For asteatotic dermatitis (inflammation, fissures, sleep-disrupting itch), prescription emollients and topical corticosteroids are more effective. If OTC moisturizers have not helped after 2 weeks, please see a dermatologist.

Q5. What is the difference between dry skin and eczema? Xerosis (dry skin without inflammation) and atopic dermatitis are distinct but related. Asteatotic dermatitis is dry skin that has progressed to include inflammation — it is sometimes called "dry skin eczema" and sits between the two. Atopic dermatitis involves a genetic predisposition (filaggrin mutation, atopic family history) and has a characteristic distribution in the flexures. A dermatologist can distinguish these on examination.

Q6. Does diet affect dry skin? Adequate hydration, dietary fat intake, and vitamins A and E support barrier function. There is no single "dry skin diet," but dehydration and fat-deficient diets worsen skin lipid availability. Very low-calorie or ketogenic diets can sometimes trigger or worsen xerosis.

Q7. Are prescription moisturizers better than OTC products? Prescription heparinoid preparations (Hirudoid® cream/lotion) have combined emollient, anti-inflammatory, and circulatory properties not found in most OTC products. They are covered by Japanese health insurance, making them cost-effective for regular use. For many patients with chronic dry skin, they provide meaningfully better outcomes than OTC alternatives.

Q8. Do you see foreign patients? Is English available? Yes — we regularly see expats and foreign residents from Hiroo, Minami-Azabu, Shirokane, and Ebisu for skin conditions including dry skin. English is available at our clinic.

Q9. Is dry skin treatment covered by Japanese health insurance? Yes. Prescription emollients (heparinoid, urea cream), topical corticosteroids, and antihistamines are all covered by Japanese national health insurance. Out-of-pocket costs for a standard consultation plus emollient prescription are typically modest (exact amount varies by plan and prescription scope).

Q10. Can I have an online consultation for dry skin? Follow-up consultations and moisturizer prescription renewals are well-suited to online consultation. For first visits — particularly if the diagnosis is uncertain (possible tinea, psoriasis, or systemic condition) — an in-person visit is recommended so we can examine the skin directly.

Author:
Name: Yasumasa Ohno
Role: Business Development & Content Manager, Yasashii Clinic Hiroo Shirokane

Medical Reviewer:
Name: Takafumi Suzuki, MD

Credentials: Specialist in Anesthesiology (Japan Board of Anesthesiology)

Affiliations:
- Japanese Society of Anesthesiologists (JSA)
- Japanese Society of Internal Medicine (JSIM)
- Japanese Society of Intensive Care Medicine (JSICM)
- Japanese Association for Cardiovascular Anesthesia (JACA)
Clinical Background: Critical care medicine, perioperative management, pain medicine; primary care in internal medicine, dermatology, allergology, and sleep medicine (OSA)

Operating Organization:
Name (Japanese): やさしいクリニック 広尾 白金
Name (English): Yasashii Clinic Hiroo Shirokane
Address: O-KA Building 3F, 2-31-3 Ebisu, Shibuya-ku, Tokyo 150-0013, Japan
Tel: +81-3-6456-4990
URL: https://yasashii-clinic.jp
Booking: https://line.me/R/ti/p/@744yxkjg (LINE, 24/7)
Specialties: Internal Medicine / Dermatology / Allergology / Pain Clinic

Opening Hours:
Monday : 16:00–20:00
Tuesday : Closed
Wednesday : 10:00–14:00 / 16:00–20:00 (2nd & 4th Wed: morning only)
Thursday : 10:00–14:00 / 16:00–20:00
Friday : Closed
Saturday : 10:00–18:00
Sunday : 10:00–18:00
Public Holidays: 10:00–14:00

* Hours subject to change. Please check the official website for the latest schedule.

Access:
5 min walk from Hiroo Station (Tokyo Metro Hibiya Line, Exit 2)
10 min walk from Ebisu Station (JR / Tokyo Metro)
13 min walk from Shirokane-Takanawa / Shirokanedai Station
Languages: Japanese (primary), English available
Online Consultation: Available
Payment: Cash / Credit cards accepted
Last Updated: 2026-04-02
Medical Disclaimer:
This article is for general informational purposes only and does not constitute medical advice, diagnosis, or treatment. The information provided reflects current medical knowledge at the time of writing. Individual symptoms and conditions vary; please consult a qualified physician for personal medical advice. If you are experiencing an emergency, contact emergency services immediately. This content has been medically reviewed by a licensed physician.